2021/10/27 更新

写真a

オグラ カズオ
小椋 一夫
OGURA Kazuo
所属
教育研究院 自然科学系 情報電子工学系列 教授
自然科学研究科 電気情報工学専攻 教授
工学部 工学科 教授
職名
教授
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外部リンク

学位

  • 理学博士 ( 1989年5月   京都大学 )

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 電子デバイス、電子機器

  • エネルギー / プラズマ科学

  • エネルギー / 核融合学

経歴(researchmap)

  • 新潟大学   工学部 工学科   教授

    2017年4月 - 現在

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  • 新潟大学   自然科学研究科 電気情報工学専攻   教授

    2010年4月 - 現在

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  • 新潟大学   自然科学研究科 電気情報工学専攻   教授

    2010年4月 - 現在

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  • 新潟大学   工学部 電気電子工学科   教授

    1999年4月 - 2017年3月

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  • 新潟大学   工学部   助教授

    1993年4月 - 1999年3月

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  • 新潟大学   自然科学研究科   助手

    1989年3月 - 1993年3月

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経歴

  • 新潟大学   工学部 工学科   教授

    2017年4月 - 現在

  • 新潟大学   自然科学研究科 電気情報工学専攻   教授

    2010年4月 - 現在

  • 新潟大学   自然科学研究科 電気情報工学専攻   教授

    2010年4月 - 現在

  • 新潟大学   電気電子工学科   教授

    1999年4月 - 2017年3月

  • 新潟大学   工学部   助教授

    1993年4月 - 1999年3月

  • 新潟大学   自然科学研究科   助手

    1989年3月 - 1993年3月

▶ 全件表示

所属学協会

 

論文

  • Design and Fabrication of 200-GHz Oversized Surface-Wave Oscillator

    Yuta Annaka, Kazuo Ogura, Keiichiro Rachi, Yukihisa Hoshi, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    IEEE Transactions on Plasma Science   49 ( 1 )   33 - 39   2021年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Institute of Electrical and Electronics Engineers (IEEE)  

    DOI: 10.1109/tps.2020.2998119

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  • Spoof-Plasmon Instability in Terahertz Region Excited by Magnetized Electron Beam

    Kazuo Ogura, Yuta Annaka, Yukihisa Hoshi, Toru Takahashi

    IEEE Transactions on Plasma Science   49 ( 1 )   40 - 47   2021年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Institute of Electrical and Electronics Engineers (IEEE)  

    DOI: 10.1109/tps.2020.3011469

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  • Experimental study of surface-wave oscillator with different electron beam forms 査読

    Japanese Journal of Applied Physics   59 ( SH )   2020年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Enhancement-limit of Smith-Purcell radiation with self-bunched keV-order electron beam 査読 国際誌

    Yuta Annaka, Kazuo Ogura, Yuki Sato, Makoto Nakasone, Keiichiro Rachi, Toru Takahashi, Yukihisa Hoshi

    Physics of Plasmas   27 ( 023102 )   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Study of Spoof Plasmon Formed on Periodically Corrugated Metal Surface Based on Cavity Resonance Method 査読

    Kazuo OGURA, Kei SEKINE, Yuta ANNAKA, Min Thu SAN

    Plasma and Fusion Research   14 ( 2406008 )   2019年1月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.1585/pfr.14.2406008

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  • Non-axisymmetric Radiation from Surface-Wave Oscillator Driven by Weakly Relativistic Electron Beam 査読

    Yuta ANNAKA, Kazuo OGURA, Kosuke OZAWA, Makoto NAKASONE, Yuki SATO

    Plasma and Fusion Research   14 ( 2406015 )   2019年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.14.2406015

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  • Experimental Study on Backward Wave Oscillators Using Dielectric Discharge Cold Cathodes 査読

    M. Sakagami, A. Sugawara, T. Otsuki, Y. Annaka, Min Thu San, K. Yambe, K. Ogura, W. Kim

    Plasma and Fusion Research   13 ( 2 )   3406107_1 - 4   2018年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.13.3406107

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  • Enhancement of Smith-Purcell radiation with temporal harmonics of surface wave on cylindrical corrugated waveguide 査読

    Y. Annaka, K. Ogura, K. Ozawa, K. Sekine, Min Thu San

    Physics of Plasmas   25 ( 6 )   063115-1 - 063115-6   2018年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Institute of Physics Inc.  

    We experimentally studied an intense Smith-Purcell (SP) radiation based on a cylindrical corrugated waveguide driven by a weakly relativistic electron beam. The corrugated waveguide has a rectangular periodic structure, and an annular electron beam with energy less than 100 keV and current of the order of 100 A is injected. We observe both intense surface-wave radiation at 25 GHz and intense SP radiations up to 150 GHz. The observed SP radiations are enhanced by the sixth and fourth temporal harmonics of the surface wave. The characteristics of the enhanced SP radiation depend on the periodic number of the structure. In the experiment with the use of the 60-period structure, the observed power of the SP radiation at the fourth harmonic is higher than that of the radiation at the sixth harmonic. In the case of the 30 period-structure, the power level of the radiation at the sixth harmonic is comparable to that at the fourth harmonic.

    DOI: 10.1063/1.5035139

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  • Study on Operation of Oversized Backward Wave Oscillator for Broadband Terahertz Radiation 査読

    Min Thu San, Kazuo Ogura, Kazuki Kubota, Yuta Annaka, Kiyoyuki Yambe, Akira Sugawara

    IEEE TRANSACTIONS ON PLASMA SCIENCE   46 ( 3 )   530 - 538   2018年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE  

    DOI: 10.1109/TPS.2018.2796559

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  • Study on Operation of a Surface Wave Oscillator around the π-point Region 査読

    Min Thu San, Kazuo Ogura, Member, IEEE, Kiyoyuki Yambe, Yuta Annaka, Junpei Fujita

    IEEE Transactions on Plasma Science   45 ( 1 )   30 - 38   2017年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1109/TPS.2016.2633550

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  • 弱い相対論的電子ビームを用いた大口径W-band表面波発振器による大強度マイクロ波の発振特性 査読

    安中裕大, 山家清之, 小椋一夫

    電気学会論文誌A   137 ( 3 )   165 - 170   2017年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:電気学会  

    DOI: 10.1541/ieejfms.137.165

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  • Beam Interactions With Surface Waves and Higher Order Modes in Oversized G-band Slow-Wave Structure 査読

    Kazuo Ogura, Akihiro Shirai, Masahiko Ogata, Shaoyan Gong, Kiyoyuki Yambe

    IEEE TRANSACTIONS ON PLASMA SCIENCE   44 ( 2 )   201 - 210   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    Beam interactions with surface waves and higher order modes in oversized G-band slow-wave structures (SWSs) are studied in a coaxial SWS. The coaxial SWS reduces the number of higher order mode and eases the mode competition problem. The SWS is excited by an annular electron beam. The slow cyclotron (SC) interaction as well as the Cherenkov interaction occurs due to 3-D beam perturbations of the electron beam. Growth rates for the surface waves are larger than those for the higher order modes and increase with increasing beam current. The SC interaction merges with the Cherenkov interaction for a sufficiently high beam current and a relatively low magnetic field. And the merged growth rate also increases with the beam current.

    DOI: 10.1109/TPS.2016.2514380

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  • Dependence of Plasma Plume Formation on Applied Voltage Waveform in Atmospheric-Pressure Plasma 査読

    Kiyoyuki Yambe, Kohmei Konda, Kazuo Ogura, Hajime Sakakita

    IEEE TRANSACTIONS ON PLASMA SCIENCE   44 ( 1 )   107 - 112   2016年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    We have studied an atmospheric-pressure plasma generated using a quartz tube, helium gas, and a copper foil electrode by the application of a radio-frequency high voltage. The atmospheric-pressure plasma, which is generated in the form of a bullet, is released as a plume into the atmosphere. To study the properties of plasma plume formation, we examine the relationships among the plasma plume length and charge and the applied voltage waveform. The dependences of the waveform on the plasma plume length and charge are not clear. However, the plasma plume length increases with increasing plasma plume charge in laminar flow. Consequently, we find that the plasma plume length depends on the plasma plume charge becoming an energy source so that electric charge travels the plasma.

    DOI: 10.1109/TPS.2015.2506784

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  • Experimental study on W-band (75 - 110 GHz) oversized surface wave oscillator driven byweakly relativistic electron beams 査読

    Min Thu San, Kazuo Ogura, Kiyoyuki Yambe, Yuta Annaka, Shaoyan Gong, Jun Kawamura, Takuro Miura, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    Plasma and Fusion Research   11 ( 1 )   2406085   2016年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Japan Society of Plasma Science and Nuclear Fusion Research  

    A W-band (75 - 110 GHz) oversized surface wave oscillator driven by weakly relativistic electron beams with energy in the range of 10 - 80 keV is studied. Rectangular corrugations are used as slow-wave structures (SWS) having surface waves with an upper cutoff frequency of approximately 100 GHz (W-band). Uniformly distributed annular electron beams are generated by a disk-type cold cathode and then are injected into theW-band oscillator. A longer SWS length causes the oscillator to function in both backward wave oscillator (BWO) and travelling wave tube (TWT) operations, and no meaningful oscillation occurs at the π-point or the Bragg condition. When the SWS length is short enough, oscillation occurs in all regions: BWO, π-point and TWT. The operations of the oscillator are strongly affected by the structure length. The maximum radiation power is estimated to be approximately 20kW with the figure of merit of about 2 � 102MW.GHz2.

    DOI: 10.1585/pfr.11.2406085

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  • Measurement Method of Plasma Current and Density in Atmospheric Pressure Plasma Jet 査読

    Kiyoyuki Yambe, Hiroki Saito, Kazuo Ogura

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   10 ( 6 )   614 - 618   2015年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    We present a measurement method of the plasma current and density in an atmospheric-pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying a high RF voltage. The plasma in the form of a bullet is released as a plume or jet into the atmosphere. To study the characteristics of the atmospheric-pressure plasma, the plasma current is measured using a current probe, and the drift velocity of plasma plume is measured using a photodetector. The current of the plasma plume is estimated by subtracting the ground line current from the power line current in the circuit. The density of plasma plume n is estimated from the plasma plume current I and the drift velocity v as I = envS, where S is the cross section of plasma plume. The density of the released plasma into the atmosphere is estimated as similar to 10(18) m(-3) by the method. (C) 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

    DOI: 10.1002/tee.22127

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  • Oscillation-Starting Conditions for Oversized G-Band (140-220 GHz) Backward Wave Oscillator Driven by Weakly Relativistic Electron Beam 査読

    Shaoyan Gong, Kazuo Ogura, Shintaro Nomizu, Akihiro Shirai, Kosuke Yamazaki, Kiyoyuki Yambe, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    IEEE TRANSACTIONS ON PLASMA SCIENCE   43 ( 10 )   3530 - 3536   2015年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    An oversized G-band backward wave oscillator (BWO) driven by a weakly relativistic electron beam less than 100 kV is studied. Rectangular corrugations are used as the slow-wave structure (SWS), which have surface waves with upper cutoff frequencies of above 150 GHz [G-band (140-220 GHz)]. In this paper, we examine the starting conditions for intense G-band BWO operation by varying the beam parameters and SWS lengths. It is shown that a starting energy exists for the G-band BWO and that the starting energy is more critical than the starting current in the oversized BWO. Above the starting energy, very intense output powers on the order of 10 kW are obtained. The oscillation-starting condition for such intense operation may play an important role in high-intensity terahertz wave sources.

    DOI: 10.1109/TPS.2015.2424993

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  • Experimental study of intense radiation in terahertz region based on cylindrical surface wave resonator 査読

    Shaoyan Gong, Kazuo Ogura, Kiyoyuki Yambe, Shintaro Nomizu, Akihiro Shirai, Kosuke Yamazaki, Jun Kawamura, Takuro Miura, Sho Takanashi, Min Thu San

    JOURNAL OF APPLIED PHYSICS   118 ( 12 )   2015年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Periodical corrugations structured on a cylindrical conductor have cylindrical surface waves (CSWs), which are reflected at the corrugation ends and form a CSW-resonator. In this paper, intense radiations in terahertz region based on the CSW-resonator are reported. The CSW-resonators with upper cut off frequencies in the modern IEEE G-band (110-300 GHz) are excited by a coaxially injected annular beam in a weakly relativistic region less than 100 kV. It is shown that there exists an oscillation starting energy for the CSW-resonator. Above the starting energy, very intense terahertz radiations on the order of kW are obtained. The operation frequencies in the range of 166-173 GHz and 182-200 GHz are obtained using two types of CSW-resonator with the different corrugation amplitude. Electromagnetic properties of the CSW-resonator can be controlled by the artificial structure and may play an important role in high-intensity terahertz generations and applications. (C) 2015 AIP Publishing LLC.

    DOI: 10.1063/1.4931371

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  • Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma 査読

    Kiyoyuki Yambe, Kohmei Konda, Kazuo Ogura

    PHYSICS OF PLASMAS   22 ( 5 )   2015年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air. (C) 2015 AIP Publishing LLC.

    DOI: 10.1063/1.4921657

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  • Enhancement of smith-purcell radiations by selfbunched electron beams in oversized backward wave oscillators

    K. Ogura, K. Yambe, T. Iwasaki, S. Magori, J. Kojima

    ICOPS/BEAMS 2014 - 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams   2015年1月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Institute of Electrical and Electronics Engineers Inc.  

    Smith-Purcell (SP) radiations of weakly relativistic oversized backward wave oscillator (BWO) are examined experimentally. Our oversized BWOs are driven by weakly relativistic electron beams less than 100 keV. New element of this work is an enhancement of SP radiation in the oversized BWO using the bunching section. An annular beam is self-bunched in the K-band bunching section and then is injected into the oversized K-band BWO. SP radiations in the BWO are strongly enhanced in the U-band, which is about twice of the bunching frequency. Moreover, the oversized BWO is developed to G-band. By using the G-band bunching, the SP radiations are enhanced in the H-band. The enhancement of SP-radiation in the oversized BWO by the self-bunched electron beam is attractive to develop THz wave sources.

    DOI: 10.1109/PLASMA.2014.7012770

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  • Relation between plasma plume charge and length in atmospheric pressure plasma 査読

    Kiyoyuki Yambe, Shogo Taka, Kazuo Ogura

    IEEJ Transactions on Electrical and Electronic Engineering   9 ( 1 )   S13 - S16   2014年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:John Wiley and Sons Inc.  

    We present atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying a radio frequency high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the formation of the plasma plume, the dependences of the plasma plume charge and the plasma plume length on the gas flow rate are examined. In a quartz tube with inner diameter 1.5 mm, which has more helium than air in the cross section of the flow channel, the distributions of the length and charge on the gas flow rate show similar tendencies. Consequently, when more helium gas is present than air, the travel length of the plasma plume correlates with the plasma plume charge.

    DOI: 10.1002/tee.22039

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  • Experimental study on Smith-Purcell radiations of weakly relativistic oversized backward wave oscillators 査読

    Takayuki Iwasaki, Kazuo Ogura, Shota Magori, Junpei Kojima, Kiyoyuki Yambe

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   65 ( 8 )   1196 - 1200   2014年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    Smith-Purcell (SP) radiations of weakly relativistic oversized backward wave oscillator (BWO) are examined experimentally. A bunching section composed of a coaxial slow wave structure with inner K-band corrugation is placed upstream from the oversized BWO. An annular beam less than 100 kV is self-bunched in the bunching section and then excites the oversized BWO. SP radiations are examined by using 25.5- and 45.0-GHz oversized BWOs. The beam is too far away from the walls of the oversized BWO for SP radiation to occur without the self-bunching. When the corrugation parameters of the bunching section are the same as those of the oversized BWO, enhanced SP radiations in the frequency region above the surface wave are observed even when the beam propagates outside the interaction region of the surface wave.

    DOI: 10.3938/jkps.65.1196

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  • Electromagnetic Properties of a Trapezoidally Corrugated Slow Wave Structure for Backward Wave Oscillators 査読

    Md Ruhul Amin, Kazuo Ogura, Junpei Kojima, Rakibul Hasan Sagor

    IEEE TRANSACTIONS ON PLASMA SCIENCE   42 ( 6 )   1495 - 1501   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    In this paper, the electromagnetic properties of a beam free trapezoidally corrugated slow wave structure (TCSWS) are numerically and experimentally investigated. The dimensions of the TCSWS are selected so that it can be deployed in X-band backward wave oscillators (BWOs). The theoretical dispersion characteristics for the axisymmetric TM01-TM03 modes are obtained by solving the dispersion equation numerically. In order to verify the numerical calculation, a cold test is conducted using a 6-period TCSWS cavity and a vector network analyzer (VNA). The cavity is excited by a small needle-type antenna and frequency of the VNA is swept over the passbands. The dispersion characteristics are obtained from frequency values of the discrete resonant peaks of reflection measurement of each TM mode. Experimental results show an excellent agreement with numerical ones. The numerical and cold test results reveal that TCSWS can be used as an alternative to sinusoidally corrugated slow wave structure in BWO experiments with an advantage of ease of fabrication.

