Recent R&D activities of negative-ion-based ion source for JT-60SA Yoshitaka Ikeda; Masaya Hanada; Masaki Kamada; Kaoru Kobayashi; Naotaka Umeda; Noboru Akino; Noboru Ebisawa; Takashi Inoue; Atsushi Honda; Mikito Kawai; Minoru Kazawa; Katsumi Kikuchi; Masao Komata; Kazuhiko Mogaki; Katsuya Noto; Kuzumi Oasa; Katsumi Oshima; Shunichi Sasaki; Tatsuya Simizu; Tadashi Takenouchi; Yutaka Tanai; Katsutomi Usui; Kazuhiro Watanabe; Larry R. Grisham; Shinichi Kobayashi; Yasushi Yamano; Masahiro Takahashi
巻：36,
号：4,
開始ページ：1519,
終了ページ：1529, 2008年08月
The JT-60 Super Advanced (JT-60SA) tokamak aims to perform the ITER support and to demonstrate steady-state high-beta plasma project with the collaboration between Japan and EU. To attain these objectives, the negative-ion-based NBI (N-NBI) system is required to inject 10 MW for 100 s at the beam energy of 500 keV. On JT-60U, the present N-NBI ion source has injected 3.2 MW for 21 s at 320 keV; however, three key issues should be solved for the JT-60SA N-NBI ion source. One is to improve the voltage holding capability of the large negative ion source, where the available acceleration voltage has been limited to less than similar to 400 kV due to breakdowns. The accelerator of the JT-60U ion source is composed of large three-stage grids and three fiberglass reinforced plastic (FRP) insulators. Recent R&D tests suggested that the FRP insulators were not the main factor to trigger the breakdowns at the early conditioning stage. The accelerator with a large area of grids and their supporting structure may need a high margin in the design of electric field and a long time for conditioning. The second issue is to reduce the power loading of the acceleration grids. It was found that some beamlets were strongly deflected due to beamlet-beamlet interaction and strike on the grounded grid in the accelerator. Moreover, the electrons generated in the accelerator caused the grid loading and the overheating of the beamline components. The acceleration grids for JT-60SA are to be designed by taking account of the beamlet-beamlet interaction and the applied magnetic field in 3-D simulation. Third is to maintain the D- production for 100 s. Although a constant D- beam power was confirmed on JT-60U for 21 s, an active cooling system is required to keep the temperature of the plasma grid (PG) under optimum condition during 100-s operation. A simple cooling structure is proposed for the active cooled PG, where a key is the temperature gradient on the PG for uniform D- production. In the present schedule, design work, reflecting the latest R&D progress, will continue until similar to 2011. The modified N-NBI ion source will start on JT-60SA in 2015.
英語
DOI：https://doi.org/10.1109/TPS.2008.927382DOI ID：10.1109/TPS.2008.927382,
ISSN：0093-3813,
Web of Science ID：WOS:000258618300011 Microplasma discharge in ethanol solution: Characterization and its application to the synthesis of carbon microstructures Qiang Chen; Takaya Kitamura; Kenji Saito; Koji Haruta; Yasushi Yamano; Tatsuo Ishikawa; Hajime Shirai
巻：516,
号：13,
開始ページ：4435,
終了ページ：4440, 2008年05月
Radio-frequency (rf) microplasma discharge of argon was successfully generated within an ethanol (EtOH) solution and applied for the synthesis of carbon microstructures. The plasma state depends on the flow rate of argon as well as the EtOH concentration. The argon related species are consumed mostly for dissociating EtOH at concentration of over 10%. The carbon related microstructures such as particle and nanotubes (CNTs) were formed directly on c-Si utilizing a microplasma jet of argon generated within ethanol solution, the average size and number density of carbon related products could be controlled by adjusting the ethanol concentration. The determining factor of average size and number density of carbon microstructures are discussed in terms of the surface reaction within ethanol solution. (c) 2007 Elsevier B.V. All rights reserved.
英語
DOI：https://doi.org/10.1016/j.tsf.2007.10.052DOI ID：10.1016/j.tsf.2007.10.052,
ISSN：0040-6090,
Web of Science ID：WOS:000255584800013 Surface discharge related properties of fiberglass reinforced plastic insulator for use in neutral beam injector of JT-60U Y. Yamano; M. Takahashi; S. Kobayashi; M. Hanada; Y. Ikeda
巻：79,
号：2,
開始ページ：02A524-1-02A524-4, 2008年02月
Neutral beam injection (NBI) used for JT-60U is required to generate negative ions of 500 keV energies. To produce such high-energy ions, three-stage electrostatic accelerators consisting of three insulator rings made of fiberglass reinforced plastic (FRP) are applied. The surface discharges along FRP insulators are one of the most serious problems in the development of NBI. To increase the hold-off voltage against surface flashover events, it is necessary to investigate the FRP insulator properties related to surface discharges in vacuum. This paper describes surface flashover characteristics for FRP and alumina samples under vacuum condition. The results show that the fold-off voltages for FRP samples are inferior to those of alumina ceramics. In addition, measurement results of surface resistivity and volume resistivity under vacuum and atmospheric conditions, secondary electron emission characteristics, and cathodoluminescence under some keV electron beam irradiation are also reported. These are important parameters to analyze surface discharge of insulators in vacuum. (C) 2008 American Institute of Physics.
