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Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08
Times Cited Count：51 Percentile：88.9(Physics, Fluids & Plasmas)Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m
for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.
Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 
2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.
Sakaki, Hironao; Nishiuchi, Mamiko; Hori, Toshihiko; Bolton, P.; Yogo, Akifumi; Katagiri, Masaki*; Ogura, Koichi; Sagisaka, Akito; Pirozhkov, A. S.; Orimo, Satoshi; et al.
Applied Physics Express, 3(12), p.126401_1 - 126401_3, 2010/11
Times Cited Count：8 Percentile：34.71(Physics, Applied)Many applications of laser-accelerated ions will require beamlines with diagnostic capability for validating simulations and machine performance at the single bunch level as well as for the development of controls to optimize machine performance. We demonstrated prompt, in-line, single bunch transverse profile and energy spectrum detection using a thin luminescent diagnostic and scintillator-based time-of-flight spectrometer simultaneously. The Monte Carlo code, particle and heavy ion transport code systems (PHITS) simulation is shown to be reasonably predictive at low proton energy for the observed transverse profiles measured by the thin luminescent monitor and also for single bunch energy spectra measured by time-of-flight spectrometry.
Sakaki, Hironao; Nishiuchi, Mamiko; Hori, Toshihiko; Bolton, P.; Yogo, Akifumi; Ogura, Koichi; Sagisaka, Akito; Pirozhkov, A. S.; Orimo, Satoshi; Kondo, Kiminori; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.312 - 315, 2010/08
The beam transport test is carried out through the test beam line of the laser-driven proton accelerator which consists of the phase rotation cavity, PMQ, and bending magnet. The laser system used is J-KAREN at JAEA. The final transmitted bunch duration and transverse profile are well predicted by the PARMILA particle transport code by assuming relatively low initial current of the proton beam. The most probable explanation for this is the space charge neutralization by the laser-plasma-electrons.
Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Bolton, P.; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Mori, Michiaki; Orimo, Satoshi; Pirozhkov, A. S.; et al.
Physical Review Special Topics; Accelerators and Beams, 13(7), p.071304_1 - 071304_7, 2010/07
Times Cited Count：25 Percentile：79.69(Physics, Nuclear)A laser-driven repetition-rated 1.9 MeV proton beam line composed of permanent quadrupole magnets (PMQs), a radio frequency (rf) phase rotation cavity, and a tunable monochromator is developed to evaluate and to test the simulation of laser-accelerated proton beam transport through an integrated system for the first time. In addition, the proton spectral modulation and focusing behavior of the rf phase rotationcavity device is monitored with input from a PMQ triplet. In the 1.9 MeV region we observe very weakproton defocusing by the phase rotation cavity. The final transmitted bunch duration and transverse profile are well predicted by the PARMILA particle transport code. The transmitted proton beam duration of 6 ns corresponds to an energy spread near 5% for which the transport efficiency is simulated to be 10%. The predictive capability of PARMILA suggests that it can be useful in the design of future higher energy transport beam lines as part of an integrated laser-driven ion accelerator system.
Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Bolton, P.; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Mori, Michiaki; Orimo, Satoshi; Pirozhkov, A. S.; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.88 - 90, 2010/05
The concept of a compact ion particle accelerator has become attractive in view of recent progress in laser-driven ion acceleration. We report here the recent progress in the laser-driven proton beam transport at the Photo Medical Research Center (PMRC) at JAEA, which is established to address the challenge of laser-driven ion accelerator development for ion beam cancer therapy.
Sakaki, Hironao; Hori, Toshihiko; Nishiuchi, Mamiko; Bolton, P.; Daido, Hiroyuki; Kawanishi, Shunichi; Sutherland, K.*; Soda, Hikaru*; Noda, Akira*; Iseki, Yasushi*; et al.
Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.1309 - 1311, 2009/05
The concept of a compact ion particle accelerator has become attractive in view of recent progress in laser-driven hadrons acceleration. The Photo Medical Research Center (PMRC) of JAEA was recently established to address the challenge of laser-driven ion accelerator development for hadron beam cancer therapy. PMRC considers conceptual designs of such a therapeutic instrument based on the current state in the laser-driven acceleration. We describe a conceptual gantry device that is designed by the general-purpose ion accelerator design code, PARMILA.
Nishiuchi, Mamiko; Daito, Izuru; Ikegami, Masahiro; Daido, Hiroyuki; Mori, Michiaki; Orimo, Satoshi; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Pirozhkov, A. S.; et al.
Applied Physics Letters, 94(6), p.061107_1 - 061107_3, 2009/02
Times Cited Count：57 Percentile：87.1(Physics, Applied)A pair of conventional permanent magnet quadrupoles is used to focus a 2.4 MeV laser-driven proton beam at a 1 Hz repetition rate. The magnetic field strengths are 55 T/m and 60 T/m for the first and second quadrupoles respectively. The proton beam is focused to a spot size (full width at half maximum) of 2.7
8 mm at a distance of 650 mm from the source. This result is in good agreement with a Monte Carlo particle trajectory simulation.