    DOI: 10.1109/TPS.2014.2308434

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  • Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma 査読

    Kiyoyuki Yambe, Shogo Taka, Kazuo Ogura

    PHYSICS OF PLASMAS   21 ( 4 )   043511-1 - 043511-1   2014年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n(plu), which is estimated from the current and the drift velocity, and the gas flow velocity v(gas) is examined. It is found that the dependence of the density on the gas flow velocity has relations of n(plu) proportional to log(v(gas)). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity. (C) 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4873384

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  • Influence of Gas Flow on Plasma Length in Atmospheric Pressure Plasma Jet 査読

    Kiyoyuki Yambe, Tsubasa Furuichi, Kazuo Ogura

    JPS Conference Proceedings   1   015084-1 - 015084-1   2014年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.7566/JPSCP.1.015084

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  • Beam interactions with surface waves and higher-order modes in oversized backward wave oscillators 査読

    Kazuo Ogura, Akihiko Kojima, Fumiaki Kawabe, Kiyoyuki Yambe, Md. Ruhul Amin

    Journal of the Korean Physical Society   65 ( 8 )   1209 - 1214   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Korean Physical Society  

    Beam interactions with surface waves and higher-order modes in an oversized backward wave oscillator (BWO) are studied. In addition to the well-known Cherenkov interaction, the slow cyclotron interaction occurs due to transverse perturbations of the electron beam. The Cherenkov interaction dominates the slow cyclotron interaction. Growth rates of both the interactions for the higher order modes are small compared with those for the surface-wave modes in an oversized BWO. The coaxial slow-wave structure exhibits a reduced number of higher-order modes, which consequently reduces the mode competition problem and improves beam interactions with higher-order modes. For higher values of beam currents, the slow cyclotron wave grows at a faster rate than the Cherenkov waves.

    DOI: 10.3938/jkps.65.1209

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  • Surface waves in oversized G-band slow-wave structures with rectangular corrugations 査読

    Kazuo Ogura, Akihiko Kojima, Fumiaki Kawabe, Kiyoyuki Yambe, Md. Ruhul Amin

    Plasma and Fusion Research   9 ( 2 )   340622-1 - 340622-4   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Japan Society of Plasma Science and Nuclear Fusion Research  

    Surface waves in oversized G-band slow-wave structure with rectangularly corrugated wall are analyzed numerically. The inner corrugation generates cylindrical surface wave. The outer corrugation also generates transverse magnetic surface wave. The upper cut-offs of surface waves are controlled by corrugation amplitude. In excitation of the surface waves by an annular electron beam, the slow cyclotron interaction as well as the Cherenkov interaction occur due to there-dimensional beam perturbations. The slow cyclotron interaction merges with the Cherenkov interaction at lower magnetic field. The merged growth rate is enhanced by 13%as compared to the isolated Cherenkov growth rate. The surface waves on inner and outer corrugations can have different frequencies and can be excited selectively by adjusting the beam radius of the electron beam. © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.

    DOI: 10.1585/pfr.9.3406022

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  • Experimental study on G-band oversized backward wave oscillator driven by weakly relativistic electron beam 査読

    Shota Magori, Kazuo Ogura, Takayuki Iwasaki, Junpei Kojima, Kiyoyuki Yambe, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    Plasma and Fusion Research   9 ( 2 )   3406032-1 - 3406032-4   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Japan Society of Plasma Science and Nuclear Fusion Research  

    We studied a G-band oversized backward wave oscillator (BWO) driven by a weakly relativistic electron beam of less than 100 kV. Rectangular corrugations are used as slow-wave structures having surface waves with upper cutoff frequencies above 150 GHz (G-band). We examine how dispersion characteristics of surface waves are affected by accuracy in machining the corrugation amplitude, width, and period length. Of these, accuracy in the amplitude has the largest effect. Uniformly distributed annular electron beams are generated by a disk-type cold cathode and injected into the G-band BWO. G-band BWO operations in 137-173 GHz and above 173 GHz are achieved by changing the corrugation amplitude. The radiation patterns are fairly broad, and the estimated radiation power is at kW level. © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.

    DOI: 10.1585/pfr.9.3406032

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  • Normal Modes and Slow-Wave Instabilities in Oversized Coaxial Slow-Wave Structure With Rectangular Corrugations 査読

    Kazuo Ogura, Kiyoyuki Yambe, Kazumasa Yamamoto, Yoshihiro Kobari

    IEEE TRANSACTIONS ON PLASMA SCIENCE   41 ( 10 )   2729 - 2734   2013年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    Normal modes and slow-wave instabilities in an oversized coaxial slow-wave structure (SWS) are numerically analyzed for the case of a weakly relativistic annular beam. The coaxial SWS has outer and inner rectangular corrugations with K-band dimensions. The inner corrugations have a cylindrical surface wave, which is the fundamental mode and exists even if the outer conductor is removed. The outer corrugations generate higher-order waveguide modes. Both transverse and longitudinal beam perturbations are considered in the beam interactions, leading to slow cyclotron instabilities as well as Cherenkov instabilities. The instabilities of axisymmetric and nonaxisymmetric modes have almost the same growth rates. The relative position between the outer and inner corrugations affects the normal modes and may allow wide frequency tunability.

    DOI: 10.1109/TPS.2013.2256932

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  • Temporal Growth Study in Trapezoidally Corrugated Slow-Wave Structure for Backward-Wave Oscillator 査読

    Md. Ruhul Amin, Kazuo Ogura

    IEEE TRANSACTIONS ON PLASMA SCIENCE   41 ( 8 )   2257 - 2263   2013年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    The temporal growth rate (TGR) in a trapezoidally corrugated slow-wave structure for a backward-wave oscillator is theoretically studied. An intense relativistic annular electron is used as the energy source for the device. The annular electron beam is assumed to be infinitesimally thin in the radial extent and guided by an infinitely strong magnetic field. The trapezoidal profile of the structure is approximated by a sinusoidal function using Fourier approximation, and the dispersion relation of the system is derived using the Rayleigh-Fourier method. To study the TGR of the electromagnetic wave inside the system, the dispersion equation is solved for different values of the beam parameters. The dimensions of sinusoidally corrugated comparable trapezoidal structure are determined by comparing their dispersion characteristics. For the TM01 mode, TGR of instability that gives a qualitative measure of the microwave generation is calculated. The peak TGR of the proposed structure is found to be on average 1.5% higher than that of the sinusoidally corrugated slow-wave structure for the same set of beam parameters. Apart from its improved growth rate, the proposed structure has an added advantage of easy fabrication.

    DOI: 10.1109/TPS.2013.2258406

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  • Higher Order Mode Radiations of Weakly Relativistic Oversized Backward Wave Oscillator 査読

    Kazuo Ogura, Kiyoyuki Yambe, Shinji Hasegawa, Takayuki Iwasaki, Kazumasa Yamamoto, Yoshihiro Kobari

    Plasma and Fusion Research   8   2401085-1 - 2401085-5   2013年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.8.2401085

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  • CYLINDRICAL SURFACE WAVES AND SLOW-WAVE INSTABILITIES OF PERIODICALLY CORRUGATED CYLINDER 査読

    Kazuo Ogura, Kazumasa Yamamoto, Yoshihiro Kobari, Kiyoyuki Yambe

    FUSION SCIENCE AND TECHNOLOGY   63 ( 1T )   152 - 155   2013年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOC  

    Cylindrical surface waves (CSWs) and slow-wave instabilities of a rectangularly corrugated cylinder are numerically examined. CSWs are slow waves with upper cutoffs at the pi point. The upper cutoff frequency increases with increasing cylindrical radius R-0. There are two types of higher-order CSWs: one is due to azimuthal standing waves and the other is due to radial standing waves in the corrugation. Both higher-order types of SWSs have lower cutoffs as well as upper cutoffs leading to pass and stop bands. Slow space charge and slow cyclotron modes of an annular beam exist, which excite the Cherenkov and slow cyclotron instabilities of CSWs, respectively. The growth rates of the higher-order CSWs are comparable to those of the fundamental SWSs.

    DOI: 10.13182/FST13-A16893

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  • SMITH-PURCELL RADIATION BASED ON CYLINDRICAL SURFACE WAVES 査読

    Shinji Hasegawa, Kazuo Ogura, Takayuki Iwasaki, Kiyoyuki Yambe

    FUSION SCIENCE AND TECHNOLOGY   63 ( 1T )   259 - 261   2013年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOC  

    Smith-Purcell (SP) radiations based on cylindrical surface wave are examined. Cylindrical surface waves are formed on metal cylinders having a periodically corrugated wall. Corrugation parameters are those used in K-band backward wave oscillators (BWOs). The corrugated metal cylinders are excited by an axially injected coaxial annular beam in a weakly relativistic region less than 100 kV. Cylindrical surface wave excitations due to BWO are observed at about 23 GHz. In addition, SP radiations are observed in the higher frequency regions up to about 90-100 GHz, which is about 4 times higher than the frequency of cylindrical surface wave.

    DOI: 10.13182/FST13-A16921

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  • Experimental study on generation of electron beam utilizing cold cathode in the weakly relativistic energy region 査読

    Kiyoyuki Yambe, Kazuo Ogura, Shinji Hasegawa, Takaki Shinada, Takayuki Iwasaki, Tsubasa Furuichi

    IEEE Transactions on Plasma Science   41 ( 10 )   2781 - 2785   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Electron beam generation in a weakly relativistic region of less than 100 kV is investigated utilizing rectangular and disk cold cathodes made of copper. Electron emission areas are located on the edges of the cathodes. For uniform electron emission, some surface roughness is required on the emission surface, which is obtained by scratching the surface with sandpaper. A uniform sheet beam with a size of about 2×40 mm and an annular beam with a diameter of about 25 mm and a thickness of about 2 mm are demonstrated in the weakly relativistic region. Stable electron beams of sheet and annular shapes are experimentally demonstrated. © 1973-2012 IEEE.

    DOI: 10.1109/TPS.2013.2262505

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  • Cylindrical surface wave on periodically corrugated metal 査読

    Kazuo Ogura, Hiroshi Iiduka, Kiyoyuki Yambe

    Plasma and Fusion Research   7 ( 1 )   2406022-1 - 2406022-4   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We present a numerical and experimental study of the dispersion characteristics of cylindrical surface waves on metallic cylinders with rectangular corrugations. In actual devices, reflections at both ends quantize the electromagnetic modes into resonant axial modes. A cavity method based on axial mode measurements is applied to study the properties of the cylindrical surface waves. The resonances are relatively sharp near the upper cutoff, but at low frequencies far from the cutoff, the resonances broaden to resemble those of a Sommerfeld wave. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.

    DOI: 10.1585/pfr.7.2406022

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  • Numerical Study of Slow-wave Instabilities in an Oversized Coaxial Slow-wave Structure 査読

    Kazuo Ogura, Shingo Abe, Hiroki Kimura, Kazumasa Yamamoto, Kiyoyuki Yambe, Md Ruhul Amin

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   59 ( 6 )   3555 - 3559   2011年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    In this paper, slow-wave instabilities in oversized coaxial slow-wave structures (SWSs) are numerically analyzed. An infinitesimally thin annular beam with transverse perturbations and guided by a finite axial magnetic field is considered as an energy source for creating the instabilities. The coaxial SWSs consist of an outer oversized hollow waveguide and a central conductor and have sinusoidal corrugations. An electromagnetic slow-wave is generated by the inner corrugation and is called the inner surface wave (ISW). The ISW is a cylindrical surface wave and can exist even if the outer conductor is removed. The higher-order modes are produced by the outer waveguide. The annular beam interacts with the ISW and higher-order modes. A slow cyclotron instability occurs due to the transversely modulated beam boundary, in addition to the conventional Cherenkov instability. The slow-wave instabilities can be controlled by using the beam radius and the relative positions of inner and outer corrugations.

    DOI: 10.3938/jkps.59.3555

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  • Experimental Study on Weakly Relativistic Oversized Backward Wave Oscillator with Coaxial Rectangular Corrugations 査読

    Masatoh Takahashi, Kazuo Ogura, Hiroyuki Yoshimura, Hiroshi Iiduka, Akira Sugawara, Kiyoyuki Yambe, Won-Sop Kim

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   59 ( 6 )   3573 - 3577   2011年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KOREAN PHYSICAL SOC  

    Experimental studies of coaxial oversized backward wave oscillators (BWOs) are presented. The beam voltage is weakly relativistic, less than 100 kV. The slow-wave structure (SWS) consists of a rectangularly corrugated oversized hollow waveguide and rectangularly corrugated inner conductor and has a target operating frequency due to Cherenkov interaction is in the K-band. The coaxial SINS can have two surface waves caused by the inner and the outer corrugations. The oversized BWO operations under the influences of two surface waves are examined. The oscillation start voltage is decreased by introducing a rectangularly corrugated inner conductor, The output. power is increased greatly as compared with those without; the corrugated inner conductor. The inner corrugation improves the oversized BWO operation.

    DOI: 10.3938/jkps.59.3573

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  • Experimental study on backward wave oscillation based on cylindrical surfacewave of Smith-Purcell free electron laser 査読

    Kazuo Ogura, Kiyoyuki Yambe, Hiroyuki Yoshimura, Masatoh Takahashi

    Plasma and Fusion Research   6 ( 1 )   2401039_1 - 2401039_4   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Backward wave oscillation based on a cylindrical surface wave of Smith-Purcell free electron laser (SPFEL) is demonstrated. The SP-FEL is composed of a metal cylinder having a periodically corrugated wall and a surrounding hollow straight waveguide. Corrugation parameters are those used in K-band backward wave oscillators (BWOs). The metal cylinder has a surface wave due to the corrugation. The cylindrical surface wave is excited by an axially injected coaxial annular beam. Radiations due to the backward wave oscillation based on the cylindrical surface wave are examined in a weakly relativistic region less than 100 kV. An oscillation starting voltage exists for the backward wave oscillation as in the case of hollow oversized BWO. The frequencies are in K-band and are determined by the cylindrical corrugation. Radiations up to tens of kW are obtained. © 2011 The Japan Society of Plasma Science and Nuclear Fusion Research.

    DOI: 10.1585/pfr.6.2402039

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  • Study on Electron Distribution Function and Spatial Structure of Weakly Relativistic Electrons in Microwave and Mirror Devices

    K., Ogura, K., Bansho, K., Otubo, H., Iizuka, A., Sugawara, T., Imai, M., Yoshikawa, R., Minami

    Annual Report of NIFS, April 2009-March 2010   490   2010年11月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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  • Numerical Analysis of Slow-Wave Instabilities in an Oversized Sinusoidally Corrugated Waveguide Driven by a Finitely Thick Annular Electron Beam 査読

    K. Otubo, K. Ogura, M. Yamakawa, Y. Takashima

    Plasma and Fusion Research   5   S1047_1 - S1047_6   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.5.S1047

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  • Experimental Study of Oversized Backward Wave Oscillator with Coaxial Slow-Wave Structure 査読

    H. Yoshimura, K. Ogura, K. Bansho, H. Iiduka, M. Takahashi, A. Sugawara

    Plasma and Fusion Research   5   S2093_1 - S2093-4   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.5.S2093

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  • Experimental Study of Slow Cyclotron Maser Operation in Weakly Relativistic Region 査読

    K. Bansho, K. Ogura, H. Oe, Y. Kazahari, H. Iizuka, A. Sugawara, T. Shimozuma, S. Kobayashi, K. Okada

    Plasma and Fusion Research   5   S1049-1 - S1049-6   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.5.S1049

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  • Numerical Analysis of Slow-Wave Instabilities in X-band Sinusoidally Corrugated Waveguide with Coaxial Slow-Wave Structure 査読

    S. Abe, K. Ogura, K. Otubo, H. Kimura

    Plasma and Fusion Research   5   S2091_1 - S2091_4   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.5.S2091

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  • Experimental Study on Disk Type Cold Cathode in Weakly Relativistic Energy Region 査読

    H. Oe, K. Ogura, Y. Kazahari, K. Bansho, H. Iizuka, A. Sugawara, W.S.Kim

    Journal of Plasma and Fusion Research Series   8   1477 - 1482   2009年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Analysis of Slow-Wave Instability in Rectangularly Corrugated Cylindrical Waveguide 査読

    Y. Takashima, K. Ogura, M. Yamakawa, K. Otubo, M. R. Amin

    Journal of Plasma and Fusion Research Series   8   1512 - 1517   2009年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Instability of Annular Beam with Finite Thickness in Dielectric-Loaded Cylindrical Waveguide 査読

    S. Tamura, M. Yamakawa, Y. Takashima, K. Ogura

    Plasma and Fusion Research   3   S1020_1 - S1020_7   2008年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.3.S1020

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  • Operation Characteristics of Microwave Sources Based on Slow-Wave Interaction in Rectangular Corrugation 査読

    Y. Takamura, Y. Kazahari, H. Oe, K. Ogura, A. Sugawara, M. Hirata

    Plasma and Fusion Research   3   S1078_1 - S1078_5   2008年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.3.S1078

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  • Studies of a Weakly Relativistic Oversized Backward Wave Oscillator with Disk Cathode and Rectangular Corrugation 査読

    K. Ogura, Y. Miyazawa, S. Aoyama, Y. Takamura, S. Tamura, A. Sugawara

    IEEJ Transactions on Fundamentals and Materials   127 ( 11 )   681 - 686   2007年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1541/ieejfms.127.681

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  • Weakly Relativistic K-Band Oversized Backward Wave Oscillator with Bragg Reflector at Beam Entrance of Slow Wave Structure 査読

    K. Ogura, Y. Miyazawa, H. Tanaka, Y. Kiuchi, S. Aoyama, A. Sugawara

    Plasma and Fusion Research   2   S1041_1 - S1041_4   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.2.S1041

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  • Numerical study of instabilities induced by sheet electron beam on corrugated metal plate 査読

    Osamu Watanabe, Tsuguhiro Watanabe, Kazuo Ogura, Yoshinori Tatematsu, Yoriko Shima, Tsuyoshi Imai

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   46 ( 9A )   6051 - 6056   2007年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC APPLIED PHYSICS  

    It has been confirmed that the normal mode of a surface wave on a corrugated metal plate can be excited by a sheet electron beam. Two types of instabilities are analyzed numerically. One is the Cherenkov instability between the surface normal mode and the slow-space-charge mode of the electron beam. This instability is possibly absolute instability. The oscillation frequency of this instability can be controlled by the amplitude of the corrugation depth. The electron beam energy for this instability is determined by the ratio of the period length and the amplitude of the corrugation. Another is the Smith-Purcell-type instability. This instability is always convective-type instability. The oscillation frequency is higher than that of the above-mentioned Cherenkov instability and is in a broad band. The temporal growth rate of this instability is strongly reduced as the beam energy is reduced.

