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ion sourceOguri, Hidetomo; Ueno, Akira; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori
Review of Scientific Instruments, 81(2), p.02A715_1 - 02A715_3, 2010/02
Times Cited Count：3 Percentile：18.27(Instruments & Instrumentation) ion sourceIkegami, Kiyoshi*; Ueno, Akira; Oguri, Hidetomo; Namekawa, Yuya; Okoshi, Kiyonori
Review of Scientific Instruments, 81(2), p.02A717_1 - 02A717_4, 2010/02
Times Cited Count：3 Percentile：18.27(Instruments & Instrumentation) ion source for Japan Proton Accelerator Research Complex upgradeOkoshi, Kiyonori; Namekawa, Yuya; Ueno, Akira; Oguri, Hidetomo; Ikegami, Kiyoshi*
Review of Scientific Instruments, 81(2), p.02A716_1 - 02A716_4, 2010/02
Times Cited Count：6 Percentile：30.96(Instruments & Instrumentation) ion beam acceleration in MeV acceleratorTaniguchi, Masaki; Mizuno, Takatoshi; Umeda, Naotaka; Kashiwagi, Mieko; Watanabe, Kazuhiro; Tobari, Hiroyuki; Kojima, Atsushi; Tanaka, Yutaka; Dairaku, Masayuki; Hanada, Masaya; et al.
Review of Scientific Instruments, 81(2), p.02B101_1 - 02B101_3, 2010/02
Times Cited Count：7 Percentile：34.72(Instruments & Instrumentation)A Multi-Aperture Multi-Grid (MAMuG) accelerator called "MeV accelerator" has been developed for neutral beam injection (NBI) system of ITER. The MeV accelerator succeeded in accelerating 796 keV, 320 mA H ion beam until 2007. However, pulse length was limited to 0.2 s due to un-cooled grids. In the present work, long pulse H ion beam acceleration was performed by the MeV accelerator equipped with water-cooled new grids. The H ion current was increased step by step at certain energy with seeding Cs up to the optimum perveance. At present, pulse length was extended to 5 s for 750 keV, 221 mA (perveance match) and maximum power of 1.01 MJ was achieved (650 keV, 163 mA, 10s). At higher energy and current, pulse length was limited by breakdowns between the grids. This was due to high heat load on A3G and GRG grid by deflection of H ion beam.
Mizuno, Takatoshi; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Tobari, Hiroyuki; Watanabe, Kazuhiro; Dairaku, Masayuki; Sakamoto, Keishi; Inoue, Takashi
Review of Scientific Instruments, 81(2), p.02B103_1 - 02B103_3, 2010/02
Times Cited Count：4 Percentile：22.9(Instruments & Instrumentation)For a neutral beam injector (NBI) of ITER, the negative ion accelerator capable of 1 MeV, 40 A negative ion beam acceleration for up to 3,600 s is required. Suppression of heat load onto acceleration grids is a key issue for the long pulse acceleration of negative ion beams. A major source of the heat load will be from incident of secondary particles, which are neutrals, positive ions and electrons, on the grids. The complicated behavior of secondary particles in the MeV accelerator of JAEA is analyzed using the Electrostatic Accelerator Mote Carlo Code (EAMCC) developed by CEA. Water-cooled new grids were equipped with the MeV accelerator for the long pulse H ion beam acceleration and second acceleration grid (A2G) was removed for simplification. Analytical results for 600 keV H beam acceleration show that the heat load of third acceleration grid (A3G) is inevitably high because of lack of upstream grid, i.e., A2G.
Terasaki, Ryo*; Fujino, Ikuro*; Hatayama, Akiyoshi*; Mizuno, Takatoshi; Inoue, Takashi
Review of Scientific Instruments, 81(2), p.02A703_1 - 02A703_3, 2010/02
Times Cited Count：23 Percentile：68.01(Instruments & Instrumentation)In order to develop the large H ion source for future fusion reactors, the uniform production of H ions is one of the important issues. Recently, it has been shown experimentally in JAEA 10A negative ion source that the non-uniformity of the electron energy distribution function (EEDF) inside the source and the resultant non-uniformity of the H production strongly affect the H beam optics. Therefore, modeling of the EEDF and analysis of the spatial non-uniformity of the EEDF is necessary to optimize H ion source and the beam optics. For this purpose, we are developing the 3D3V Monte Carlo modeling of the EEDF in realistic 3D geometry. The code reproduces the spatial non-uniformity of the EEDF observed in the experiments. Our developing code is a powerful tool for the design of the next generation sources.
