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Journal Articles

Status of development on LaB$$_6$$ filament arc-driven multi-cusp ion source for iBNCT

Shibata, Takanori*; Takagi, Akira*; Ikegami, Kiyoshi*; Sugimura, Takashi*; Nammo, Kesao*; Naito, Fujio*; Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Honda, Yosuke*; Sato, Masaharu*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.385 - 387, 2018/10

Journal Articles

Monitoring of the injected beam to the J-PARC RCS and BPM design for H0 dump line

Hayashi, Naoki; Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1055 - 1059, 2018/08

The J-PARC Rapid-Cycling Synchrotron (RCS) is designed as an 1-MW high power accelerator. It has been operated since 2007, and its injection energy and beam current are upgraded in 2014. Its operation is very smooth and provides the high intensity beam to the Material and Life science experimental facility (MLF) and the Main Ring (MR). The beam is injected with multi-turn mode. It is possible because the negative hydrogen ion beam from the Linac, H$$^{-}$$, and the circulating proton beam H$$^{+}$$ are different state. The H$$^{-}$$ is converted to H$$^{+}$$ at the injection point, where a charge stripper foil is set. A small fraction of the injected beam, which is not fully stripped, are transferred to the injection beam dump through H0 dump line to prevent un-necessary activation. Since the limit of beam dump is only 4 kW, which is about 3% of designed injection beam power 133 kW, the beam has to be stopped immediately in case of stripper foil break up incident.

Journal Articles

Present status of JAEA-Tokai tandem accelerator

Matsuda, Makoto; Kabumoto, Hiroshi; Tayama, Hidekazu; Nakanoya, Takamitsu; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; Ishizaki, Nobuhiro; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1271 - 1275, 2018/08

The JAEA-Tokai tandem accelerator was operated over a total of 64 days, and delivered 13 different ions to the experiments in the research fields of nuclear physics, nuclear chemistry, atomic physics, solid state physics and radiation effects in material in FY2017. After the vacuum accident occurred in December 2016 the accelerating voltage dropped to 12 MV. In order to remove dust and broken carbon foil in the accelerating tube, all 80 accelerator tubes were removed and rewashed. It took 4 months for cleaning and 2 months for reassembly. Therefore about 10 months were a maintenance period of an accelerator from February 2017. Along with the reconstruction of the accelerating tube, re-alignment of the accelerating tube was carried out. The operation resumed in December 2017 and it was possible to recover the maximum voltage to 17.4 MV without beam and 16.6 MV with beam with periodic conditioning work.

Journal Articles

Next generation LLRF control system for J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1131 - 1135, 2018/08

The LLRF control system for the J-PARC RCS has been playing important roles for acceleration of high intensity proton beams. The key functions of the system are the dual harmonic voltage control and the multiharmonic rf feedforward to compensate the heavy beam loading in the wideband cavities. The system has been working fine for more than ten years, however, the old FPGAs in the system are already discontinued and not supported by current development environment. Maintenance of the system will be difficult soon. We are developing the next generation LLRF control system with the new form factor, MicroTCA.4, while the existing system is based on the VME. In this article, we describe the configuration of the new system, its functions, and the status of the development.

Journal Articles

Development of profile monitors on target for high-intensity proton accelerators

Meigo, Shinichiro; Takei, Hayanori; Matsuda, Hiroki; Yuri, Yosuke*; Yuyama, Takahiro*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1035 - 1039, 2018/08

no abstracts in English

Journal Articles

Development of gas distribution measurement system for a two-dimensional beam profile monitor with a sheet-shaped gas

Yamada, Ippei; Ogiwara, Norio*; Hikichi, Yusuke*; Kamiya, Junichiro; Kinsho, Michikazu

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.88 - 92, 2018/08

no abstracts in English

Journal Articles

J-PARC RCS; Effects of nonlinear field components of injection bump magnets on circulating beam

Hotchi, Hideaki; Harada, Hiroyuki

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.371 - 375, 2018/08

no abstracts in English

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Shibata, Takanori*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira; Namekawa, Yuya*; Oguri, Hidetomo

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.889 - 892, 2018/08

In 2017-2018 campaign, three times of long-time operation more than 2,000 hours of the J-PARC rf-driven negative hydrogen (H$$^{-}$$) ion source producing H$$^{-}$$ beam with the beam current of 47 mA were successfully achieved without any serious problems. At the final day of this campaign, the ion source produced an H$$^{-}$$ beam with the current of 72 mA in order to demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. Approximately 1,400-hour operation with the antenna was successfully performed.