    DOI: 10.1143/JJAP.46.6051

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  • Dispersion characteristics of a rectangularly corrugated cylindrical slow-wave structure driven by a non-relativistic annular electron beam 査読

    M. R. Amin, K. Ogura

    IET MICROWAVES ANTENNAS & PROPAGATION   1 ( 3 )   575 - 579   2007年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INSTITUTION ENGINEERING TECHNOLOGY-IET  

    The dispersion relation of a rectangularly periodic cylindrical slow-wave structure (SWS) with an annular electron beam of energy < 100 keV and current around 200 A has been derived and solved numerically. This type of system is typically used in backward wave high-power microwave devices and linear accelerators. The dispersion relation is analysed for both the cold structure (for zero beam current) and structure with an annular beam. The cold structure dispersion relation is characterised by the real value of frequency and wavenumber. When an electron beam propagates through the structure and the beam energy and current are sufficient to produce instability, microwave radiation results. The strength of this radiation can be qualitatively approximated from the temporal growth rate of the instability, which is defined by the imaginary values of the frequency corresponding to the complex conjugate roots of the dispersion relation. The temporal growth rate for various beam parameters has been calculated. The proposed SWS is very easy to be fabricated and can be used in the real experiments for generating high-power microwaves.

    DOI: 10.1049/iet-map:20060279

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  • Overview of recent progress in the gamma 10 tandem mirror 査読

    T. Cho, H. Higaki, M. Hirata, H. Hojo, M. Ichimura, K. Ishii, K. Islam, A. Itakura, I. Katanuma, J. Kohagura, R. Minami, Y. Nakashima, T. Numakura, T. Saito, Y. Tatematsu, M. Yoshikawa, O. Watanabe, Y. Kubota, T. Kobayashi, Y. Yamaguchi, H. Saimaru, Y. Higashizono, Y. Miyata, S. Kiminami, K. Shimizu, M. Itou, T. Ikuno, A. Mase, Y. Yasaka, K. Sakamoto, M. Yoshida, A. Kojima, K. Ogura, N. Nishino, W. Horton, T. Kariya, T. Imai, V. P. Pastukhov, S. Miyoshi

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   11 - 16   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    (1) Four-time progress in ion-confining potentials phi(c) to 3.0 kV in comparison to phi(c) attained 1992-2002 is achieved in the hot-ion mode (T-i=several keV). A scaling of phi(c), which favorably increases with plug electron-cyclotron heating (ECH) powers (P-PECH), is obtained. (2) The advance in phi(c) leads to a finding of remarkable effects of radially sheared electric fields (dE(r)/dr) on turbulence suppression and transverse-loss reduction. (3) A weak decrease in phi(c) with increasing n(c) to similar to 10(19) m(-3) with the recovery of phi(c) with increasing P-PECH is obtained. (4) The first achievement of active control and formation of an internal transport barrier (ITB) has been carried out with the improvement of transverse energy confinement. Off-axis ECH in an axisymmetric barrier mirror produces a cylindrical layer with energetic electrons, which flow through the central cell and into the end region. The layer, which produces a localized bumped ambipolar potential Phi(c), generates a strong E-r shear and peaked vorticity with the direction reversal of E(r)xB sheared flow near the Phi(c) peak. Intermittent vortex-like turbulent structures near the layer are suppressed in the central cell. This results in T-e and T-i rises surrounded by the layer. The phenomena are analogous to those in tokamaks with ITB. (5) Preliminary central ECH (170 kW 20 ms) in a standard tandem-mirror operation raises T-e0 from 70 to 300 eV together with T-i perpendicular to 0 from 4.5 to 6.1 keV, and T-i//0 from 0.5 to 1.2 keV with tau(p0)=95 ms for phi(c) (=1.4 kV) trapped ions. The on-axis particle to energy confining ratio of tau(p0)/tau(E0) is observed to be 1.7 for phi(c) trapped ions (consistent with Pastukhov's theory) and 2.4 for central mirror-trapped ions with 240-kW plug ECH and 90-kW ICH (eta(ICH)similar to 0.3; nl(c)=4.5X10(17)m(-2)). (6) Recently, a 200 kW central ECH with 430 kW plug ECH produces stable central-cell plasmas (T-e=600 eV and T-i=6.6 keV) with azimuthal E(r)xB sheared flow. However, in the absence of the shear flow, hot plasmas migrate unstably towards vacuum wall with plasma degradation.

    DOI: 10.13182/FST07-A1305

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  • Improved performance of oversized backward wave oscillator driven by weakly relativistic electron beam 査読

    S. Aoyama, Y. Miyazawa, K. Ogura, A. Sugawara, M. Hirata

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   325 - 327   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    We improve the performance of the K-band oversized backward wave oscillator. The beam is annular and weakly relativistic. The beam voltage is less than 100 kV and the beam current is less than 500 A. The operation frequencies are in the range of 23-27 GHz. The electromagnetic field of the K-band B WO concentrates in the vicinity of the SWS wall and the electron beam should be propagated within a few mm from the wall. The uniformity of annular beam is also very important for the efficient beam coupling. First, we modify the oversized SWS so that the beam interaction point is shifted to the pi point. Secondly, we improve uniformity of the annular electron beam and the output power increases up to about 500 kW level.

    DOI: 10.13182/FST07-A1390

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  • Slow cyclotron and Cherenkov instabilities in weakly relativistic oversized backward wave oscillator 査読

    Y. Kiuchi, H. Tanaka, K. Ogura, O. Watanabe, T. Cho, Md. R. Amin

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   331 - 333   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    We analyze instabilities of oversized backward wave oscillator (BWO) designed for K-band operations in a weakly relativistic region (less than 100 kV). For the oversized BWO, the electromagnetic field is a surface wave localized near the waveguide wall. Instabilities due to the beam interactions with the surface wave are examined by considering three-dimensional beam perturbations. There exist the slow cyclotron and Cherenkov instabilities as in the case of non-oversized BWO. Nonaxisymmetric as well as axisymmetric instabilities are excited, even in the completely axisymmetric system. The growth rates of both modes are in the same order. The growth rates decrease exponentially if the beam is apart from the SWS wall.

    DOI: 10.13182/FST07-A1392

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  • Study of the effects of plasma-confining potentials using end-loss analysing systems 査読

    M. Hirata, T. Cho, J. Kohagura, T. Numakura, K. Shimizu, M. Ito, S. Kiminami, N. Morimoto, K. Hirai, T. Yamagishi, T. Ikuno, S. Namiki, Y. Miyata, R. Minami, K. Ogura, T. Kondoh, T. Kariya, T. Imai, S. Miyoshi

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   183 - 185   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    An application of electron-cyclotron heating with an off-axis resonance location produces a cylindrical layer with energetic electrons and facilitates the formation for a profile of plasma rotation with a radially localized high-vorticity layer. These phenomena are detected by several types of end-loss ions- and electrons-analyser. Formation of radial transport barrier has been observed in the vicinity of the high-vorticity layer in GAMMA 10.

    DOI: 10.13182/FST07-A1345

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  • Investigation of electron distribution functions in the plug region of the GAMMA 10 tandem mirror 査読

    J. Kohagura, T. Cho, M. Hirata, T. Numakura, Y. Tornii, S. Kiminami, N. Morimoto, K. Shimizu, M. Ito, T. Ikuno, S. Namiki, K. Hirai, T. Yamagishi, Y. Miyata, R. Minami, K. Ogura, T. Kariya, T. Imai, S. Miyoshi

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   204 - 207   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    Generalized scaling laws for the formation of plasma confining potentials are investigated to find the physics essentials common to representative tandem-mirror operational modes in GAMMA 10. These modes are characterized in terms of (i) a high-potential mode and (ii) a hot-ion mode. The potential-formation scalings in these modes are consolidated and generalized on the basis of the consistency with finding of the wider validity of Cohen's strong electron-cyclotron heating (ECH) theory covering over both modes. A plateau-shaped electron distribution function is observed when a plug electron-confining potential is formed in the hot ion mode of GAMMA 10, as predicted in terms of the strong ECH theory.

    DOI: 10.13182/FST07-A1351

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  • Effects of plasma confining potentials and the associated radially sheared electric fields on the plasma energy confinement 査読

    T. Numakura, T. Cho, J. Kohagura, M. Hirata, Y. Miyata, R. Minami, S. Kiminami, K. Shimizu, N. Morimoto, M. Itou, T. Ikuno, S. Namiki, T. Yamagishi, K. Hirai, K. Ogura, T. Kariya, T. Imai, S. Miyoshi

    FUSION SCIENCE AND TECHNOLOGY   51 ( 2T )   343 - 345   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER NUCLEAR SOCIETY  

    The effects of the plasma-confining potentials and the associated radially sheared electric fields on the central-cell electron energy confinement are theoretically and experimentally investigated in the GAMMA 10 tandem mirror. In particular, the scaling of the central-cell electron temperatures with electron-confining potentials is studied on the basis of the local energy-balance equation. The obtained theoretical scaling of electron temperatures with electron-confining potentials is then compared with the experimentally observed relation between these two parameters.
    Recently, by the use of new 0.5-M'W level gyrotrons in the plug region, four-time progress in the formation of the ion-confining potential phi(c) including a new record of 3 W has been achieved in a hot-ion mode having bulk-ion temperature T-i = several keV In the hot-ion mode, intermittent vortex-like turbulent structures are observed in the case without the gyrotron injections; in this case, radially produced weak shear of electric fields dE(r)/dr and appreciable transverse losses are observed. However, during the application of electron-cyclotron heatings, the associated potential rise produces a stronger shear in the central cell (dE(r)/dr = several 10 kV/m2) resulting in the disappearance of such intermittent turbulent vortices with plasma confinement improvement.
    In order to investigate the effect of the radially sheared electric fields on the electron energy confinement, the radial profiles of the thermal diffusivity are derived from the local power-balance analysis by the use of the data from the following various diagnostics in the above-described hot-ion mode. The obtained radial profiles of radial electric field and thermal diffusivity imply that the reduction of the thermal diffusivity is associated with the radially produced strong shear of electric fields.

    DOI: 10.13182/FST07-A1396

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  • Effects of Radially Sheared Electric Field on Turbulence Reduction Analyzed with End-Loss Analysing Systems

    HIRATA Mafumi, CHO Teruji, KOHAGURA Junko, NUMAKURA Tomoharu, KIMINAMI Serina, ITO Marie, MORIMOTO Naoyuki, HIRAI Katsuaki, YAMAGISHI Tooru, IKUNO Toshinori, NAMIKI Shohei, MIYATA Yoshiaki, MINAMI Ryutaro, OGURA Kazuo, KONDOH Takashi, KARIYA Tsuyoshi, IMAI Tsuyoshi, MIYOSHI Syoichi

    Plasma and Fusion Research   2   S1077 - S1077   2007年

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    記述言語:英語   出版者・発行元:The Japan Society of Plasma Science and Nuclear Fusion Research  

    Mirror devices, having open-ended regions, provide intrinsic important advantages in terms of the control of radial-potential or E<sub>r</sub> shear profiles on the basis of axial particle loss control for ambipolar potential formation. From the viewpoint of the mechanism investigation of radially localized transport-barrier formation, an idea of off-axis-resonant electron-cyclotron heating (ECH) is proposed and applied in the tandem mirror GAMMA 10, by the use of the aforementioned intrinsic advantage of mirror devices. The off-axis ECH produces a cylindrical layer with energetic electrons and facilitates the formation for a localized bumped ambipolar potential with a strong shear of radial electric fields E<sub>r</sub>. Remarkable effects of dE<sub>r</sub>/dr on the suppression of turbulent fluctuations with plasma confinement improvement are found by the use of signals of end-loss currents flowing from the central cell as well as the central-cell soft x ray. In association with the reduction of the fluctuations due to strong E<sub>r</sub> shear formation, increases in ion and electron temperatures are found.

    DOI: 10.1585/pfr.2.S1077

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  • Numerical examination of the operation modes of a weakly relativistic oversized backward wave oscillator 査読

    Hoshiyuki Yamazaki, Hirokazu Takagi, Hidekazu Tanaka, Kazuo Ogura

    JOURNAL OF PLASMA PHYSICS   72 ( 6 )   915 - 918   2006年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CAMBRIDGE UNIV PRESS  

    Backward wave oscillators (BWOs) have been studied as a candidate high-power microwave source. To increase the operation frequency, an oversized slow-wave Structure (SWS) is used. The operation at reduced voltage is preferable for practical applications. This work is aimed at numerically examining the operation mode of a weakly relativistic oversized BWO. We examine not only the axisymmetric transverse magnetic mode but also the non-axisymmetric hybrid modes of the oversized SWS. Both of them are candidates for the operation modes. These modes are surface waves whose fields are concentrated near the SWS wall. They overlap in frequency and are not separated by stop-bands. For an efficient beam interaction, the injected electron beam needs to be controlled more accurately than in the non-oversized SWS case.

    DOI: 10.1017/S0022377806005290

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  • Slow cyclotron instability due to surface modulation of an annular beam 査読

    Kazuo Ogura, Hoshiyuki Yamazaki, Yutaka Kiuchi, Md. Ruhul Amin

    JOURNAL OF PLASMA PHYSICS   72 ( 6 )   905 - 908   2006年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CAMBRIDGE UNIV PRESS  

    The Cherenkov instability used in slow-wave devices has been well studied in the literature. However, in previous analyses, the beam motion is restricted to the longitudinal direction assuming an infinitely strong magnetic field. For the finite strength magnetic field, the transverse beam perturbation cannot be ignored and leads to the slow cyclotron instability. Recently, a new version of self-consistent field theory considering three-dimensional perturbation has been developed based on a solid beam, in which the effect of the transverse perturbation appears as a surface charge at a fixed boundary. In the case of a thin annular beam, the boundary is modulated and is essentially different from the solid beam case. We propose a self-consistent field theory considering the moving modified boundary surface. The slow cyclotron instability due to the modulation of an infinitesimally thin annular electron beam is presented.

    DOI: 10.1017/S0022377806005095

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  • 01aC01P X線計測に基づくガンマ10の電位形成機構と電位・電場シアー形成効果の研究(プラズマ計測II、炉設計)

    小波蔵, 純子, 長, 照二, 平田, 真史, 沼倉, 友晴, 木南, 瀬里奈, 森本, 直道, 清水, 清昭, 伊藤, 万梨絵, 生野, 利典, 並木, 翔平, 平井, 克明, 山岸, 徹, 宮田, 良明, 南, 龍太郎, 小椋, 一夫, 假家, 強, 今井, 剛, 三好, 昭一

    プラズマ・核融合学会年会予稿集   0 ( 23 )   281   2006年11月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:社団法人プラズマ・核融合学会  

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  • Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector 査読

    M. Hirata, Y. Miyake, T. Cho, J. Kohagura, T. Numakura, K. Shimizu, M. Ito, S. Kiminami, N. Morimoto, K. Hirai, T. Yamagishi, Y. Miyata, Y. Nakashima, S. Miyoshi, K. Ogura, T. Kondoh, T. Kariya

    REVIEW OF SCIENTIFIC INSTRUMENTS   77 ( 10 )   10E719-1 - 10E719-3   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    For the purpose of end-loss-ion and -electron analyses in open-field plasmas, a compact-sized electrostatic end-loss-current detector is proposed on the basis of a self-collection principle for suppressing the effects of secondary-electron emission from a metal collector. For employing this specific method, it is worth noting that no further additional magnetic systems except the ambient open-ended magnetic fields are required in the detector operation. This characteristic property provides a compactness of the total detection system and availability for its use in plasma confinement devices without disturbing plasma-confining magnetic fields. The detector consists of a set of parallel metal plates with respect to lines of ambient magnetic forces of a plasma device for analyzing incident ion currents along with a grid for shielding the collector against strays due to the metal-plate biasing. The characterization experiments are carried out by the use of a test-ion-beam line along with an additional use of a Helmholtz coil system for the formation of open magnetic fields similar to those in the GAMMA 10 end region. The applications of the developed end-loss-current detector in the GAMMA 10 plasma experiments are demonstrated under the conditions with simultaneous incidence of energetic electrons produced by electron-cyclotron heatings for end-loss-plugging potential formation. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2338304

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  • Experimental estimation of the local energy balance of the potential-confining electrons in tandem-mirror plasmas 査読

    T. Numakura, T. Cho, J. Kohagura, M. Hirata, R. Minami, Y. Miyata, Y. Tomii, Y. Miyake, S. Kiminami, K. Shimizu, N. Morimoto, M. Itou, T. Imai, S. Miyoshi, K. Ogura

    REVIEW OF SCIENTIFIC INSTRUMENTS   77 ( 10 )   10F302-1 - 10F302-3   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Our proposed "matrix-type" semiconductor detectors are applied for studying the local energy balance of bulk electrons in the tandem-mirror GAMMA 10. The matrix-type detector array consists of compactly produced six "rows" having different thicknesses of thin dead layers (SiO2) on its surface. Each row has seven channel units ("columns") for measuring radiation profiles in the radial direction of plasmas. These various SiO2 layers are, thus, employed as "unbreakable ultrathin radiation-absorption filters" having various thicknesses to distinguish x rays from charge-exchange neutral particles and analyze the radial profiles of both plasma ion and electron temperatures simultaneously. The radial profiles of the energy confinement time and the thermal diffusivity obtained from the local energy balance analysis imply that the improvement of the plasma confinement is associated with the strong shear of radial electric fields due to a high plasma confining potentials. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2219404

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  • X-ray diagnostics for investigating electron distribution functions in the central cell of the GAMMA 10 tandem mirror 査読

