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Kamiya, Junichiro; Takano, Kazuhiro*; Wada, Kaoru; Yanagibashi, Toru*
e-Journal of Surface Science and Nanotechnology (Internet), 21(3), p.144 - 153, 2023/06
no abstracts in English
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：5 Percentile：87.42(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Nakanoya, Takamitsu; Kamiya, Junichiro; Yoshimoto, Masahiro; Takayanagi, Tomohiro; Tani, Norio; Kotoku, Hirofumi*; Horino, Koki*; Yanagibashi, Toru*; Takeda, Osamu*; Yamamoto, Kazami
JAEA-Technology 2021-019, 105 Pages, 2021/11
JAEA-Technology-2021-019.pdf:10.25MB
Since a user operation startup, the 3 GeV synchrotron accelerator (Rapid-Cycling Synchrotron: RCS) gradually reinforced the beam power. As a result, the surface dose rate of the apparatus located at the beam injection area of the RCS, such as the magnet, vacuum chambers, beam monitors, etc., increases year by year. The beam injection area has many apparatuses which required manual maintenance, so reducing worker's dose is a serious issue. To solve this problem, we have organized a task force for the installation of the shield. The task force has aimed to optimize the structure of the radiation shield, construct the installation procedure with due consideration of the worker's dose suppression. As the examination result of the shield design, we have decided to adopt removal shielding that could be installed quickly and easily when needed. We carried out shield installation work during the 2020 summer maintenance period. The renewal work required to install the shielding has been carried out in a under high-dose environment. For this reason, reducing the dose of workers was an important issue. So, we carefully prepared the work plan and work procedure in advance. During the work period, we implemented various dose reduction measures and managed individual dose carefully. As a result, the dose of all workers could be kept below the predetermined management value. We had installed removal shielding at the beam injection area in the 2020 summer maintenance period. We confirmed that this shield can contribute to the reduction of the dose during work near the beam injection area. It was a large-scale work to occupy the beam injection area during almost of the summer maintenance period. However, it is considered very meaningful for dose suppression in future maintenance works.
Nakanoya, Takamitsu; Kamiya, Junichiro; Yoshimoto, Masahiro; Takayanagi, Tomohiro; Tani, Norio; Kotoku, Hirofumi*; Horino, Koki*; Yanagibashi, Toru*; Takeda, Osamu*; Yamamoto, Kazami
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.238 - 242, 2021/10
Since a user operation startup, the 3GeV synchrotron accelerator (Rapid-Cycling Synchrotron: RCS) gradually reinforced the beam power. As a result, the surface dose rate of the apparatus located at the beam injection area of the RCS increases year by year. The beam injection area has many apparatuses which required manual maintenance, so reducing worker's dose is a serious issue. To solve this problem, we have decided to adopt removal shielding that could be installed quickly and easily when needed. We carried out shield installation work during the 2020 summer maintenance period. The installation work of the shield has been carried out in a under high-dose environment. For this reason, reducing the dose of workers was an important issue. So, we carefully prepared the work plan and work procedure in advance. During the work period, we implemented various dose reduction measures and managed individual dose carefully. As a result, the dose of all workers could be kept below the predetermined management value. We had installed removal shielding at the beam injection area in the 2020 summer maintenance period. We confirmed that this shield can contribute to the reduction of the dose during work near the beam injection area.
Kamiya, Junichiro; Kotoku, Hirofumi*; Kurosawa, Shunta*; Takano, Kazuhiro; Yanagibashi, Toru*; Yamamoto, Kazami; Wada, Kaoru
Physical Review Accelerators and Beams (Internet), 24(8), p.083201_1 - 083201_23, 2021/08
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)Through the operation of the vacuum system in J-PARC, it becomes evident that the high-power beam has more powerful effects on the vacuum system than expected. Those effects are the malfunction of vacuum equipment and the large pressure rise. The former is the failure of the turbomolecular pump (TMP) controller. The TMP itself is also damaged by a bearing crush due to a touch-down. We have developed a TMP controller that can connect with long cables of more than 200 m lengths to install the controller in a control room where there is no radiation influence. The TMP with high-strength bearing has been also developed. The latter is an extreme pressure rise with increasing the beam power. It is indicated that the pressure rise mechanism is a result of ion-stimulated gas desorption. It is finally confirmed that the dynamic pressure during the high-power beam is effectually suppressed by additionally installing the NEG pumps.
Shobuda, Yoshihiro; Kamiya, Junichiro; Takayanagi, Tomohiro; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; Kotoku, Hirofumi*
Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.3205 - 3208, 2021/08
At the injection area of the RCS in J-PARC, the interaction between the copper stripes (RF-shields) on the ceramic chambers and the external magnetic fields modulatesthe magnetic fields in the chamber, causing beam losses for a special tune. A ceramic chamber spirally covered by the stripes is a candidate to mitigate the modulations. In this report, we numerically and experimentally investigate how the interaction is suppressed, while sustaining the beam impedance enhancement within tolerable at the RCS.
Yamada, Ippei; Kamiya, Junichiro; Nakanoya, Takamitsu; Kurosawa, Shunta*; Yanagibashi, Toru*; Shiga, Takashi; Wada, Kaoru*; Warigai, Keiichi
no journal, ,
no abstracts in English
Yamada, Ippei; Kamiya, Junichiro; Nakanoya, Takamitsu; Kurosawa, Shunta*; Yanagibashi, Toru*; Shiga, Takashi; Wada, Kaoru*; Warigai, Keiichi
no journal, ,
no abstracts in English