Journal Articles

Progress status of proof-of-principle demonstration of 400 MeV H$$^{-}$$ laser stripping at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Suganuma, Kazuaki; Yamane, Isao*; Irie, Yoshiro*; Liu, Y.*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.806 - 810, 2018/08

Journal Articles

Upgrade of vacuum chamber at RCS beam injection area aimed at lower radiation and maintainability increase

Kamiya, Junichiro; Yamamoto, Kazami; Yanagibashi, Toru*; Sato, Atsushi*; Miki, Nobuharu*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.645 - 648, 2018/08

Surround of the beam injection point in the J-PARC 3 GeV Rapid Cycling Synchrotron is the area where the residual radioactive dose is higher than other areas due to the beam scattering by the charge stripping foil. However, there is very little space to install radiation shields around the vacuum chamber in the beam injection point. Furthermore, the vacuum leak has often occurred due to the heat expansion of the chamber flange due to the induced current by the nearby pulse magnet. To solve such problems for minimizing the radiation exposure of maintenance workers, the vacuum chamber rin the beam injection point was newly designed. The space for the radiation shields was created by lengthening and the changing the cross-sectional shape. The titanium alloy with high mechanical strength was used for the flange material so that the flange was able to be fastened with higher tightening torque.

Journal Articles

Present status of water cooling system at J-PARC linac 2018

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.309 - 311, 2018/08

It is the report to improve the problem of flow reduction in water cooling system resolved completely in summer, 2017. It is continued the phenomenon decreasing the flow (5,800 L/min) of circulating water cooling in DTL and SDTL about 3% per week. By the flow reduction, the entire operation of J-PARC and operation of the accelerator are stopped and low flow contact of flowmeter installed in cavities. The phenomenon is progressed about 9 years since we confirm it and drastic measures for it are aspired. In this report, the point of interest to solve this problem is written. Similarly, it is suggested that the point we should be careful when we use the water cooling system it is one of the utility of J-PARC accelerator. In last summer, the flow reduction is not occur completely as specification changes and replacement of the pumps. Thanks of that, the entire operation and operation of accelerator of J-PARC is operated safety.

Journal Articles

Consideration on grease supply cycle and vibration measurement of rotating equipment

Fujirai, Kosuke; Suganuma, Kazuaki; Yamazaki, Yoshio

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.816 - 818, 2018/08

In order to operate rotating equipment such as a cooling water pump, it is necessary to supply grease suitable for bearings of rotating equipment. The grease replenishment interval has a value recommended by the manufacturer depending on the operation time. However, an abnormal noise occurred earlier than the replenishment cycle. I thought that the current grease replenishment cycle is not suitable for maintenance and management of rotating equipment. Therefore, I tried to search for suitable grease replenishment interval using a vibration sensor installed in the cooling water pump. As a result, it was found that the replenishment interval of grease is too long according to the manufacturer recommended value and should be supplied before the vibration acceleration value increases.

Journal Articles

Development of beam energy position monitor system for RIKEN superconducting acceleration cavity

Watanabe, Tamaki*; Imao, Hiroshi*; Kamigaito, Osamu*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; Fujimaki, Masaki*; Yamada, Kazunari*; Watanabe, Yutaka*; Koyama, Ryo*; Toyama, Takeshi*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.49 - 54, 2018/08

no abstracts in English

Journal Articles

Analysis of carbon thin films by laser Raman method

Kinsho, Michikazu; Kamiya, Junichiro; Koizumi, Oji*; Nasu, Shogo*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.668 - 670, 2018/08

Crystallinity, crystalline structure and internal force of thin films were measured by Laser Raman spectroscopy for the purpose of analyzing the fracture mechanism of the charge exchange foil due to beam hitting in this study. Thin films were used four types of HBC foil, pure carbon film (C foil) formed by arc discharge method, graphene, and carbon nanotube (CNT foil). As a result of changing the laser output and measuring the Raman peak shift of each foil, the HBC foil and the C foil had large Raman peak shift change, the D-band was negative and the G-band was opposite sign with positive. On the other hand, the graphene and the CNT foil showed small change in Raman peak shift, and both D-band and G-band were negative. From these results, it was found that a large stress occurs in the HBC foil and the C foil due to the heat load by the laser which was used for Raman spectrum measurements.