    J. Kohagura, T. Cho, M. Hirata, T. Numakura, T. Fukai, Y. Tomii, S. Kiminami, N. Morimoto, T. Ikuno, S. Namiki, K. Shimizu, M. Ito, Y. Miyata, R. Minami, S. Miyoshi, K. Ogura, N. Saito, T. Saito, T. Kariya

    REVIEW OF SCIENTIFIC INSTRUMENTS   77 ( 10 )   10F332-1 - 10F332-3   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The quantum efficiency of an ultralow-energy-sensitive pure-Ge (ULE Ge) detector is investigated using synchrotron radiation from the storage ring at AIST especially for x-ray pulse-height analyses (PHAs), down to a few hundred eV. Several types of x-ray diagnostics such as x-ray PHA, x-ray absorption methods, and x-ray tomography using the ULE Ge detector, a NaI (Tl) detector, as well as a microchannel-plate tomography system are employed for investigating electron distribution functions and electron temperature profiles with preliminary central electron-cyclotron heating in the central cell of the GAMMA 10 tandem mirror. These measurements play an important role in studying an essential physics scaling of the electron temperature as a function of electron confining potential in tandem mirror plasmas. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2351922

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  • Numerical Study of Electromagnetic Surface Wave on Corrugated Metal Surface 査読

    O. Watanabe, T. Watanabe, K. Ogura, T. Imai, T. Cho

    Journal of Plasma and Fusion Research   1   025-1 - 025-2   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/pfr.1.025

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  • Progress in potential formation and findings in the associated radially sheared electric-field effects on suppressing intermittent turbulent vortex-like fluctuations and reducing transverse losses 査読

    T Cho, J Kohagura, M Hirata, T Numakura, H Higaki, H Hojo, M Ichimura, K Ishii, KM Islam, A Itakura, Katanuma, I, Y Nakashima, T Saito, Y Tatematsu, M Yoshikawa, Y Takemura, A Kojima, T Kobayashi, Y Yamaguchi, Y Miyata, N Yokoyama, Y Tomii, Y Miyake, S Kiminami, K Shimizu, Y Kubota, H Saimaru, Y Higashizono, A Mase, Y Yasaka, K Ogura, K Sakamoto, M Yoshida, VP Pastukhov, T Imai, S Miyoshi

    NUCLEAR FUSION   45 ( 12 )   1650 - 1657   2005年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    Following the 19th IAEA Fusion Energy Conference (Lyon, 2002), (1) three-time progress in the formation of ion-confining potential heights phi(c) including a record of 2.1 W in comparison to those attained 1992-2002 is achieved for tandem-mirror plasmas in the hot-ion mode with ion temperatures of several kiloelectronvolts. (2) The advance in the potential formation gives the bases for finding the remarkable effects of radially produced shear of electric fields E,, or non-uniform sheared plasma rotation on the suppression of intermittent vortex-like turbulent fluctuations. (i) Such a shear effect is visually highlighted by x-ray tomography diagnostics; that is, spatially and temporally intermittent vortex-like fluctuated structures are clearly observed as two-dimensionally reconstructed visual structures for the first time in kiloelectronvolt order ion-cyclotron heated plasmas having a weak shear in GAMMA 10. (ii) However, during the application of plug electron-cyclotron heatings (ECH), the associated potential rise produces a stronger shear (dE(r)/dr = several 10kVm(-2)) resulting in the disappearance of such intermittent turbulent vortices with plasma confinement improvement. X-ray observations also show elongation of a vortex structure from a circular into an ellipsoidal shape, as depicted in H-mode theories, with an outward shift. (3) For the physics interpretations and control of such potential and the associated shear formation, the validity of our proposed theory of the potential formation is extensionally tested under the conditions with auxiliary heating. The data described above fit well to the extended surfaces calculated from our proposed consolidated theory of the strong ECH theory (plateau formation) with Pastukhov's theory on energy confinement.

    DOI: 10.1088/0029-5515/45/12/021

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  • Study of Relations between the Spatial Structure of Potential-Trapped Electron Distribution Functions and the Physics Scaling Law of Plasma Confining Potentials

    M.,Hirata, T.,Cho, J.,Kohagura, T.,Numakura, T.,Fukai, N.,Yokoyama, S.,Tokioka, Y.,Tomii, Y.,Miyake, K.,Ogura, Y.,Suzuki, K.,Komiyama, H.,Saito

    Annual Report of National Institute for Fusion Science   April 2004-March 2005   463   2005年11月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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  • Performance of Weakly Relativistic Oversized Backward Wave Oscillators 査読

    Kazuo Ogura, Kiyofumi Komiyama, Masakazu Sakai, Daisuke Yamada, Hiroki Saito, Hoshiyuki Yamazaki

    IEEJ Transactions on Fundamentals and Materials   125 ( 9 )   733 - 738   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Performance of oversized backward wave oscillators (BWOs) is investigated. Due to the axial mode operation, there exists a critical value of beam energy for the oscillation, i.e., a starting energy. The output power depends on the beam radius and voltage. The maximum output powers are above 100 kW (K-band) and above 50 kW (Q-band). The corresponding quality factor Pf2 is about 6×104 [kW·GHz2]. By changing the condition at the SWS end, an enhanced performance of the K-band oversized BWO is observed in a low magnetic field region about 0.4 T. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

    DOI: 10.1541/ieejfms.125.733

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  • Nonaxisymmetric Instabilities in Periodically Corrugated Cylindrical Waveguide with Low Magnetic Field 査読

    Hoshiyuki Yamazaki, Makoto Iwai, Yoshitaka Suzuki, Hirokazu Takagi, Osamu Watanabe, Kazuo Ogura

    IEEJ Transactions on Fundamentals and Materials   125 ( 9 )   739 - 743   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Nonaxisymmetric Cherenkov and slow cyclotron instabilities in a backward wave oscillator are investigated by using a new version of self-consistent linear theory. The slow cyclotron instability as well as Cherenkov instability can be driven by an axial electron beam without any initial perpendicular velocity. In a low magnetic field region, the radial displacement of beam plays an important role in the beam interactions. The slow cyclotron instability becomes strong, when the perturbed cyclotron motion and the electromagnetic wave rotate in the same direction. The rotational direction of electromagnetic wave also affects the Cherenkov instability. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

    DOI: 10.1541/ieejfms.125.739

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  • Numerical Examination of Electromagnetic Field Properties in a Cylindrical Periodic Slow Wave Structure 査読

    H. Yamazaki, K. Ogura, T. Watanabe

    Journal of Plasma and Fusion Research SERIES   6   719 - 722   2004年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Study on Oscillation Starting Condition of K-Band Oversized Backward Wave Oscillator Driven by a Weakly Relativistic Electron Beam 査読

    K. Ogura, R. Yoshida, K. Komiyama, M. Sakai, H. Yamazaki

    Journal of Plasma and Fusion Research SERIES   6   703 - 706   2004年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Cherenkov and Slow Cyclotron Instability in Periodically Corrugated Cylindrical Waveguide with Low Magnetic Field Region 査読

    Hoshiyuki Yamazaki, Yuichiro Yamashita, Makoto Iwai, Yoshitaka Suzuki, Kazuo Ogura, Osamu Watanabe

    The transactions of the Institute of Electrical Engineers of Japan.A   124 ( 6 )   477 - 482   2004年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Cherenkov and slow cyclotron instabilities driven by an axially injected electron beam in periodically corrugated cylindrical waveguide are studied by using a new version of self-consistent linear theory considering three dimensional beam perturbations. For the bounded microwave systems, the self-consistent boundary conditions require all field components and the normal modes in the beam are hybrid of transverse magnetic (TM) and transverse electric (TE) modes, even in the axisymmetric case. The slow cyclotron instability as well as Cherenkov instability can be driven by the axially streaming electron beam without any initial perpendicular velocity. In the low magnetic field region, the charge caused by the radial displacement of the beam plays an important role in the beam interaction with the electromagnetic mode. The radial displacement become large by decreasing the magnetic field and the slow cyclotron instability becomes strong and compete with the Cherenkov instability. For the axisymmetric case, the Cherenkov instability is dominant and suppresses the slow cyclotron instability, On the other hand, the slow cyclotron instability becomes dominant and suppresses the Cherenkov instability, for the nonaxisymmetric mode with the left-hand circular polarization. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.

    DOI: 10.1541/ieejfms.124.477

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  • Experimental Demonstration of Mode Change in a Q-Band Oversized Backward Wave Oscillator due to Corrugation Number 査読

    Kazuo Ogura, Ryo Yoshida, Kiyofumi Komiyama, Masakazu Sakai, Hoshiyuki Yamazaki

    The transactions of the Institute of Electrical Engineers of Japan.A   124 ( 6 )   456 - 460   2004年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Operation mode of an oversized backward wave oscillator is studied experimentally, using an oversized slow-wave structure. The dispersion characteristics of the slow-wave structure are determined by the average radius, corrugation amplitude and pitch length of the periodic waveguide. The corrugation amplitude and the corrugation period mainly determine the upper cutoff frequency of the lowest mode. The lower cutoff frequency is determined by the average radius. In this work, a Q-band periodic slow-wave structure is fabricated from aluminum. The diameter of the slow-wave structure is about 4 times free space wavelength. The beam voltage is weakly relativistic, around 50 kV, and the beam current is in the range of 100 A. The output powers of several 10 kW are obtained in the Q-band, i.e., the estimated frequency is in the range of 34–41 GH. The output modes are examined by measuring the radiation patterns. Nonaxisymmetric as well as axisymmetric modes are observed. It is demonstrated for the first time that the nonaxisymmetric and axisymmetric operations of the oversized BWO can be controlled by changing the corrugation number of slow-wave structure. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.

    DOI: 10.1541/ieejfms.124.456

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  • Cherenkov instability due to unmagnetized electron beam in periodically corrugated waveguide 査読

    K Ogura, H Yamazaki, O Watanabe, MR Amin

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   42 ( 11 )   7095 - 7103   2003年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    Cherenkov instability driven by an unmagnetized electron beam in a periodically corrugated waveguide is studied by developing a new version of self-consistent linear theory. The conventional space-charge and cyclotron modes of magnetized beam degenerate in this case. The normal electromagnetic modes are pure transverse magnetic (TM) and transverse electric (TE) modes in axisymmetric cases and are hybrid modes having both TM and TE components in nonaxisymmetric cases. Using the developed linear theory, the axisymmetric and nonaxisymmetric Cherenkov instabilities due to the unmagnetized beam in the periodic system are examined numerically. The unmagnetized beam can excite the axisymmetric TM and nonaxisymmetric hybrid modes. A comparison of the numerically obtained results is made with those of the recent C-band Pasotron experiment.

    DOI: 10.1143/JJAP.42.7095

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  • Calibration experiments of He-3 neutron detectors for analyzing neutron emissivity in the hot-ion mode on the GAMMA 10 tandem mirror 査読

    J Kohagura, T Cho, M Hirata, H Watanabe, R Minami, T Numakura, M Yoshida, H Ito, Y Tatematsu, K Yatsu, S Miyoshi, K Ogura, T Kondoh, T Nishitani, M Kwon, AC England

    REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 3 )   1757 - 1760   2003年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Under the international fusion cooperating research, He neutron detectors in the GAMMA 10 tandem mirror are calibrated by the use of a Cf-252 spontaneous fission neutron source (8.96 x 10(4) n/s). The calibration experiments are carried out with a "rail system" placed along the, magnetic axis of the GAMMA 10 central-cell region, where hot ions in the plasma experiments with the bulk temperatures of similar to10 keV are produced. As compared to a previous neutron monitoring system with a BF3 detector in GAMMA 10, the present He-3 systems are designed with about two orders-of-magnitude higher neutron-counting efficiency for analyzing a neutron emissivity from the plasmas in a single plasma discharge alone. Two He-3 systems. are installed near the middle and the end of the central cell so as to identify the central-cell hot-ion axial profile. The filling pressure of He-3, the effective length, and the diameter of the detector are designed as 5 bar, 300 mm, and 50 mm, respectively. The detector output spectra are carefully analyzed by the use of a preamplifier, a shaping amplifier, as well as a multichannel analyzer for each He-3 detector. In the present article, the neutron-counting data from the two He-3 detectors due to the on-axis Cf-252 scan are interpreted in terms of the d(-2) intensity dependence (d being the distance between the detector and the neutron source) as well as the effects of the central-cell magnetic coils and the other machine structural components. (C) 2003 American Institute of Physics.

    DOI: 10.1063/1.1534402

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  • A novel method for simultaneous observations of plasma ion and electron temperatures using a semiconductor-detector array 査読

    T. Cho, T. Numakura, J. Kohagura, M. Hirata, R. Minami, H. Watanabe, T. Sasuga, Y. Nishizawa, M. Yoshida, S. Nagashima, Y. Nakashima, K. Ogura, T. Tamano, K. Yatsu, S. Miyoshi

    Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment   477 ( 1-3 )   204 - 209   2002年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A new method for a simultaneous observation of both plasma ion and electron temperatures is proposed using one semiconductor-detector array alone. This method will provide a new application of semiconductor-detector arrays for monitoring the key parameter set of nuclear-fusion triple product (i.e., ion temperatures, densities, and confinement time) as well as for clarifying physics mechanisms of energy transport between plasma ions and electrons under various plasma confining conditions. This method is developed on the basis of an alternative "positive" use of a semiconductor "dead layer"
    that is, an SiO2 layer is employed as a reliable ultra-thin energy analysis filter for low-energy charge-exchanged neutral particles from plasmas ranging in ion temperatures from 0.1 to several tens of kilo-electron-volts. Using recent fabrication techniques for the thin and uniform SiO2 layers of the order of tens to hundreds of angstrom, our computer simulation and its experimental verification show the availability of such semiconductors for distinguishing neutral particles (for ion temperatures) from X-rays (for electron temperatures). These are simultaneously emitted from the plasmas into semiconductor detectors
    however, we employ their quite different penetration lengths and the resultant different deposition depths and profiles in semiconductor materials. As a result, their output signals are distinguishable for these two different and fundamental species of plasmas. © 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(01)01899-X

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  • 30pA08P ガンマ10重水素バルクプラズマ核融合実験のための高効率He^3中性子計測器の絶対計測較正・最適化実験(プラズマ計測)

    長, 照二, 小波蔵, 純子, 渡辺, 裕之, 平田, 真史, 南, 龍太郎, 沼倉, 友晴, 吉田, 麻衣子, 永嶋, 賢史, 伊藤, 浩一, 石川, 正男, 北條, 仁士, 市村, 真, 石井, 亀男, 板倉, 昭慶, 片沼, 伊佐夫, 中嶋, 洋輔, 斉藤, 輝雄, 立松, 芳典, 吉川, 正志, 檜垣, 浩之, 谷津, 潔, 三好, 昭一, 小椋, 一夫, 近藤, 貴, 西谷, M, Kwon, M, England, A. C

    プラズマ・核融合学会年会予稿集   0 ( 18 )   177   2001年11月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:社団法人プラズマ・核融合学会  

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  • Self-consistent linear analysis of slow cyclotron and Cherenkov instabilities 査読

    O. Watanabe, K. Ogura, T. Cho, Md. R. Amin

    Physical Review E   63 ( 5 )   056503-1 - 056503-9   2001年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Physical Society (APS)  

    DOI: 10.1103/physreve.63.056503

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    その他リンク: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevE.63.056503/fulltext

  • Slow Wave Electron Cyclotron Maser Utilizing Periodically Corrugated Waveguide 査読

    Kazuo Ogura, Osamu Watanabe, Daizo Kamiyama

    Fusion Technology   39 ( 1T )   320 - 323   2001年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Nuclear Society  

    DOI: 10.13182/fst01-a11963470

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  • Normal Modes and Their High-Frequency Instabilities in Unbounded and Bounded Systems with Magnetied Electron Beam 査読

    O.Watanabe, K.Ogura

    Journal of Plasma and Fusion Research SERIES   3   601 - 604   2000年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Interaction of axially streaming electron beam with axisymmetric TM mode in a periodical slow wave structure with finite magnetic field 査読

    K Ogura, T Azegami, O Watanabe, T Watanabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   67 ( 10 )   3462 - 3470   1998年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Interaction between an axially streaming electron beam and an axisymmetric TM mode in a periodically corrugated waveguide is analyzed using a linear fluid model. Effect of the perpendic ular perturbation of the beam by a finite magnetic field is considered. There are two mechanisms of Cherenkov interaction between a beam and a TM mode. One is the conventional mechanism attributed to a longitudinal perturbation. The other is attributed to the vertical perturbation of the beam surface and is dominant in the low magnetic field region. The slow cyclotron mode on an axially streaming beam is able to interact with an axisymmetric TM mode only if beam surface modulation is taken into account. The Cherenkov and cyclotron interactions degenerate for zero magnetic fields. This interaction has higher growth rate compared to the conventional Cherenkov interaction in the region of high current and weakly relativistic energy.

    DOI: 10.1143/JPSJ.67.3462

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  • Determination of the Starting Energy for a Large Diameter K-band Backward Wave Oscillator 査読

    Md. R. Amin, Md. A. Goffar Khan, K. Ogura

    IE(I) Journal-ET   79   15 - 20   1998年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Experimental demonstration of a high-power slow-wave electron cyclotron maser based on a combined resonance of Cherenkov and anomalous Doppler interactions 査読

    K Ogura, MR Amin, K Minami, XD Zheng, Y Suzuki, WS Kim, T Watanabe, Y Carmel, VL Granatstein

    PHYSICAL REVIEW E   53 ( 3 )   2726 - 2729   1996年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    A slow-wave electron cyclotron maser consisting of an oversized corrugated waveguide and an axially injected electron beam has been demonstrated experimentally. At resonance, the output rf power is strongly enhanced. Maximum output power of 200 kW with an electronic efficiency of 4% at 19.5 GHz is obtained for an electron beam with voltage of 35 kV and current of 150 A. The oscillation is observed to be a periodic TM(01) mode. The enhancement of microwave radiation is estimated to be caused by the combined resonance of Cherenkov interactions and an anomalous Doppler shifted electron cyclotron interaction.