英語
DOI：https://doi.org/10.1063/1.2828069DOI ID：10.1063/1.2828069,
ISSN：0034-6748,
Web of Science ID：WOS:000254194800056 特殊極限環境下における各種絶縁体の電気伝導および帯電特性評価
山納康
総合研究機構研究プロジェクト研究成果報告書, 号：6(平成19年度), 2008年
In-situ帯電計測装置を備えた絶縁体からの二次電子電流測定システムの開発
山納康
総合研究機構研究プロジェクト研究成果報告書, 号：6(平成19年度), 2008年
特殊極限環境下における各種絶縁体の電気伝導および帯電特性評価
山納康
号：6(平成19年度), 2008年
In-situ帯電計測装置を備えた絶縁体からの二次電子電流測定システムの開発
山納康
号：6(平成19年度), 2008年
Vacuum electrical breakdown characteristics and surface condition of Ti electrodes with oxidation conditions Y Ito; Y Yamano; S Kobayashi; Y Saito
巻：13,
号：1,
開始ページ：98,
終了ページ：104, 2006年02月
Outgassing from an electrode surface is regarded as a major factor leading to electrical breakdowns in vacuum. Recently oxidation treatment at 200 degrees C was reported as an effective means of reducing Ti outgassing. In this paper, we report our measurement and comparison of the electrical breakdown characteristics of Ti electrodes with different oxidation conditions (without oxidation, oxidation at 200 degrees C, oxidation at 450 degrees C). In addition, we analyzed electrode surfaces before and after breakdown experiments in situ with X-ray photoelectron spectroscopy (XPS). Before oxidation, we machined the electrode's surfaces to the roughness of 0.8 mu m Rmax with diamond turning. Breakdown experiments demonstrated that the breakdown field is highest at the first application of voltage to electrodes with oxidized at 200 degrees C. Before breakdown experiment, surface analysis revealed that all the sample electrodes had a large amount of carbon originating from the hydrocarbons of contaminants, and after the experiments, they revealed that the carbons had disappeared. To obtain breakdown characteristics of electrodes with smoother surfaces, we conducted experiments on electrodes with a surface roughness of 0.05 mu m Ra. For these electrodes, the breakdown field was higher at first breakdown; the repetitions required to achieve saturated breakdown fields were significantly fewer, and the amount of carbon on electrode surfaces before breakdown was less.
英語
DOI：https://doi.org/10.1109/TDEI.2006.1593407DOI ID：10.1109/TDEI.2006.1593407,
ISSN：1070-9878,
CiNii Articles ID：120001371240,
Web of Science ID：WOS:000235419200014 Secondary electron emission and surface charging evaluation of alumina ceramics and sapphire Suharyanto; Y Yamano; S Kobayashi; S Michizono; Y Saito
巻：13,
号：1,
開始ページ：72,
終了ページ：78, 2006年02月
The breakdown of alumina rf windows is mostly caused by multipactor, as well as by material defects and contamination. Since multipator induces localized surface heating, leading to surface melting, it is necessary to observe secondary electron emission (SEE) coefficients of alumina ceramics under high temperature conditions. The SEE coefficients of commercial alumina ceramics and sapphire were measured by a scanning electron microscopy (SEM) with a single short-pulsed electron beam (100 pA, 1 ms) at room temperature and at 650 degrees C. Additive materials used for sintering alumina, such as SiO2 and MgO, were also investigated. Surface charging evaluations have also become important because the accumulated charges are discharged at the threshold field, resulting in surface discharge. The surface charging evaluations were carried out by multi-pulse measurements with the injection of successive pulses on the sample. As a result, reductions in the SEE coefficients with temperature were confirmed, except for sapphire. The multi-pulse measurement results indicated that surface charging of the sapphire was higher than that of other samples. This may be one of the factors that causes sapphire not to be durable for rf window applications, compared with alumina ceramics. Although there are few exceptions, it was found that the SEE coefficients of alumina ceramics increased with the purity and the average grain size.
英語
DOI：https://doi.org/10.1109/TDEI.2006.1593403DOI ID：10.1109/TDEI.2006.1593403,
ISSN：1070-9878,
CiNii Articles ID：120001371239,
Web of Science ID：WOS:000235419200010 Influence of mechanical finishing on secondary electron emission of alumina ceramics Suharyanto; S. Michizono; Y. Saito; Tumiran; Y. Yamano; S. Kobayashi
巻：1,
開始ページ：97,
終了ページ：100, 2006年
Secondary electron emission (SEE) coefficients of alumina ceramics with three different surface finishes have been measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). SEE coefficients of those aluminas with annealing process became lower after mechanical grinding operations even though its average roughness was almost same as those of as-sintered ones. SEE coefficients of mirror-finished samples were the smallest among the samples. Changes of SEE coefficient with incident angle of primary electrons for smooth and rough surfaces are also discussed. © 2006 IEEE.