Journal Articles

Brazing of alumina ceramics and pure titanium

Kinsho, Michikazu; Kamiya, Junichiro; Abe, Kazuhiko*; Nakamura, Tomaru*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1177 - 1179, 2018/08

Alumina ceramics vacuum Chamber which is used for the RCS in J-PARC is composed of alumina duct, titanium (Ti) flanges and Ti sleeves. Before brazing the alumina duct and the Ti sleeves, the Ti sleeves were treated with Nitric acid-Hydrofluoric acid. The purpose of this study is to clear the effect of this treatment for titanium material. It was cleared that the roughness of the titanium material after the Nitric acid-Hydrofluoric acid treatment becomes big for SEM observation. It was also measured that the thickness of oxide film on surface of the titanium material was 12.7 nm before treatment and 6.0 nm after treatment. As a result of measuring the wettability of the brazing material which was silver brazing filler metal (Ag:72%, Cu:28%) on the Ti surface and the diffusion of the Ti material into the brazing material, it became clear that the vacuum condition of the vacuum heating furnace was important for brazing between alumina ceramics and pure titanium.

Journal Articles

Beam profile measurement using carbon nanotube wires, 3; Beam profiles in high energy part in linac

Miyao, Tomoaki*; Miura, Akihiko

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1031 - 1034, 2018/08

no abstracts in English

Journal Articles

Development of laser system for a proof-of-principle experiment of laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Inoue, Shunsuke*; Sato, Atsushi*; Suganuma, Kazuaki; Yamane, Isao*; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.811 - 815, 2018/08

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses occur by scattering at the foil. Additionally, the beam collision at the foil may cause the break itself. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. We newly propose and develop a laser stripping injection scheme. At the first step, we propose a proof-of-principle (POP) experiment of the scheme in J-PARC and develop a laser system. In this presentation, we will introduce the laser stripping injection scheme and describe an overview of a POP experiment. We will report a current status of the laser system.

Journal Articles

Status of 3 MeV beam scrapers for the J-PARC LINAC

Hirano, Koichiro; Sugimura, Takashi*; Kurihara, Toshikazu*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.324 - 328, 2018/08

We could use a 3 MeV beam scraper without a problem for five months when the scraper received to 1.3 times as high as a normal average beam current of the scraper in 1MW beam operation. The peak temperature on the scraper surface was 1800$$^{circ}$$C. Irradiation damage caused by the 3 MeV beam with particle number of 3E22 was 700 $$mu$$m depth. We study scraper materials which can withstand the current density higher than carbon composite used in the scraper because almost all beams can be irradiated to the scraper in 1 MW beam operation. Beam irradiation tests have been performed about graphene and tungsten as scraper materials with high heat conductivity. This paper describes beam irradiation test of the 3 MeV beam scraper and scraper materials.

Journal Articles

Standardization of stepping motor control system in J-PARC Linac and RCS

Takahashi, Hiroki; Sawabe, Yuki; Suzuki, Yasuo*; Suzuki, Takahiro*; Kawase, Masato*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1105 - 1108, 2018/08

J-PARC Linac and RCS Profile Monitor and etc. are devices consisting of moving parts and driving part. In these devices, in order to move the movable part to an appropriate position without damaging it, proper control of the stepping motor used for the driving part is important. Many of the control system hardware of these drive units are used since the early days of J-PARC operation, and there is concern about malfunctions due to aging. In addition, since both VME and PLC are used as controllers, it is necessary to prepare spare parts of both control equipment in maintenance and management. Besides, the control logic differs depending on the kind of controller, VME or PLC. Therefore, maintainability of both hardware and software is an important issue. Then, we decided to proceed with updating the drive unit control system which standardized control system hardware and software. In this paper, the standardization of stepping motor control system in Linac and RCS is detailed.

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