    DOI: 10.1103/PhysRevE.53.2726

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  • Plasma influence on the dispersion properties of finite-length, corrugated waveguides 査読

    A Shkvarunets, S Kobayashi, J Weaver, Y Carmel, J Rodgers, TM Antonsen, VL Granatstein, WW Destler, K Ogura, K Minami

    PHYSICAL REVIEW E   53 ( 3 )   R2045 - R2048   1996年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We present an experimental study of the electromagnetic properties of transverse magnetic modes in a corrugated-wall cavity filled with a radially inhomogeneous plasma. The shifts of the resonant frequencies of a finite-length, corrugated cavity were measured as a function of the background plasma density and the dispersion diagram was reconstructed up to a peak plasma density of 10(12) cm(-3). Good agreement with a calculated dispersion diagram is obtained for plasma densities below 5 X 10(11) cm(-3).

    DOI: 10.1103/PhysRevE.53.R2045

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  • Electromagnetic field properties of axial modes in a finite length X-band slow wave structure 査読

    MR Amin, K Ogura, T Kobayashi, Y Suzuki, T Watanabe

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   65 ( 2 )   627 - 634   1996年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The electromagnetic field properties of axisymmetric transverse magnetic (TM) modes in a specific slow wave structure (SWS) typically used in high power X-band backward wave oscillators are studied numerically. The dispersion relations, electric field distributions, and quality factors of the axial resonant modes are calculated. It is found that some of the axial modes can be switched from the volume modes to the surface ones by changing only the axial boundary of the SWS while the dispersion relations do not alter. This causes a drastic change in quality factors and can be of practical interest for controlling the coupling between beam and TM modes in high-power microwave devices. The calculated dispersion relations are verified experimentally for the TM(01) mode.

    DOI: 10.1143/JPSJ.65.627

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  • RESONANT ENHANCEMENT OF RADIATION FROM A BACKWARD-WAVE OSCILLATOR UTILIZING LARGE-DIAMETER CORRUGATED METAL STRUCTURE 査読

    MR AMIN, K MINAMI, K OGURA, XD ZHENG, T WATANABE

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   64 ( 11 )   4473 - 4484   1995年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    An experiment on a backward wave oscillator (BWO) utilizing a large diameter corrugated metal wall slow wave structure (SWS) has been presented. Measurements are made above and below the starting beam energy for conventional BWO operation. For the latter case, an excited noise-level backward wave at 20 GHz (TM(01) mode) is coupled at the ends of the SWS to a forward anomalous Doppler shifted electron cyclotron (EC) beam mode which amplifies the original oscillation by an amount of 50 dB. Resultant microwave output powers of 200 kW with 4.5% electronic efficiency are observed near the condition of resonant magnetic field for an electron beam with energy 35 keV. Unlike the well-known fast wave devices, our slow wave EC device is simple to operate utilizing an electron beam with dominant parallel velocity in a uniform magnetic field.

    DOI: 10.1143/JPSJ.64.4473

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  • STARTING ENERGY AND CURRENT FOR A LARGE-DIAMETER FINITE-LENGTH BACKWARD-WAVE OSCILLATOR OPERATED AT THE FUNDAMENTAL MODE 査読

    K MINAMI, K OGURA, Y AIBA, MR AMIN, XD ZHENG, T WATANABE, Y CARMEL, WW DESTLER, VL GRANATSTEIN

    IEEE TRANSACTIONS ON PLASMA SCIENCE   23 ( 2 )   124 - 132   1995年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    We study the starting conditions for a large diameter (diameter/wavelength = 4.8) finite length backward wave oscillator designed for 24-GHz operation at the fundamental TM(01) mode. This geometry is very promising for high power handling capability. We analyze two separate threshold conditions. First, finite length effects give rise to a threshold in electron beam energy below which oscillations cannot be sustained at any beam current. The second is the more familiar current threshold known as a start current. It is also found that the growth rate for the fundamental mode can be much larger than those of other higher order modes thus leading to coherent operation of large diameter sources free from mode competition.

    DOI: 10.1109/27.376576

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  • ANALYSIS OF THE ELECTROMAGNETIC-WAVES IN AN OVERMODED FINITE-LENGTH SLOW-WAVE STRUCTURE 査読

    MR AMIN, K OGURA, H KITAMURA, K MINAMI, T WATANABE, Y CARMEL, W MAIN, J WEAVER, WW DESTLER, VL GRANATSTEIN

    IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES   43 ( 4 )   815 - 822   1995年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    The electromagnetic fields of the higher order axial resonant modes in a slow wave structure are analyzed and found to have considerably different characteristics from those of the conventional fundamental mode. Here, the reflections at both ends produce axial resonant modes corresponding to axisymmetric transverse magnetic (TM) modes. The period of field modulation of some of the higher order axial modes is shorter than that of the usual mode in a cylindrical waveguide, which could be of practical interest for higher power, higher frequency operation of backward wave oscillators, A perturbation technique is used to ascertain the field distribution inside the resonant cavity, and the numerical results thus obtained are compared to some experimental data.

    DOI: 10.1109/22.375229

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  • EXPERIMENT ON A LARGE-DIAMETER PLASMA-FILLED BACKWARD-WAVE OSCILLATOR 査読

    K OGURA, K MINAMI, K KURASHINA, W KIM, T WATANABE, K ISHII, S SUGITO

    FUSION ENGINEERING AND DESIGN   26 ( 1-4 )   365 - 373   1995年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA LAUSANNE  

    A large-diameter plasma-filled backward-wave oscillator (BWO) is investigated experimentally. The parameters of slow wave structure are chosen so that the oscillation frequency is about 20 GHz at 60 keV beam energy. Plasma is produced by the beam and has favorable effects for beam propagation and Cerenkov oscillations. The output power of the BWO with plasma is observed to be three to six times that of vacuum BWO. The power level is several kilowatts and the efficiency is about 0.01%. For Cerenkov oscillations of a large-diameter BWO, the beam energy mainly determines the starting conditions for oscillation. The output power is strongly enhanced when the guiding magnetic field approaches the fundamental electron cyclotron resonance. This mechanism is closely related to the anomalous Doppler cyclotron resonance. The maximum power of 480 kW with an efficiency of 5% is achieved even for a relatively low beam energy of 60 keV.

    DOI: 10.1016/0920-3796(94)00203-J

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  • ELECTROMAGNETIC PROPERTIES OF OPEN AND CLOSED OVERMODED SLOW-WAVE RESONATORS FOR INTERACTION WITH RELATIVISTIC ELECTRON-BEAMS 査読

    W MAIN, Y CARMEL, K OGURA, J WEAVER, GS NUSINOVICH, S KOBAYASHI, JP TATE, J RODGERS, A BROMBORSKY, S WATANABE, MR AMIN, K MINAMI, WW DESTLER, VL GRANATSTEIN

    IEEE TRANSACTIONS ON PLASMA SCIENCE   22 ( 5 )   566 - 577   1994年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    Specific slow wave structures are needed in order to produce coherent Cherenkov radiation in overmoded relativistic generators. The electromagnetic characteristics of such slow wave, resonant, finite length structures commonly used in relativistic backward wave oscillators have been studied both experimentally and theoretically. In experiments, perturbation techniques were used to study both the fundamental and higher order symmetric transverse magnetic (TM) modes. Finite length effects lead to end reflections and quantization of the wave number. The effects of end reflections in open slow wave structures were found from the spectral broadening of the discrete resonances of the different axial modes. The measured axial and radial field distributions are in excellent agreement with the results of a 2-D code developed for the calculation of the fields in these structures.

    DOI: 10.1109/27.338269

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  • HIGH-POWER BACKWARD-WAVE OSCILLATOR DRIVEN BY AN INTENSE RELATIVISTIC ELECTRON-BEAM WITH TAPERED SLOW-WAVE STRUCTURE FOR IMPROVED PERFORMANCES 査読

    T WATANABE, K OGURA, S WATANABE, K MINAMI

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   331 ( 1-3 )   134 - 139   1993年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A new theoretical and computational method, which can analyze uniformly the working of slow wave oscillators with various shapes of the waveguide, is developed. Time evolution of nonlinear boundary value problems in 2D space are reduced to 1D space boundary value problems by the power expansion method, and the reduced equations can be solved numerically by the new numerical scheme HIDM (higher order implicit difference method) with high accuracy. Dynamics of the backward wave oscillator driven by an intense relativistic electron beam are analyzed by this method. It is found that a throttled shape waveguide is preferable to obtain uniform output power of microwave.

    DOI: 10.1016/0168-9002(93)90030-L

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  • ABSOLUTE INSTABILITY OF LOW-FREQUENCY ELECTROMAGNETIC-WAVES IN A PLASMA WAVE-GUIDE WITH PERIODIC BOUNDARIES 査読

    K OGURA, MM ALI, K MINAMI, S WATANABE, Y KAN, Y AIBA, A SUGAWARA, T WATANABE

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   61 ( 11 )   4022 - 4032   1992年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    The linear dispersion relation of low frequency electromagnetic plasma waves in a corrugated plasma waveguide is analyzed successfully for a particular model in which difficulties for satisfying Floquet theorem rigorously are overcome. The resultant absolute instabilities are investigated numerically in some detail.

    DOI: 10.1143/JPSJ.61.4022

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  • ANALYSIS ON FIELD LINES AND POYNTING VECTORS IN CORRUGATED WALL WAVE-GUIDES 査読

    K OGURA, K MINAMI, MM ALI, Y KAN, T NOMURA, Y AIBA, A SUGAWARA, T WATANABE

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   61 ( 11 )   3966 - 3976   1992年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Field patterns and Poynting vectors of TM01 mode in sinusoidally corrupted waveguides are analyzed numerically. It is shown that a plasma column new the axis excludes the rf electric field lines towards the peripheral region, resulting in Poynting vectors in the axial direction there. The excitation of TM01 mode in corrugated waveguides is shown to be classified into two cases; surface and the volume waves. A possible physical explanation for the enhanced radiation observed previously from plasma filled backward wave oscillators is tried from the present results.

    DOI: 10.1143/JPSJ.61.3966

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  • A THEORY ON THE X-RAY-SENSITIVITY OF A SILICON SURFACE-BARRIER DETECTOR INCLUDING A THERMAL CHARGE-DIFFUSION EFFECT 査読

    T CHO, M HIRATA, E TAKAHASHI, T TERAJI, N YAMAGUCHI, K MATSUDA, A TAKEUCHI, J KOHAGURA, K OGURA, T KONDOH, A OSAWA, K YATSU, T TAMANO, S MIYOSHI

    JOURNAL OF APPLIED PHYSICS   72 ( 8 )   3363 - 3373   1992年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    An analytical method based on a new theoretical model for the x-ray energy responses of silicon surface-barrier (SSB) detectors has been proposed. This method may address a recent confusing issue in the x-ray detection characteristics of SSB semiconductor detectors; that is, the x-ray responses of SSB detectors as well as p-i-n diodes used in underbiased operations were recently found to be contrary to the commonly held belief that the x-ray sensitivity of an SSB detector is determined by the thickness of the depletion layer. The model presented includes a signal contribution from thermally diffusing charge that is created in the field-free substrate region within a diffusion length from the depletion layer along with a signal contribution from charge created in the depletion layer. This model predicts a large signal contribution from the charge-diffusion effect on the SSB responses to high-energy x rays. Formulas and calculated results supporting SSB calibration data have been represented. These analytical methods might be developed to apply the analyses and predictions of energy responses of various types of silicon detectors including p-i-n diodes as well as charge-coupled devices.

    DOI: 10.1063/1.351458

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  • ANALYSIS OF STARTING CURRENTS IN A BACKWARD-WAVE OSCILLATOR WITH FINITE STRUCTURE LENGTH 査読

    K MINAMI, MM ALI, K OGURA, W KIM, T WATANABE

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   61 ( 10 )   3566 - 3575   1992年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN  

    Starting current conditions for initiating radiation from a backward oscillator with finite structure length and with non-zero end reflections are analyzed numerically. Because of the leak of radiation at both ends, the beam starting current for initiating oscillation cannot be Zero. Various models for computing the condition are compared and discussed from the stand point of actual experiments.

    DOI: 10.1143/JPSJ.61.3566

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  • X-RAY-DETECTOR CHARACTERIZATION AND APPLICATIONS FOR PLASMA RESEARCH 査読

    T CHO, M HIRATA, E TAKAHASHI, N YAMAGUCHI, T KONDOH, T KUWABARA, K YATSU, K OGURA, S AOKI, H MAEZAWA, S MIYOSHI

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   66 ( 4 )   485 - 491   1992年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Using synchrotron radiation, the detection characteristics of microchannel plates, silicon surface barrier detectors and gold photocathodes are investigated; in particular, the detailed structures of the detection efficiency including an extended X-ray absorption fine structure (EXAFS), an X-ray absorption near-edge structure (XANES) and a chemical shift is reported along the with discussion on the physical mechanisms. Also, the applications of these detectors to X-ray tomography diagnostics for the observation of the cross-sections of fusion-oriented tandem-mirror plasmas are described. These data give information on the spatial distribution of the hot electrons which play an important role in the formation of thermal-barrier potentials phi(b). Also, the tomographic reconstructed X-ray data in the central cell show the effect of phi(b) formation on the improvement in the central-cell electron confinement for the first time.

    DOI: 10.1016/0168-583X(92)95423-O

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  • EFFECT OF BEAM ENERGY SPREAD ON RADIATION INTENSITY IN A HIGH-POWER BACKWARD-WAVE OSCILLATOR WITH FINITE LENGTH 査読

    T WATANABE, K OGURA, K MINAMI, M ALI

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   61 ( 4 )   1136 - 1140   1992年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN  

    Numerical analysis for radiation level in a high-power backward wave oscillator with a finite-length slow-wave structure with end reflections has been made using an algorithm called the higher-order implicit difference method (HIDM). Spatial and temporal evolutions of a small localized disturbance in an RF field are followed by relativistic fluid equations and Maxwell equations. The radiation intensity of the oscillation decreases substantially with increasing energy spread beyond 10% of the beam.

    DOI: 10.1143/JPSJ.61.1136

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  • LINEAR-ANALYSIS OF A FINITE LENGTH PLASMA-FILLED BACKWARD-WAVE OSCILLATOR 査読

    MM ALI, K OGURA, K MINAMI, T WATANABE, WW DESTLER, VL GRANATSTEIN

    PHYSICS OF FLUIDS B-PLASMA PHYSICS   4 ( 4 )   1023 - 1032   1992年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Absolute instability in a plasma-filled backward wave oscillator with sinusoidally corrugated slow wave structure driven by an intense relativistic electron beam has been analyzed numerically. The maximum spatial growth rate of the plasma-filled waveguide is found to be larger than that of an optimally designed vacuum structure. The excitation of a finite length structure is investigated. Although the spatial growth rates obtained in the linear theory increase with plasma density in the finite length plasma-filled structure for the fundamental TM01 mode of oscillation, negative global spatial growth rates prevent the coherent oscillation for intermediate ranges of plasma density, beam current, and even for structure length.

    DOI: 10.1063/1.860225

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  • X-RAY STUDIES OF VARIOUS SHAPES OF ELECTRON-VELOCITY DISTRIBUTION-FUNCTIONS AND OF ELECTRON CONFINEMENT AFFECTED BY KILOVOLT-RANGE ELECTROSTATIC POTENTIALS 査読

    T CHO, M HIRATA, E TAKAHASHI, K OGURA, K MASAI, N YAMAGUCHI, T KONDOH, K MATSUDA, H HOJO, M INUTAKE, K ISHII, Y KIWAMOTO, A MASE, T SAITO, K YATSU, S MIYOSHI

    PHYSICAL REVIEW A   45 ( 4 )   2532 - 2545   1992年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    Several types of x-ray diagnostics, such as x-ray energy spectrum analyses, x-ray absorption methods, and x-ray tomographic reconstructions using various types of x-ray detectors (i.e., a Si(Li), a pure Ge, a NaI(T1), Si surface-barrier detectors, as well as microchannel plates) have been employed for obtaining various shapes of electron-velocity distribution functions as well as their spatial profiles: (i) a plateau-shaped electron-velocity distribution function in the plug region, supporting a scaling theory between thermal-barrier potentials and ion-confining potentials (Cohen's strong electron-cyclotron heating theory); (ii) mirror-trapped 60-keV relativistic Maxwellian electrons in the thermal-barrier region; and (iii) two-component Maxwellian electrons in the central cell have been observed in the tandem-mirror GAMMA 10. During experiments with thermal barriers, it has been observed that the bulk-electron temperature and its evolution with time in the central cell are quite different from the electron energy and its temporal evolution in the plug region. These differences as well as the different shape of the electron-velocity distribution function in each region have clearly demonstrated the existence of a thermal-isolation effect due to the thermal barriers between the central cell and the plug region. X-ray tomography data in these three regions have shown good axisymmetric radial profiles peaked on the magnetic axis; this axisymmetric shape is useful for reducing nonambipolar radial particle losses. Furthermore, the validity of the Pastukhov theory for electron-energy confinement that is enhanced due to the formation of thermal-barrier potentials has been demonstrated using the electron-energy balance analyses. These data have represented a good electron-energy confinement capability due to the formation of thermal barriers.