Onodera, Junichi; Kurihara, Ryoichi; Seki, Yasushi
Gijutsushi Ichiji Shiken No Keiko To Taisaku; Denki Denshi, Joho Kogaku, Genshiryoku, Hoshasen Bumon Hen, p.137 - 178, 2005/08
In 2004, "Nuclear Power and Radiation Section" has been established in the National Qualification of Professional Engineer. A reference material to help those who will take the preliminary examination is produced.
Seki, Yasushi
Genshiryoku eye, 48(6), P. 22, 2002/06
The Human Resources Development (HRD) Project in the framework of the Forum of Nuclear Cooperation in Asia (FNCA) is a very effective mechanism under which the representatives from neighboring 8 countries gather in one place to discuss and exchange information on HRD in nuclear field. Following major tasks are being carried out, (1)Investigate the needs on human resources development in each country and the mutual support activities such as information exchange utilizing internet homepages and exchange of textbooks have been started. More efficient utilization of the existing personnel exchange programs is also being planned. (2)Assistance in the formulation of HRD strategy in each country. (3)Cooperative actions such as exchange of information on the recruitment of young generation to nuclear field, which is an issue common to all member countries.None of these tasks can yield visible results easily. HRD takes much time and effort to build mutual understanding, cooperative relationship and obtain the results together. There is no quick medicine for HRD.
Seki, Masahiro; Hishinuma, Akimichi; Kurihara, Kenichi; Akiba, Masato; Abe, Tetsuya; Ishitsuka, Etsuo; Imai, Tsuyoshi; Enoeda, Mikio; Ohira, Shigeru; Okumura, Yoshikazu; et al.
Kaku Yugoro Kogaku Gairon; Mirai Enerugi Eno Chosen, 246 Pages, 2001/09
no abstracts in English
Kurihara, Ryoichi; Ajima, Toshio*; Ueda, Shuzo; Seki, Yasushi
Journal of Nuclear Science and Technology, 38(7), p.571 - 576, 2001/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Kurihara, Ryoichi; Ueda, Shuzo; Nishio, Satoshi; Seki, Yasushi
Fusion Engineering and Design, 54(3-4), p.465 - 471, 2001/04
Times Cited Count：10 Percentile：59.24(Nuclear Science & Technology)no abstracts in English
Gulden, W.*; Cook, I.*; Marbach, G.*; Raeder, J.*; Petti, D.*; Seki, Yasushi
Fusion Engineering and Design, 51-52(Part.B), p.419 - 427, 2000/11
Times Cited Count：5 Percentile：37.77(Nuclear Science & Technology)no abstracts in English
Nishio, Satoshi; Ushigusa, Kenkichi; Ueda, Shuzo; Polevoi, A.*; Kurita, Genichi; Tobita, Kenji; Kurihara, Ryoichi; Hu, G.; Okada, Hidetoshi*; Murakami, Yoshiki*; et al.
JAERI-Research 2000-029, 105 Pages, 2000/10
JAERI-Research-2000-029.pdf:4.19MB
no abstracts in English
Kikuchi, Mitsuru; Seki, Yasushi; K. Nakagawa*
Fusion Engineering and Design, 48(3-4), p.265 - 270, 2000/09
Times Cited Count：19 Percentile：75.06(Nuclear Science & Technology)no abstracts in English
Seki, Yasushi
Fusion Engineering and Design, 48(3-4), p.247 - 254, 2000/09
Times Cited Count：4 Percentile：32.65(Nuclear Science & Technology)no abstracts in English
Seki, Yasushi; Tabara, Takashi*; Aoki, Isao; Ueda, Shuzo; Nishio, Satoshi; Kurihara, Ryoichi
Fusion Engineering and Design, 48(3-4), p.435 - 441, 2000/09
Times Cited Count：1 Percentile：12.13(Nuclear Science & Technology)no abstracts in English
Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi; Kuroda, Toshimasa*; Miura, H.*; Sako, Kiyoshi*; Takase, Kazuyuki; Seki, Yasushi; Adachi, Junichi*; Yamazaki, Seiichiro*; et al.
Fusion Engineering and Design, 48(3-4), p.271 - 279, 2000/09
Times Cited Count：16 Percentile：70.59(Nuclear Science & Technology)no abstracts in English
Ueda, Shuzo; Nishio, Satoshi; Yamada, Reiji; Seki, Yasushi; Kurihara, Ryoichi; Adachi, Junichi*; Yamazaki, Seiichiro*; Dream Design Team
Fusion Engineering and Design, 48(3-4), p.521 - 526, 2000/09
Times Cited Count：6 Percentile：42.76(Nuclear Science & Technology)no abstracts in English