-filamentUeno, Akira; Oguri, Hidetomo; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori; Tokuchi, Akira*
Review of Scientific Instruments, 81(2), p.02A718_1 - 02A718_3, 2010/02
Times Cited Count：2 Percentile：13.26(Instruments & Instrumentation) ion source developmentUeno, Akira; Oguri, Hidetomo; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori
Review of Scientific Instruments, 81(2), p.02A720_1 - 02A720_6, 2010/02
Times Cited Count：27 Percentile：72.53(Instruments & Instrumentation)Kashiwagi, Mieko; Taniguchi, Masaki; Dairaku, Masayuki; Grisham, L.*; Hanada, Masaya; Mizuno, Takatoshi; Tobari, Hiroyuki; Umeda, Naotaka; Watanabe, Kazuhiro; Sakamoto, Keishi; et al.
Review of Scientific Instruments, 81(2), p.02B113_1 - 02B113_5, 2010/02
Times Cited Count：8 Percentile：38.09(Instruments & Instrumentation)In JAEA, a multi aperture and multi grid accelerator has been tested for ITER NBI. In recent experiments, it was shown that the acceleration gaps (1st/2nd/3rd/4th/5th gap) have to be expanded from 104/94/87/78/72 in the original to all 100 mm to sustain 200 kV in each stage stably, and 1 MV in total. On the contrary, increases of beam divergence, stripping loss of negative ions and beamlet deflections due to space charge repulsion among beamlets could appear as issues due to the longer gaps. Beam divergence and stripping loss of ions have been examined in a 2D beam optics study utilizing BEAMORBT code and 3D gas flow code, respectively. Beamlet deflections have been examined in a 3D multi beamlet analysis utilizing OPERA-3d code. As results of these simulations, it was clarified that the gap length could be expanded up to 120 mm. This results were applied to design of the accelerator with the long gap of 120 mm.
Tanaka, Yutaka; Hanada, Masaya; Kojima, Atsushi; Akino, Noboru; Shimizu, Tatsuo; Oshima, Katsumi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; et al.
Review of Scientific Instruments, 81(2), p.02A719_1 - 02A719_3, 2010/02
Times Cited Count：4 Percentile：22.9(Instruments & Instrumentation)The JT-60U negative ion source is required to produce 44 A of 500 keV D ion beams for the JT-60SA. So far, acceleration voltage of 450 kV was achieved without beam acceleration and 416 kV with beam acceleration. These are lower than the rated voltage for JT-60SA due to vacuum breakdowns. To examine the cause of vacuum breakdown, the complicated structure of the accelerator was modeled for the calculation of electric field inside the accelerator. At the corners of the grid support flanges, the electric fields are locally concentrated to be 5.2-5.5 kV/mm. This is higher than other parts of the accelerator where the averaged field is around 3 kV/mm. To reduce the concentrated electric field, the support structures were modified to extend the gap lengths between grids. By repeating the high-voltage application of 3 s pulses, the applied voltage was increased. After 15 hours of conditioning, the accelerator sustained its rated value of 500 kV without beam acceleration.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Tobari, Hiroyuki; Grisham, L. R.*; et al.
Review of Scientific Instruments, 81(2), p.02B112_1 - 02B112_5, 2010/02
Times Cited Count：35 Percentile：78.7(Instruments & Instrumentation)The negative-ion based NB injectors on JT-60U achieved maximum injection power of 5.8 MW for 0.9 s via a neutralization of 400 keV, 35 A D ion beams produced in two ion sources. Furthermore, D
beams of 3.4 MW were injected for 20 s using two negative ion sources. The pulse length was limited by power load on the acceleration grids. Reducing the grid power load to an allowable level, long pulse injections was achieved for 30 s at 3 MW. For JT-60SA, 500 keV, 22 A, 100 s beams are required. However, the achieved highest beam energy has been limited to 415 keV. To improve the voltage holding capability, the gap extension and the optimization of the structures have been designed in order to mitigate the local electric field. As a result, the voltage holding capability of 500 kV has been demonstrated. Furthermore, 490 kV for 40 s has been sustained without breakdown. The demonstration of the 500 keV beam acceleration is planned in September 2009 using the modified ion source.
Yoshida, Kenichi; Nara, Takayuki; Saito, Yuichi; Yokota, Wataru
Review of Scientific Instruments, 81(2), p.02A312_1 - 02A312_4, 2010/02
Times Cited Count：2 Percentile：13.26(Instruments & Instrumentation)Kashiwagi, Hirotsugu; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*
Review of Scientific Instruments, 81(2), p.02B724_1 - 02B724_4, 2010/02
Times Cited Count：2 Percentile：13.26(Instruments & Instrumentation)