    DOI: 10.1103/PhysRevA.45.2532

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  • A New Theory and Its Application to the Fitting of the X-ray Energy-Response Data of Silicon Surface-Barrier Detectors

    T., Cho, E., Takahashi, M., Hirata, N., Yamaguchi, T., Teraji, J., Kohagura, T., Tamano, S., Miyoshi, K., Ogura, S., Aoki, H., Maezawa, X, W. Zhang

    Photon Factory Activity Report 1992   10   376   1992年1月

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    記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)   出版者・発行元:National Laboratory for High Energy Physics  

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  • EQUILIBRIA OF RF TOKAMAK PLASMAS DURING CURRENT START-UP 査読

    T MAEKAWA, K OGURA, H TANAKA, M NAKAMURA, Y TERUMICHI, S TANAKA

    PLASMA PHYSICS AND CONTROLLED FUSION   33 ( 14 )   1723 - 1733   1991年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Equilibria of r.f. Tokamak plasmas during lower hybrid (LH) wave-driven current start-up experiments in the WT-2 and WT-3 Tokamaks are studied by comparing spatial profiles of tail and bulk electrons with simple model equilibria for the electron tail. When the plasma current I(p) is smaller than the Alfven critical current I(A), the confinement areas of the tail and bulk electrons are not coincident. The cross-section of the outermost flux surface is always found to be larger than the tail cross-section. Particularly in the case of the small Tokamak WT-2 (a(L) = 9 cm) is the outermost flux surface coincident with the limiter circle and much larger than the tail cross-section, indicating that good confinement of bulk electrons which carry LH waves and provide electrons to the tail is crucial for r.f. current start-up.

    DOI: 10.1088/0741-3335/33/14/002

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  • NONINDUCTIVE CURRENT DRIVE USING 2ND HARMONIC ELECTRON-CYCLOTRON WAVES ON THE WT-3 TOKAMAK 査読

    H TANAKA, K OGURA, A ANDO, S IDE, M IIDA, K HANADA, T MINAMI, M YOSHIDA, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   31 ( 9 )   1673 - 1687   1991年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    A plasma current of up to 70 kA has been sustained in WT-3 discharges by second harmonic (2-OMEGA-e) electron cyclotron (EC) waves alone, with zero loop voltage, after shutting off the Ohmic heating power. Further, in the case of high power EC wave injection, ramp-up discharges have been obtained. Pulse height analysis of hard X-rays in the line of sight at various angles to the toroidal field shows that the velocity distribution function of the high energy tail electrons is asymmetric in the toroidal direction. The 2-OMEGA-e EC wave is mainly absorbed by the tail electrons, and a 2-OMEGA-e EC driven current is generated by enhancing the asymmetry of the distribution. The figure of merit of 2-OMEGA-e EC current drive (ECCD) is eta-EC(2) = (3.2-6.4) x 10(-2) (10(19) A/W.m2), which is one order of magnitude smaller than that of lower hybrid current drive in WT-3. This low value of eta-EC(2) can be attributed to low confinement of the current carrying, high energy tail electrons produced by 2-OMEGA-e ECCD.

    DOI: 10.1088/0029-5515/31/9/006

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  • LINEAR-ANALYSIS OF A LOCALIZED PLASMA-LOADED BACKWARD-WAVE OSCILLATOR DRIVEN BY AN ANNULAR INTENSE RELATIVISTIC ELECTRON-BEAM 査読

    MM ALI, K MINAMI, S AMANO, K OGURA, T WATANABE

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   60 ( 8 )   2655 - 2664   1991年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN KIKAI-SHINKO BUILDING  

    The linear theory of electromagnetic radiation from a localized plasma-loaded backward wave oscillator with sinusoidally corrugated slow wave structure driven by an annular intense relativistic electron beam has been derived and analyzed numerically. The enhanced radiation from a plasma-loaded structure is attributed to the increase in the spatial growth rate of the absolute instability. The backward wave oscillator instability without plasma is found to be most effective in a case where the beam travels near the wall of the slow wave structure. For the given number of plasma particles per unit length of the structure, the decrease in the plasma column radius enhances the output radiation.

    DOI: 10.1143/JPSJ.60.2655

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  • STUDY OF THE FAST ELECTRON-DISTRIBUTION FUNCTION IN LOWER HYBRID AND ELECTRON-CYCLOTRON CURRENT DRIVEN PLASMAS IN THE WT-3 TOKAMAK 査読

    K OGURA, H TANAKA, S IDE, M IIDA, K HANADA, M YOSHIDA, T MINAMI, T CHO, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   31 ( 6 )   1015 - 1033   1991年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    The distribution function f(--&gt; p) of fast electrons produced by lower hybrid current drive (LHCD) is investigated in the WT-3 tokamak, using a combination of measurements of the hard X-ray (HXR) angular distribution with respect to the toroidal magnetic field and observations of the HXR radial profile. The data obtained indicate the formation of a plateau-like region in f(--&gt;p) which corresponds to a region of resonant interaction between the lower hybrid (LH) wave and the electrons. The energy of the fast electrons in the peripheral plasma region is observed to be higher than that in the central plasma region under operational conditions with a high plasma current (I(p) greater-than-or-equal-to 80 kA). At low current (I(p) less-than-or-similar-to 50 kA), however, the energy of fast electrons is constant along the plasma radius. In the current ramp-up phase, fast electrons are generated in the directions normal to and opposite to the LH wave propagation. The latter case is ascribed to a negatively biased toroidal electric field induced by the current ramp-up. To study the characteristic change of f(--&gt;p) for various current drive mechanisms, HXR measurements are performed in electron cyclotron current driven (ECCD) plasma and in Ohmic heating (OH) plasma. In ECCD plasma, the perpendicular energy of fast electrons increases, which indicates that fast electrons are accelerated perpendicularly by electron cyclotron heating. In both LHCD and ECCD plasmas, fast electrons flow in the direction opposite to the wave propagation, while no such fast electrons are formed in OH plasma.

    DOI: 10.1088/0029-5515/31/6/002

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  • TEMPORAL BEHAVIOR OF THE POTENTIAL CONFINED ELECTRONS IN THE CENTRAL CELL AND IN THE PLUG REGION DURING A PERIOD WITH THERMAL BARRIERS 査読

    M HIRATA, T CHO, E TAKAHASHI, K MASAI, K OGURA, K KOGANEZAWA, N YAMAGUCHI, T KATO, T KONDOH, K ISHII, T SAITO, Y KIWAMOTO, K YATSU, S MIYOSHI

    NUCLEAR FUSION   31 ( 4 )   752 - 756   1991年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    An increase with time of the central-cell electron temperature during a period with thermal barrier potentials has been observed. The increase is explained by an improvement of the electron energy confinement due to the presence of thermal barriers. Different evolutions of the electron energy in the plug region have been observed; these are closely related with the variation in time of the confining potential of the plug electrons. The observed behaviour of the potential confined electrons provides the first data set for the evolution of the effect of thermal isolation caused by the formation of a thermal barrier in the kilovolt range.

    DOI: 10.1088/0029-5515/31/4/012

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  • COMPUTER-TOMOGRAPHY OF M=1 MODE DURING SAWTOOTH OSCILLATION WITH 3 SOFT-X-RAY DETECTOR ARRAYS ON THE WT-3 TOKAMAK 査読

    K HANADA, K OGURA, S IDE, H TANAKA, M IIDA, T ITO, M IWAMASA, M YOSHIDA, T MINAMI, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    PLASMA PHYSICS AND CONTROLLED FUSION   32 ( 14 )   1289 - 1299   1990年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Soft X-rays (SXRs) emitted from plasma in the WT-3 Tokamak were measured by three SXR detector arrays, viewing the plasma from three different angles. From these experimental data, we reconstructed the two dimensional (2-D) contour of constant SXR emissivity as a function of time, using the technique of computer tomography (CT). Computer simulation results show that data from three or more sets of detector arrays are required to reconstruct the 2-D emissivity structure with sufficient accuracy to distinguish Kadomtsev's model from the quasi-interchange (Wesson's) model of sawtooth crash. Further, it is shown that if the noise amplitude is more than 1.5%, reconstruction of the real 2-D SXR emissivity structure is difficult.

    DOI: 10.1088/0741-3335/32/14/003

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  • ABSOLUTE INSTABILITY FOR ENHANCED RADIATION FROM A HIGH-POWER PLASMA-FILLED BACKWARD-WAVE OSCILLATOR 査読

    MM ALI, K MINAMI, K OGURA, T HOSOKAWA, H KAZAMA, T OZAWA, T WATANABE, Y CARMEL, VL GRANATSTEIN, WW DESTLER, RA KEHS, WR LOU, D ABE

    PHYSICAL REVIEW LETTERS   65 ( 7 )   855 - 858   1990年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    DOI: 10.1103/PhysRevLett.65.855

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  • LINEAR-THEORY OF ELECTROMAGNETIC-WAVE GENERATION IN A PLASMA-LOADED CORRUGATED-WALL RESONATOR 査読

    K MINAMI, Y CARMEL, VL GRANATSTEIN, WW DESTLER, W LOU, DK ABE, RA KEHS, MM ALI, T HOSOKAWA, K OGURA, T WATANABE

    IEEE TRANSACTIONS ON PLASMA SCIENCE   18 ( 3 )   537 - 545   1990年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    DOI: 10.1109/27.55925

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  • TOROIDAL PLASMA CURRENT STARTUP AND SUSTAINMENT BY LOWER HYBRID WAVES IN THE WT-3 TOKAMAK 査読

    K OGURA, H TANAKA, S IDE, M IIDA, K HANADA, M YOSHIDA, T MINAMI, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   30 ( 4 )   611 - 624   1990年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/30/4/003

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  • OBSERVATION OF A PLATEAU ELECTRON-DISTRIBUTION FUNCTION DUE TO ELECTRON-CYCLOTRON HEATING FOR AN EFFICIENT PLUG POTENTIAL FORMATION 査読

    T CHO, M HIRATA, K OGURA, E TAKAHASHI, T KONDOH, N YAMAGUCHI, K MASAI, K HAYASHI, KATANUMA, I, K ISHII, T SAITO, Y KIWAMOTO, K YATSU, S MIYOSHI

    PHYSICAL REVIEW LETTERS   64 ( 12 )   1373 - 1376   1990年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    DOI: 10.1103/PhysRevLett.64.1373

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  • INVESTIGATION OF HIGH-ENERGY ELECTRONS IN LOWER HYBRID CURRENT DRIVE PLASMA WITH ELECTRON-CYCLOTRON EMISSION MEASUREMENT IN WT-3 査読

    S IDE, K OGURA, H TANAKA, M IIDA, K HANADA, T ITOH, M IWAMASA, H SAKAKIBARA, T MINAMI, M YOSHIDA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   29 ( 8 )   1325 - 1338   1989年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/29/8/009

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  • 高周波電流駆動における高速電子の形成と速度分布関数

    小椋 一夫

    1989年5月

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    記述言語:日本語   掲載種別:学位論文(その他)  

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  • WT‐3トカマクにおける高周波によるプラズマ電流の立ち上げと保持

    小椋 一夫, 田中 仁, 井手 俊介, 飯田 素身, 花田 和明, 伊藤 岳彦, 岩政 幹人, 前川 孝, 曄道 恭, 田中 茂利

    核融合研究   61 ( 2 )   106 - 127   1989年

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    記述言語:日本語   出版者・発行元:The Japan Society of Plasma Science and Nuclear Fusion Research  

    The toroidal plasma current is started up by rf power alone and is ramped up to above 20 kA in a low density plasma. The fraction ε<SUB><I>R</I></SUB> of injected LHW power is converted into poloidal magnetic field energy and its maximum value is about 5 %. For high density cases, a quasi-steady state discharge is obtained and the figure of merit η<SUB><I>CD</I></SUB> for steady current drive by LHW is about 0.04 × 10<SUP>19</SUP> (A·m<SUP>-2</SUP>/W). The direct loss of fast electrons from the plasma is very large and results in the low ε<SUB><I>R</I></SUB> and η<SUB><I>CD</I></SUB> in our experiments.

    DOI: 10.1585/jspf1958.61.106

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    その他リンク: https://jlc.jst.go.jp/DN/JALC/00225263143?from=CiNii

  • ELECTRON-CYCLOTRON CURRENT DRIVE AT THE 2ND HARMONIC IN THE WT-3 TOKAMAK 査読

    H TANAKA, A ANDO, K OGURA, S IDE, M IIDA, K OHO, S OZAKI, K IWAMURA, A YAMAZAKI, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    PHYSICAL REVIEW LETTERS   60 ( 11 )   1033 - 1036   1988年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    DOI: 10.1103/PhysRevLett.60.1033

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  • Electron cyclotron current drive on WT-III by a56 GHz gyrotron 査読

    Y. Terumichi, H. Tanaka, A. Ando, K. Ogura, S. Ide, M. Iida, K. Oho, S. Ozaki, K. Iwamura, A. Yamazaki, M. Nakamura, T. Maekawa, S. Tanaka

    International Journal of Electronics   65 ( 3 )   691 - 697   1988年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Electron cyclotron current drive (EC-CD) experiments have been carried out atthe fundamental and the second harmonics onthe WT-III tokamak using extraordinary moderadiation at 56 GHz launched from the low field side. The EC driven current of 24 kAisattained at the power level of 100 kW and the plasma with the density of 2 ×1012cm−3 and the electron temperature of several hundredseV can be sustained during the EC pulse. The efficiency of EC-CD is 1·0 × 10−2 (1019m−2 A W−1) atthe fundamental and 3·5 × 10−2 at the second harmonic. Theunidirectional high energy electrons in theinitial target plasma is necessary for EC-CD. © 1988 Taylor &amp
    Francis Group, LLC.

    DOI: 10.1080/00207218808945266

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  • Electron Cyclotron Current Drive Experiments in the WT-3 Tokamak 査読

    H.Tanaka, K.Ogura, A.Ando, S.Ide, M.Iida, K.Iwamura, A.Yamazaki, T.Itoh, M.Iwamasa, K.Hanada, M.Nakamura, T.Maekawa, Y.Terumichi, S.Tanaka

    Proc. of the 15th European Conference on Controlled Fusion and Plasma Heating   1031   1988年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Electron Cyclotron Emission from Lower Hybrid Current Drive Plasma on the WT-3 Tokamak 査読

    Shunsuke Ide, Motomi Iida, Kazuo Ogura, Hitoshi Tanaka, Akira Yamazaki, Kazuaki Iwamura, Kazuaki Hanada, Takehiko Itou, Mikito Iwamasa, Yasushi Terumichi, Shigetoshi Tanaka, Takashi Maekawa, Akira Ando, Masahiko Nakamura

    Journal of the Physical Society of Japan   57 ( 8 )   2605 - 2608   1988年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Electron cyclotron emission (ECE) from the lower hybrid current drive (LHCD) as well as the ohmic heating (OH) plasmas in WT-3 were measured along the horizontal chord in the equatorial plane and the vertical chord where the magnitude of the toroidal field is constant, respectively. Measurements show that the high energy tail electrons carrying the plasma current build up within 10 msec after the injection of the lower hybrid wave. The ECE spectrum from the LHCD plasma in a quasi-steady state can be fitted with a numerically calculated spectrum assuming that the electron velocity distribution function is Maxwellian with the temperature T=50 keV. © 1988, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI: 10.1143/JPSJ.57.2605

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  • OBSERVATION OF HOT-ELECTRONS PRODUCED BY SECOND-HARMONIC ELECTRON-CYCLOTRON HEATING IN THE AXISYMMETRICAL TANDEM MIRROR GAMMA-10 査読

    T CHO, T KONDOH, M HIRATA, A SAKASAI, N YAMAGUCHI, A MASE, Y KIWAMOTO, A HIROSE, K OGURA, S TANAKA, S MIYOSHI

    NUCLEAR FUSION   27 ( 9 )   1421 - 1438   1987年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/27/9/006

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  • CYCLIC TOKAMAK OPERATION IN THE WT-2 DEVICE 査読

    M NAKAMURA, K OGURA, A ANDO, H TANAKA, M IIDA, S IDE, K OHO, S OZAKI, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   27 ( 5 )   779 - 785   1987年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/27/5/007

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  • Electron Cyclotron and Lower Hybrid Current Drive Experiments in the WT-III Tokamak 査読

    S.Tanaka, Y.Terumichi, T.Maekawa, M.Nakamura, A.Ando, K.Ogura, H.Tanaka, M.Iida, S.Ide, K.Oho, S.Ozaki, K.Iwamura, A.Yamazaki, H.Takase

    Proc. of the 14th European Conference on Controlled Fusion and Plasma Physics   3   886   1987年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • PLASMA CURRENT SUSTAINMENT AND RAMP-UP BY ELECTRON-CYCLOTRON WAVES IN THE WT-2 TOKAMAK 査読

    A ANDO, K OGURA, H TANAKA, M IDA, S IDE, K OHO, S OZAKI, M NAKAMURA, T CHO, T MAEKAWA, Y TERUMICHI, S TANAKA

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   55 ( 12 )   4259 - 4271   1986年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN  

    DOI: 10.1143/JPSJ.55.4259

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  • TOROIDAL PLASMA PRODUCTION BY ELECTRON-CYCLOTRON HEATING IN THE WT-2 DEVICE 査読

    T CHO, K OGURA, A ANDO, H TANAKA, M NAKAMURA, S NAKAO, T SHIMOZUMA, S KUBO, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   26 ( 3 )   349 - 359   1986年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/26/3/008

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  • FORMATION OF HIGH-ENERGY ELECTRON TAIL DURING RF PLASMA CURRENT START-UP IN THE WT-2 TOKAMAK 査読

    K OGURA, T CHO, A ANDO, H TANAKA, M IIDA, S IDE, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   55 ( 1 )   13 - 16   1986年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOCIETY JAPAN  

    DOI: 10.1143/JPSJ.55.13

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  • ENHANCEMENT OF EFFICIENCY FOR LOWER HYBRID CURRENT DRIVE BY ELECTRON-CYCLOTRON HEATING IN THE WT-2 TOKAMAK 査読

    A ANDO, K OGURA, H TANAKA, M IIDA, S IDE, M NAKAMURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    NUCLEAR FUSION   26 ( 1 )   107 - 111   1986年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT ATOMIC ENERGY AGENCY  

    DOI: 10.1088/0029-5515/26/1/010

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  • Plasma current generation and sustainment by electron cyclotron waves in the WT-2 Tokamak 査読

    A. Ando, K. Ogura, H. Tanaka, M. Iida, S. Ide, K. Oho, S. Ozaki, M. Nakamura, T. Cho, T. Maekawa, Y. Terumichi, S. Tanaka

    Physical Review Letters   56 ( 20 )   2180 - 2183   1986年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    By injection of microwave power PEC near the electron cyclotron (EC) frequency into an Ohmically heated (OH) plasma in the WT-2 tokamak after OH power is shut off, the plasma current is sustained and ramped up by the EC wave only, without OH power. Here, EC-driven current is generated by EC heating of the suprathermal electron beam in OH plasma. Further, when PEC is injected into plasma sustained by lower-hybrid- (LH-) driven current, the plasma current and its rampup rate increase. Here, EC-driven current is generated by EC heating of the mildly relativistic electrons in LH-driven plasma. © 1986 The American Physical Society.