英語
DOI：https://doi.org/10.1109/DEIV.2006.357240DOI ID：10.1109/DEIV.2006.357240,
ISSN：1093-2941,
SCOPUS ID：46649099104 真空中における沿面放電時のリアルタイム帯電分布測定に関する研究<論文>
山納康; 宮内泰寿; 小林信一
埼玉大学紀要, 工学部, 第1部論文集, 巻：1, 号：38, 開始ページ：1, 終了ページ：5, 2005年
高圧半導体保護用エッチングヒューズの開発 (続）
浅山三夫; 石川雄三; 広瀬健吾; 小林信一; 山納康
埼玉大学地域共同研究センター紀要, 号：6, 開始ページ：67, 終了ページ：70, 2005年
We are continuing to develop high voltage etching fuse for protecting semiconductors. Last year fundamental researches to find etching patterns bringing better current breaking capability were conducted, and successfully completed. This year 7.2kV rating etching fuse was developed based on the results of fundamental researches of last year. It was confirmed that this type of etching fuse has good breaking performance and smaller I2t value compared with target value were obtained.Therefore it will be possible to produce a high voltage etching fuse for protecting semiconductors having lower I2t than those of current products.
埼玉大学総合研究機構地域共同研究センター産学連携推進部門, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371340, CiNii Books ID：AA11808968
真空沿面放電時のトリプルジャンクションにおける電子放出箇所の微視的観測
山納康
総合研究機構研究プロジェクト研究成果報告書, 巻：16年度, 2005年
真空中における沿面放電時のリアルタイム帯電分布測定に関する研究<論文>
山納康; 宮内泰寿; 小林信一
巻：1, 号：38, 開始ページ：1, 終了ページ：5, 2005年
高圧半導体保護用エッチングヒューズの開発(続)
浅山 三夫; 石川 雄三; 広瀬 健吾; 小林 信一; 山納 康
埼玉大学地域共同研究センター紀要, 号：6, 開始ページ：67, 終了ページ：70, 2005年
We are continuing to develop high voltage etching fuse for protecting semiconductors. Last year fundamental researches to find etching patterns bringing better current breaking capability were conducted, and successfully completed. This year 7.2kV rating etching fuse was developed based on the results of fundamental researches of last year. It was confirmed that this type of etching fuse has good breaking performance and smaller I2t value compared with target value were obtained.Therefore it will be possible to produce a high voltage etching fuse for protecting semiconductors having lower I2t than those of current products.
埼玉大学総合研究機構地域共同研究センター産学連携推進部門, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371340, CiNii Books ID：AA11808968
真空沿面放電時のトリプルジャンクションにおける電子放出箇所の微視的観測
山納康
巻：16年度, 2005年
Charging characteristics on dielectric surface by different charging processes in vacuum Y Yamano; A Ohashi; K Kato; H Okubo; Y Hakamata
巻：6,
号：4,
開始ページ：464,
終了ページ：468, 1999年08月
This paper describes charging characteristics on a dielectric surface in vacuum by electron irradiation, and field emission by a triple junction under negative and positive de Hv applications. We measured the 2-dimensional distribution of electrostatic charging on a dielectric surface in situ. Experimental results revealed that the negative charge distribution caused by the electron beam had a conical shape over the whole surface. On the other hand, for a triple junction, it was an acute distribution around the triple junction. Moreover, we quantitatively investigated the difference of the 2-dimensional charging distribution, using certain shape parameters, between the two charging processes mentioned above. In addition, we examined the time decay characteristics of the surface potential on the dielectric in vacuum.
英語
DOI：https://doi.org/10.1109/94.788746DOI ID：10.1109/94.788746,
ISSN：1070-9878,
eISSN：1558-4135,
CiNii Articles ID：30020038289,
Web of Science ID：WOS:000082543000016 真空中の電子照射による絶縁物上帯電分布の形成機構
山納康; 大橋敦; 加藤克巳; 袴田好美; 大久保仁
電気学会 論文誌A, 巻：119-A, 号：6, 開始ページ：841, 終了ページ：847, 1999年
真空中の電子照射による絶縁物上帯電分布の形成機構
山納康; 大橋敦; 加藤克巳; 袴田好美; 大久保仁
巻：119-A, 号：6, 開始ページ：841, 終了ページ：847, 1999年
個体ターゲットへのレーザ照射による真空中プラズマの発光形態
山納康; 大橋敦; 加藤克巳; 大久保仁
電気学会 論文誌A, 巻：119-A, 号：6, 開始ページ：878, 終了ページ：883, 1996年
個体ターゲットへのレーザ照射による真空中プラズマの発光形態
山納康; 大橋敦; 加藤克巳; 大久保仁
巻：119-A, 号：6, 開始ページ：878, 終了ページ：883, 1996年