    DOI: 10.1103/PhysRevLett.56.2180

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  • Electron Cyclotron and Lower Hybrid Current Drive experiments in the WT-2 and WT-3 Tokamaks 査読

    S.Tanaka, Y.Terumichi, T.Maekawa, M.Nakamura, T.Cho, A.Ando, K.Ogura, H.Tanaka, M.Iida, S.Ide,K.Oho, S.Ozaki, R.Itatani, H.Abe, Y.Yasaka, M.Fukao, K.Ishii, A.Mohri, S.Kubo

    Proc. of the 11th International Conference on Plasma Physics and Controlled Nuclear Fusion Research   1   553   1986年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Preliminary experiment on electron beam injection for tokamak current drive 査読

    Hitoshi Tanaka, Akira Ando, Kazuo Ogura, Takashi Maekawa, Yasushi Terumichi, Shigetoshi Tanaka, Akihiro Mohri, Shin Kubo, Mitsuru Hasegawa, Kazumichi Narihara

    Japanese Journal of Applied Physics   24 ( 8 )   644 - 646   1985年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1143/JJAP.24.L644

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  • Study of Low Frequency Density Fluctuations in the WT-2 Tokamak by mm and Submm Wave Scattering 査読

    Y.Terumichi, S.Kubo, A.Ando, Y.Yanagimoto, K.Ogura, H.Tanaka, J.Takahashi, I.Tonai, M.Nakamura, T.Maekawa, S.Tanaka, T.Idehara

    Proc. of the Ninth International Conference on Infrared and Millimeter Waves   Th-8-5   1984年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Current Sustainment by Lower Hybrid Waves in the WT-2 Tokamak 査読

    Masahiko Nakamura, Teruji Cho, Shin Kubo, Takashi Shimozuma, Akira Ando, Kazuo Ogura, Takashi Maekawa, Yasushi Terumichi, Shigetoshi Tanaka

    Journal of the Physical Society of Japan   53 ( 10 )   3399 - 3407   1984年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    When RF power PLHH near the lower hybrid frequency is injected into the ohmically heated plasma in the WT-2 tokamak, the RF-driven current is generated (Irf~-12 kA) and the plasma (ne~-3 x 1012 cm-3)is sustained by this current without ohmic current during the injection of PLhh- The efficiency ofRF current drive is obtained as ITf=0.06PWH/ne R (kA, kW, 1013 cm-3, m),where R is the major radius. The current 7rf is carried by suprathermal electrons which interact resonantly with lower hybrid waves. A high frequency instability and associated relaxation oscillation are observed, which can be suppressed by a simultaneous injection of the electron cyclotron heating power. © 1984, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI: 10.1143/JPSJ.53.3399

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  • Plasma Current Start-Up and Sustainment by RF(Lower Hybrid and Cyclotron) Waves in WT-2 Tokamak 査読

    S.Tanaka, Y.Terumichi, T.Maekawa, M.Nakamura, T.Cho, S.Kubo, T.Shimozuma, A.Ando, K.Ogura, H.Tanaka, J.Takahashi, I.Tonai, Y.Yanagimoto

    Proc. of Tenth International Conference on Plasma Physics and Controlled Nuclear Fusion Research   1   623   1984年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Toroidal Plasma Current Start-Up and Sustainment by rf in the WT-2 Toroidal Device 査読

    Shin Kubo, Teruji Cho, Masahiko Nakamura, Shuji Nakao, Takashi Shimozuma, Akira Ando, Kazuo Ogura, Takashi Maekawa, Yasushi Terumichi, Shigetoshi Tanaka

    Journal of the Physical Society of Japan   53 ( 3 )   1047 - 1057   1984年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    When rf power in the range of lower hybrid frequency was injected into the microwave discharge plasma at the electron cyclotron resonance in the WT-2 toroidal device, the toroidal plasma current is generated, started up to Ip~5KA, and sustained by rf power alone, without the Ohmic heating power (so-called rf tokamak). This lower-hybrid-wave driven current is produced only when high-energy tail electrons, which interact resonantly with the lower hybrid wave, are present in the initial electron cyclotron resonance plasma. © 1984, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI: 10.1143/JPSJ.53.1047

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  • Toroidal Plasma Current Start-up and Sustainment by RF in the WT-2 Tokamak 査読

    S.Tanaka, S.Kubo, M.Nakamura, T.Cho, S.Nakao, T.Shimozuma, A.Ando, K.Ogura, T.Maekawa, Y.Terumichi

    Proc. of the IAEA Technical Committee Meeting on Non-Inductive Current Drive in Tokamaks   327 - 335   1983年

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  • Suppression of hf instability due to rf-driven current by applying ech in the wt-2 tokamak 査読

    T. Maekawa, T. Cho, M. Nakamura, S. Nakao, S. Kubo, T. Shimozuma, A. Ando, K. Ogura, Y. Terumichi, S. Tanaka

    Nuclear Fusion   23 ( 2 )   242 - 246   1983年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    By application of electron cyclotron heating (ECH) to the WT-2 tokamak, the high-frequency instability (relaxation oscillation) excited by the lower-hybrid-wave-driven current is suppressed and the loop voltage decreases without voltage spikes, implying that the driven current increases. This suppression can be ascribed to the isotropization of the current-carrying beam electrons by ECH. © 1983 IOP Publishing Ltd.

    DOI: 10.1088/0029-5515/23/2/012

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  • Plasma Current Start-Up by RF only(EC&LH) on WT-2 査読

    Y.Terumichi, A.Ando, K.Ogura, K.Inoue, H.Tanaka, T.Shimozuma, S.Kubo, S.Nakao, T.Cho, M.Nakamura, T.Maekawa, S.Tanaka

    Proc. of the Fifth Topical Conference on Radio Frequency Plasma Heating   330   1983年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • SCコイルを用いた70GHzジャイロトロンの試作 査読

    佐藤信之, 印牧知広, 出原敏孝, 八木寿郎, 安藤 晃, 小椋一夫, 曄道 恭, 田中茂利, 永田正之, 杉森欣三, 藤田勝利

    核融合研究   49 ( 2 )   133   1983年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1585/jspf1958.49.133

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  • PARTICLE LOSS FROM AN ELECTRON-CYCLOTRON RESONANCE DISCHARGE PLASMA IN THE WT-2 DEVICE 査読

    S NAKAO, K OGURA, Y TERUMICHI, S TANAKA

    PHYSICS LETTERS A   96 ( 8 )   405 - 408   1983年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

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  • TOROIDAL PLASMA CURRENT STARTUP AND SUSTAINMENT BY RF IN THE WT-2 TOKAMAK 査読

    S KUBO, M NAKAMURA, T CHO, S NAKAO, T SHIMOZUMA, A ANDO, K OGURA, T MAEKAWA, Y TERUMICHI, S TANAKA

    PHYSICAL REVIEW LETTERS   50 ( 25 )   1994 - 1997   1983年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

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  • Electron Cyclotron Heating and Preionization in the WT-2 Tokamak 査読

    S.Tanaka, T.Cho, M.Nakamura, S.Nakao, S.Kubo, T.Shimozuma, H.Kawai, K.Yamazaki, A.Ando, K.Ogura, T.Maekawa, Y.Terumichi

    Proc. of the International Conference on Plasma Physics   14a6   84   1982年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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MISC

  • 電子ビームを用いたミリ波・テラヘルツ波発生の基礎と物理 招待

    小椋一夫, 江偉華, 浅川誠, 小方厚, 菅晃一

    プラズマ・核融合学会誌   88 ( 10 )   584   2012年10月

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    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  • 30aC16P 表面波と電子ビームの相互作用の線形解析(加熱・加速)

    渡邉 理, 渡邉 二太, 小椋 一夫, 今井 剛, 長 照二

    プラズマ・核融合学会年会予稿集   ( 22 )   149 - 149   2005年

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    記述言語:日本語   出版者・発行元:プラズマ・核融合学会  

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  • プラズマ利用ミリ波・サブミリ波帯パルス電磁波放射入門

    小椋一夫, 湯上登, 鎌田啓一, 東口武史

    プラズマ・核融合学会誌   79 ( 2 )   164 - 171   2003年12月

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    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:プラズマ・核融合学会  

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  • X-Ray Tomography and Potential Studies in GAMMA 10

    T. Cho, M. Hirata, E. Takahashi, N. Yamaguchi, K. Koganezawa, K. Masai, K. Ogura, T. Kondo, K. Ishii, A. Itakura, T. Saito, A. Mase, Y. Kiwamoto, K. Yatsu, S. Miyoshi

    350 - 351   1990年

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  • 29p-TE-7 LHCD時のSawtooth OscillationとSuppression(プラズマ物理・核融合(WT-III他))

    花田 和明, 小椋 一夫, 吉田 光宏, 榊原 久芳, 南 貴司, 伊藤 岳彦, 岩政 幹人, 井手 俊介, 飯田 素身, 田中 仁, 中村 正彦, 前川 孝, 曄道 恭, 田中 茂利, WT-3グループ

    年会講演予稿集   44 ( 4 )   153 - 153   1989年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 29p-TE-2 WT-IIIのECHとMHD振動(プラズマ物理・核融合(WT-III他))

    田中 仁, 榊原 久芳, 南 貴司, 吉田 光宏, 伊藤 岳彦, 岩政 幹人, 花田 和明, 井手 俊介, 飯田 素身, 小椋 一夫, 安藤 晃, 中村 正彦, 前川 孝, 曄道 恭, 田中 茂利, WT-IIIグループ

    年会講演予稿集   44 ( 4 )   150 - 150   1989年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 29p-TE-4 双方向LHCDによる高βpプラズマの生成(プラズマ物理・核融合(WT-III他))

    前川 孝, 榊原 久芳, 南 貴司, 吉田 光宏, 伊藤 岳彦, 岩政 幹人, 花田 和明, 井手 俊介, 飯田 素身, 田中 仁, 小椋 一夫, 中村 正彦, 曄道 恭, 田中 茂利, WT-3グループ

    年会講演予稿集   44 ( 4 )   151 - 151   1989年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 29p-TE-5 LHW&ECW複合電流駆動時の高速電子の振舞い(プラズマ物理・核融合(WT-III他))

    井手 俊介, 榊原 久芳, 南 貴司, 吉田 光宏, 伊藤 岳彦, 岩政 幹人, 花田 和明, 飯田 素身, 田中 仁, 小椋 一夫, 中村 正彦, 前川 孝, 曄道 恭, 田中 茂利, WT-3グループ

    年会講演予稿集   44 ( 4 )   152 - 152   1989年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 29p-TE-9 WT-3トカマクの周辺プラズマ(プラズマ物理・核融合(WT-III他))

    中村 正彦, 吉田 光宏, 榊原 久芳, 南 貴司, 伊藤 岳彦, 岩政 幹人, 花田 和明, 井手 俊介, 飯田 素身, 田中 仁, 小椋 一夫, 前川 孝, 曄道 恭, 田中 茂利, 澤田 圭司, 末満 英俊, 平田 洋介, 深尾 正之

    年会講演予稿集   44 ( 4 )   154 - 154   1989年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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講演・口頭発表等

  • Non-axisymmetric Radiation from Surface Wave Oscillator Driven by Weakly Relativistic Electron Beam 国際会議

    Yuta Annaka, Kazuo Ogura, Kosuke Ozawa, Makoto Nakasone, Yuki Sato

    12th International Conference on Open Magnetic Systems for Plasma Confinement  2018年8月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Tsukuba, Japan  

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  • Study of Spoof Plasmon Formed on Periodically Corrugated Metal Surface Based on Cavity Resonance Method 国際会議

    Kazuo Ogura, Kei Sekine, Yuta Annaka, Min, Thu San

    12th International Conference on Open Magnetic Systems for Plasma Confinement  2018年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Spoof Plasmon on Periodically Corrugated Metal Cylinder 国際会議

    Min Thu San, Kazuo Ogura, Kei Sekine, Yuta Annaka, Akira Sugawara, Kiyoyuki Yambe, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    The 26th International Toki Conference and The 11th Asia Plasma and Fusion Association Conference  2017年12月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Terahertz Wave Generation Based on Surface Wave Resonator 国際会議

    Kazuo Ogura, Yuta Annaka, Kazuma Iwato, Kiyoyuki Yambe, Teruo Saito

    The 6th International Workshop on Far-Infrared Technologies and The 2nd International Symposium on Development of High Power Terahertz Science and Technology  2017年3月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Fukui, Japan  

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  • Study on Intense Sub-Terahertz Radiation by Oversized Surface Wave Oscillator 国際会議

    Min Thu San, Kazuo Ogura, Kiyoyuki Yambe, Yuta Annaka, Shaoyan Gong

    The 18th International Congress on Plasma Physics  2016年6月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Kaohsiung, Taiwan  

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  • “Experimental Study on Slow Cyclotron Interaction under Anomalous Doppler Effect in W-Band Backward Wave Oscillator 国際会議

    Yuta Annaka, Kazuo Ogura, June Kawamura, Takuro Miura, Takuro Kawamura, Sho Takanashi

    The 25nd International Toki Conference  2015年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Experimental Study on W-band Oversized Surface Wave Oscillator Driven by Weakly Relativistic Electron Beam 国際会議

    Min Thu San, Kazuo Ogura, Kiyoyuki Yambe, Yuta Annaka, Shaoyan Gong, Jun Kawamura, Takuro Miura, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    The 25nd International Toki Conference  2015年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Oscillation Starting Condition for Oversized G-Band Backward Wave Oscillator Driven by a Weakly Relativistic Electron Beam 国際会議

    Shaoyan Gong, Kazuo Ogura, Shintaro Nomizu, Kosuke Yamazaki, Kiyoyuki Yambe, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    The 5th Euro-Asian Pulsed Power Conference  2014年9月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Kumamoto, Japan  

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  • Beam Interactions with Surface Waves and Higher Order Modes in Oversized G-band Slow-Wave Structure 国際会議

    Kazuo Ogura, Akihiro Shirai, Masahiko Ogata, Kiyoyuki Yambe

    The 5th Euro-Asian Pulsed Power Conference  2014年9月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Kumamoto, Japan  

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  • Enhancement of Smith-Purcell Radiations by Self-Bunched Electron Beams in Oversized Backward Wave Oscillator 国際会議

    Kazuo Ogura, Kiyoyuki Yambe, Takayuki Iwasaki, Shota Magori, Junpei Kojima

    The 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams  2014年5月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Washington, DC, USA  

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  • Surface Waves in Oversized G-Band Slow-Wave Structures with Rectangular Corrugations 国際会議

    Kazuo Ogura, Akihiko Kojima, Fumiaki Kawabe, Kiyoyuki Yambe, Md. Ruhul Amin

    23nd International Toki Conference  2013年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Experimental Study on G-band Oversized Backward Wave Oscillator Driven by Weakly Relativistic Electron Beam 国際会議

    Shota Magori, Kazuo Ogura, Takayuki Iwasaki, Junpei Kojima, Kiyoyuki Yambe, Shin Kubo, Takashi Shimozuma, Sakuji Kobayashi, Kohji Okada

    23nd International Toki Conference  2013年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Beam Interactions with Surface Waves and Higher Order Modes in Oversized Backward Wave Oscillators 国際会議

    Kazuo Ogura, Akihiko Kojima, Fumiaki Kawabe, Kiyoyuki Yambe

    9th Asia Plasma and Fusion Association Conference  2013年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Gyeongju, Korea  

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  • Experimental Study on Smith-Purcell Radiations of Weakly Relativistic Oversized Backward Wave Oscillators 国際会議

    Takayuki Iwasaki, Kazuo Ogura, Shota Magori, Junpei Kojima, Kiyoyuki Yambe

    9th Asia Plasma and Fusion Association Conference  2013年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Gyeongju, Korea  

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  • Higher Order Mode Radiations of Weakly Relativistic Oversized Backward Wave Oscillator 国際会議

    K. Ogura, K. Yambe, S. Hasegawa, T. Iwasaki, K. Yamamoto, Y. Kobari

    22nd International Toki Conference  2012年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Normal Modes and Slow-Wave Instabilities in Oversized Coaxial Slow-Wave Structure with Rectangular Corrugations 国際会議

    Kazuo Ogura, Kiyoyuki Yambe, Kazumasa Yamamoto, Yoshihiro Kobari

    4th Euro-Asian Pulsed Power Conference and 19th International Conference on High-Power Beams  2012年9月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Karlsruhe, Germany  

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  • Experimental Study on Generation of Electron Beam Utilizing Cold Cathode in the Weakly Relativistic Energy Region 国際会議

    Kiyoyuki Yambe, Kazuo Ogura, Shinji Hasegawa, Takaki Shinada, Takayuki Iwasaki, Tsubasa Furuichi

    4th Euro-Asian Pulsed Power Conference and 19th International Conference on High-Power Beams  2012年9月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Karlsruhe, Germany  

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  • Smith-Purcell Radiation Based on Cylindrical Surface Waves 国際会議

    S. Hasegawa, K. Ogura, T. Iwasaki, K. Yambe

    oint conference of 9th International Conference on Open Magnetic Systems for Plasma Confinement and 3rd International Workshop on Plasma Material Interaction Facilities for Fusion  2012年8月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Tsukuba, Japan  

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  • Normal Modes and Slow-Wave Instabilities in Oversized Coaxial Slow-Wave Structure with Rectangular Corrugations 国際会議

    Kazuo Ogura, Kiyoyuki Yambe, Kazumasa Yamamoto, Yoshihiro Kobari

    Joint conference of 9th International Conference on Open Magnetic Systems for Plasma Confinement and 3rd International Workshop on Plasma Material Interaction Facilities for Fusion  2012年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Tsukuba, Japan  

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  • Cylindrical Surface Wave on Periodically Corrugated Metal Cylinder 国際会議

    H. Iiduka, K. Ogura, K. Yambe

    21st International Toki Conference on Integration of Fusion Science and Technology for Steady State Operation  2011年11月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Toki, Japan  

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  • Numerical Study of Slow-Wave Instabilities in Oversized Coaxial Slow-Wave Structure 国際会議

    K. Ogura, S. Abe, H. Kimura, K. Yamamoto, K. Yambe, Md. R. Amin

    3rd Euro-Asian Pulsed Power Conference and 18th International Conference on High-Power Beams  2010年10月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Jeju Island, Korea  

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  • Experimental Study on Weakly Relativistic Oversized Backward Wave Oscillator with Coaxial Rectangular Corrugations 国際会議

    M. Takahashi, K. Ogura, H. Yoshimura, H. Iiduka, A. Sugawara, K. Yambe, W. S. Kim

    3rd Euro-Asian Pulsed Power Conference and 18th International Conference on High-Power Beams  2010年10月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:Jeju Island, Korea  

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▶ 全件表示

受賞

  • The Sir Thomas Ward Memorial Medal

    2000年1月   The Institute of Engineer (India)  

    Md. R. Amin, Md. A. Goffar Khan, K. Ogura

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    受賞区分:学会誌・学術雑誌による顕彰  受賞国:インド

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共同研究・競争的資金等の研究

  • 2重コルゲート遅波構造を用いた広帯域パルス表面波発振器の研究

    2011年11月 - 2014年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    小椋 一夫

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    担当区分:研究代表者  資金種別:競争的資金

    配分額:13300000円 ( 直接経費:9310000円 、 間接経費:3990000円 )

    2重コルゲート遅波構造を用いた広帯域パルス表面波発振器の研究を行った。20-40GHz帯のコルゲート表面波の分散特性を数値解析と実験により調べた。2重コルゲート遅波構造を励起するための100kV以下の弱い相対論的電子ビームは熱陰極ではなく,ディスク型冷陰極を用いて生成した。大強度表面波励起により2割程度の広帯域動作を実現した。また数値解析により2重コルゲートの高次モードによる高周波化の可能性を調べ,実験により比較的大強度の高次モード動作が確認された。さらに表面波の周波数を170GHz帯まで拡張して大強度励起を実証した。大強度表面波励起をテラヘルツ帯へ展開する上で重要な研究成果である。

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  • 異常ドップラー効果による表面波励起を用いた弱い相対論的大電力遅波ミリ波源の研究

    2005年4月 - 2008年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    資金種別:競争的資金

    配分額:14800000円 ( 直接経費:14560000円 、 間接経費:240000円 )

    本研究では弱い相対論的電子ビームによりオーバーサイズ遅波導波管の表面波を励起することを目指した。まず,弱い相対論的領域では大電流の電子ビーム生成そのものも解決すべき重要な問題である。新しくディスクタイプの冷陰極を提案し,弱い相対論的領域で均一性の良いビームを発生させることができた。ビーム回収ポートについては,今後さらに検討する必要がある。
    電子ビームとオーバーサイズ遅波導波管特性の改善により20GHz帯で約500kW,40GHz帯で約200kWまで出力が上昇した。また,軸対称モードと非軸対称モードの制御が可能であることを実証した。遅波構造として矩形を採用して平坦なアッパーカットオフを実現し,比較的エネルギーの低い領域でチェレンコフ相互作用と遅波サイクロトロン相互作用が共鳴した異常ドップラー効果による表面波励起を行った。低磁場と低エネルギー領域での表面波励起とモード制御の成果であり,将来性の見込める成果といえる。
    オー

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  • 異常ドップラー効果による遅波サイクロトロンメーザの研究

    2000年4月 - 2003年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

      詳細を見る

    資金種別:競争的資金

    配分額:14600000円 ( 直接経費:14600000円 )

    本研究では,異常ドップラー効果による遅波サイクロトロン共鳴相互作用の誘導放射を利用し単一スペクトルの電磁波を得る遅波サイクロトロンメーザを提案した。研究成果の概要を箇条書きにまとめる。
    ・磁場システム製作と電子ビーム制御
    磁場配意が可変な磁場システムを新たに構築した。磁場コイルの電流分布と磁場配位の関係を定量的に調べ,軸方向414mm,半径方向60mmの範囲で変化率5%以内の磁場が得られた。この磁場による制御により,高真空状態において,60kV程度,数100Aの電子ビームを360mm以上伝搬させることができた。
    ・異常ドップラー効果による遅波サイクロトロンメーザの研究
    遅波サイクロトロンメーザ動作の理論的解析結果は,米国の雑誌Phys. Rev. Eに論文として掲載された。また,K-Band大口径波形導波管により,チェレンコフ相互作用と遅波サイクロトロン相互作用によるマイクロ波発生について調べた。発振周波数は20-25GHz,発振電力は最大で約100kW(約2%)が

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担当経験のある授業科目(researchmap)

  • 電気電子工学コースセミナーⅠ

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

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  • 電気電子工学セミナーⅠ

    機関名:新潟大学

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  • 電気電子工学特定研究Ⅱ

    機関名:新潟大学

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  • 電気電子工学特定研究Ⅰ

    機関名:新潟大学

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  • 技術英語入門

    機関名:新潟大学

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  • 電気電子工学研究発表演習(中間発表)

    機関名:新潟大学

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  • 電気電子工学文献詳読Ⅱ

    機関名:新潟大学

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  • 電気電子工学文献詳読Ⅰ

    機関名:新潟大学

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  • 電気電子工学セミナーⅡ

    機関名:新潟大学

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  • 電気電子工学コース演習

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • 電気電子創造設計

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • 電気磁気エネルギー工学

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

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  • 総合工学概論

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 卒業研究

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

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  • 電気電子工学実験IV

    機関名:新潟大学

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  • 電気電子創造設計

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 総合技術科学演習

    機関名:新潟大学

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  • 総合技術科学演習

    機関名:新潟大学

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  • 電気情報工学特定研究Ⅰ

    機関名:新潟大学

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  • 卒業研究

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 論文輪講

    機関名:新潟大学

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  • 総合工学概論

    機関名:新潟大学

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  • 物理工学特論1

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • 総合技術科学演習

    機関名:新潟大学

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  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • 電気電子設計製図

    機関名:新潟大学

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  • 総合技術科学演習

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 電気電子工学実験IV

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 外国語論文解説・討論Ⅰ

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 電気磁気エネルギー工学

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 電気電子設計製図

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • 外国語論文解説・討論Ⅰ

    機関名:新潟大学

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  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

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  • 電気情報工学博士セミナーⅠ

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

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  • 電気電子工学文献詳読Ⅰ

    機関名:新潟大学

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  • 電気磁気エネルギー工学

    機関名:新潟大学

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  • 電気情報工学特定研究Ⅰ

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 電気電子工学研究発表(外部発表)

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 電気電子工学研究発表演習(中間発表)

    機関名:新潟大学

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  • 電気電子演習

    機関名:新潟大学

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  • 電気電子工学文献詳読Ⅱ

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 卒業研修

    機関名:新潟大学

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  • 電気電子創造設計

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

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  • 電磁気学演習I

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 電気電子工学実験III

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

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  • 電気電子工学実験IV

    機関名:新潟大学

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  • 電気電子創造設計

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

     詳細を見る

  • 論文輪講

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験I

    機関名:新潟大学

     詳細を見る

  • 電気電子設計製図

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

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  • 電気電子設計製図

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験IV

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

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  • プラズマ応用工学

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 電気電子工学コース演習

    機関名:新潟大学

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  • 電気電子工学実験IV

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 物理工学II

    機関名:新潟大学

     詳細を見る

  • 卒業研修

    機関名:新潟大学

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  • エレクトロニクスへの招待

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

     詳細を見る

  • スタディスキルズ(電気電子工学)

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験II

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

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  • 論文輪講

    機関名:新潟大学

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  • 物理工学III

    機関名:新潟大学

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  • 物理工学III

    機関名:新潟大学

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  • 電気電子演習

    機関名:新潟大学

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  • 電気電子工学実験II

    機関名:新潟大学

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  • 電気電子工学実験IV

    機関名:新潟大学

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  • 物理工学IV

    機関名:新潟大学

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  • 高電圧工学

    機関名:新潟大学

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  • 物理工学II

    機関名:新潟大学

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  • 卒業基礎研究

    機関名:新潟大学

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  • 電気電子工学実験I

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験III

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

     詳細を見る

  • 論文輪講

    機関名:新潟大学

     詳細を見る

  • 電気電子工学特定研究Ⅱ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験I

    機関名:新潟大学

     詳細を見る

  • 電気電子工学特定研究Ⅰ

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • エレクトロニクスへの招待

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験II

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験III

    機関名:新潟大学

     詳細を見る

  • 電磁気学演習I

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験III

    機関名:新潟大学

     詳細を見る

  • 電気電子工学セミナーⅡ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験IV

    機関名:新潟大学

     詳細を見る

  • 電気電子工学セミナーⅠ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験III

    機関名:新潟大学

     詳細を見る

  • プラズマ応用工学

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

     詳細を見る

  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

     詳細を見る

  • 物理工学II

    機関名:新潟大学

     詳細を見る

  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験IV

    機関名:新潟大学

     詳細を見る

  • 物理工学II

    機関名:新潟大学

     詳細を見る

  • 卒業基礎研究

    機関名:新潟大学

     詳細を見る

  • 中間発表

    機関名:新潟大学

     詳細を見る

  • 外国語論文解説・討論Ⅱ

    機関名:新潟大学

     詳細を見る

  • 電気情報工学特定研究Ⅱ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学研究発表演習(外部発表)

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験II

    機関名:新潟大学

     詳細を見る

  • 高電圧工学

    機関名:新潟大学

     詳細を見る

  • 物理工学IV

    機関名:新潟大学

     詳細を見る

  • 電気電子工学コースセミナーⅡ

    機関名:新潟大学

     詳細を見る

  • 電気電子創造設計

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験IV

    機関名:新潟大学

     詳細を見る

  • 工学リテラシー入門(電気電子工学科)

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • プラズマ応用工学

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験III

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験I

    機関名:新潟大学

     詳細を見る

  • 物理工学II

    機関名:新潟大学

     詳細を見る

  • エレクトロニクスへの招待

    機関名:新潟大学

     詳細を見る

  • 電気電子設計製図

    機関名:新潟大学

     詳細を見る

  • 論文輪講

    機関名:新潟大学

     詳細を見る

  • エレクトロニクスへの招待

    機関名:新潟大学

     詳細を見る

  • 電気電子工学文献詳読Ⅰ

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • 電気電子工学セミナーⅡ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学セミナーⅠ

    機関名:新潟大学

     詳細を見る

  • 物理工学特論II

    機関名:新潟大学

     詳細を見る

  • プラズマ応用工学

    機関名:新潟大学

     詳細を見る

  • 電気電子工学特定研究Ⅱ

    機関名:新潟大学

     詳細を見る

  • 電気電子工学実験IV

    機関名:新潟大学

     詳細を見る

  • 電気情報工学特定研究Ⅲ

    機関名:新潟大学

     詳細を見る

  • 論文輪講

    機関名:新潟大学

     詳細を見る

  • 電気電子工学研究発表(外部発表)

    機関名:新潟大学

     詳細を見る

  • 物理工学III

    機関名:新潟大学

     詳細を見る

  • 電気電子工学研究発表演習(中間発表)

    機関名:新潟大学

     詳細を見る

  • 物理工学III

    機関名:新潟大学

     詳細を見る

  • 電気電子工学文献詳読Ⅱ

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • 電気電子工学特定研究Ⅰ

    機関名:新潟大学

     詳細を見る

  • 卒業研修

    機関名:新潟大学

     詳細を見る

  • 電気電子演習

    機関名:新潟大学

     詳細を見る

  • 電気磁気エネルギー工学

    機関名:新潟大学

     詳細を見る

  • 卒業研究

    機関名:新潟大学

     詳細を見る

  • プラズマ応用工学

    機関名:新潟大学

     詳細を見る

  • 電気電子設計製図

    機関名:新潟大学

     詳細を見る

  • 電気電子創造設計

    機関名:新潟大学

     詳細を見る

  • 自然科学総論Ⅴ

    機関名:新潟大学

     詳細を見る

▶ 全件表示

担当経験のある授業科目

  • プロジェクト研究特別概説

    2021年
    -
    現在
    機関名:新潟大学

  • 論文輪講I

    2020年
    -
    現在
    機関名:新潟大学

  • 電子情報通信実験IIIB

    2020年
    -
    現在
    機関名:新潟大学

  • 電子情報通信実験IIIA

    2020年
    -
    現在
    機関名:新潟大学

  • 電子情報通信設計製図

    2020年
    -
    現在
    機関名:新潟大学

  • 論文輪講II

    2020年
    -
    現在
    機関名:新潟大学

  • 工学リテラシー入門(情報電子分野)

    2019年
    -
    現在
    機関名:新潟大学

  • 電子情報通信実験IIB

    2019年
    機関名:新潟大学

  • 電子情報通信実験IIA

    2019年
    機関名:新潟大学

  • 科学技術者の倫理

    2019年
    機関名:新潟大学

  • 電子情報通信実験IA

    2018年
    機関名:新潟大学

  • 電子情報通信実験IB

    2018年
    機関名:新潟大学

  • 総合工学概論

    2017年
    -
    現在
    機関名:新潟大学

  • 総合技術科学演習

    2017年
    -
    現在
    機関名:新潟大学

  • 電気情報工学博士セミナーⅠ

    2015年
    機関名:新潟大学

  • 電気電子工学研究発表(外部発表)

    2014年
    -
    2015年
    機関名:新潟大学

  • 電気情報工学特定研究Ⅲ

    2014年
    機関名:新潟大学

  • 電気電子工学特定研究Ⅱ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学文献詳読Ⅰ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学セミナーⅠ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学セミナーⅡ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学特定研究Ⅰ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学文献詳読Ⅱ

    2013年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学研究発表演習(中間発表)

    2013年
    -
    2015年
    機関名:新潟大学

  • 中間発表

    2013年
    機関名:新潟大学

  • 電気電子工学コースセミナーⅡ

    2013年
    機関名:新潟大学

  • 外国語論文解説・討論Ⅱ

    2013年
    機関名:新潟大学

  • 電気情報工学特定研究Ⅱ

    2013年
    機関名:新潟大学

  • 電気電子工学研究発表演習(外部発表)

    2013年
    機関名:新潟大学

  • 技術英語入門

    2013年
    機関名:新潟大学

  • 電気電子工学コース演習

    2012年
    -
    2015年
    機関名:新潟大学

  • 外国語論文解説・討論Ⅰ

    2012年
    -
    2015年
    機関名:新潟大学

  • 電気情報工学特定研究Ⅰ

    2012年
    -
    2015年
    機関名:新潟大学

  • 電気電子工学コースセミナーⅠ

    2012年
    機関名:新潟大学

  • 物理工学特論1

    2011年
    機関名:新潟大学

  • 電気電子設計製図

    2010年
    -
    2018年
    機関名:新潟大学

  • 電気電子創造設計

    2010年
    -
    2016年
    機関名:新潟大学

  • 卒業研修

    2009年
    -
    現在
    機関名:新潟大学

  • 工学リテラシー入門(電気電子工学科)

    2009年
    -
    2016年
    機関名:新潟大学

  • 電磁気学演習I

    2009年
    -
    2010年
    機関名:新潟大学

  • 自然科学総論Ⅴ

    2008年
    機関名:新潟大学

  • スタディスキルズ(電気電子工学)

    2008年
    機関名:新潟大学

  • 高電圧工学

    2007年
    -
    現在
    機関名:新潟大学

  • 物理工学IV

    2007年
    -
    現在
    機関名:新潟大学

  • プラズマ応用工学

    2007年
    -
    現在
    機関名:新潟大学

  • 卒業研究

    2007年
    -
    現在
    機関名:新潟大学

  • 論文輪講

    2007年
    -
    2019年
    機関名:新潟大学

  • 電気電子工学実験IV

    2007年
    -
    2018年
    機関名:新潟大学

  • 物理工学II

    2007年
    -
    2018年
    機関名:新潟大学

  • 電気電子工学実験III

    2007年
    -
    2018年
    機関名:新潟大学

  • 電気電子工学実験I

    2007年
    -
    2017年
    機関名:新潟大学

  • 電気電子工学実験II

    2007年
    -
    2017年
    機関名:新潟大学

  • エレクトロニクスへの招待

    2007年
    -
    2016年
    機関名:新潟大学

  • 電気磁気エネルギー工学

    2007年
    -
    2016年
    機関名:新潟大学

  • 電気電子演習

    2007年
    -
    2009年
    機関名:新潟大学

  • 物理工学III

    2007年
    -
    2008年
    機関名:新潟大学

  • 卒業基礎研究

    2007年
    -
    2008年
    機関名:新潟大学

  • 物理工学特論II

    2007年
    機関名:新潟大学

▶ 全件表示