Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

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

https://doi.org/10.1080/00223131.2022.2038301

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.

Reliability of J-PARC accelerator system over the past decade

Yamamoto, Kazami; Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Yoshii, Masahito*; Toyama, Takeshi*

JPS Conference Proceedings (Internet), 33, p.011016_1 - 011016_7, 2021/03

https://doi.org/10.7566/JPSCP.33.011016

The Japan Proton Accelerator Research Complex (J-PARC) is a multipurpose facility for scientific experiments. The accelerator complex consists of a 400-MeV Linac, a 3-GeV Rapid-Cycling Synchrotron (RCS) and a 30-GeV Main Ring synchrotron (MR). The RCS delivers a proton beam to the neutron target and MR, and the MR delivers the beams to the neutrino target and the Hadron Experimental Facility. The first operation of the neutron experiments began in December 2008. Following this, the user operation has been continued with some accidental suspensions. These suspensions include the recovery work due to the Great East Japan Earthquake in March 2011 and the radiation leak incident at the Hadron Experimental Facility. In this report, we summarize the major causes of suspension, and the statistics of the reliability of J-PARC accelerator system is analyzed. Owing to our efforts to achieve higher reliability, the Mean Time Between Failure (MTBF) has been improved.

Status of J-PARC accelerators

Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Yoshii, Masahito*; Yamamoto, Noboru*; Koseki, Tadashi*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1321, 2018/08

After the summer shutdown in 2017, the J-PARC restarted user operation in late October. The Materials and Life Science Experimental Facility (MLF) used a spare target and the beam power was limited to 150-200kW. The target was replaced with a new one in the summer shutdown. The beam power was for user operation gradually increased from 300 kW to 500 kW. We have successfully demonstrated 1MW 1hour operation in July 2018. The beam power for the neutrino experimental facility (NU) was 440 kW to 470 kW. The beam was delivered to the hadron experimental facility (HD) from January to February in 2018. The repetition rate of the main ring was shortened from 5.52 to 5.20 seconds, the beam power was increased from 44 to 50 kW. From March 2018, we delivered to the NU at 490 kW stably. In the fiscal year of 2017, the availabilities for the MLF, NU and HD are 93%, 89% and 66%, respectively.

Status of J-PARC accelerators

Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Hori, Yoichiro*; Yamamoto, Noboru*; Koseki, Tadashi*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1321, 2017/12

After the summer shutdown in 2016, the J-PARC restarted user operation late in October for the neutrino experiments (NU) and early in November for the materials and life science experimental facility (MLF). The beam power for the NU was 420 kW in May 2016, but increased to 470 kW in February 2017 thanks to the change and optimization of operation parameters. For the hadron experimental facility (HD), we started beam tuning in April, but suspended by a failure of the electro static septum. After the treatment, we delivered beam at the power of 37 kW. We delivered beam at 150kW for the MLF. In the fiscal year of 2016, the linac, the 3 GeV synchrotron (RCS) and the MLF were stable and the availability was high at 93%. On the contrary, the main ring has several failures and the availabilities were 77% and 84% for NU and HD, respectively.

Elaboration of the system based code concept; Activities in JSME and ASME, 1; Overview

Asayama, Tai; Miyagawa, Takayuki*; Dozaki, Koji*; Kamishima, Yoshio*; Hayashi, Masaaki*; Machida, Hideo*

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07

https://doi.org/10.1115/ICONE22-30567

This paper is the first one of the series of four papers that describe ongoing activities in the Japan Society of Mechanical Engineers (JSME) and the American Society of Mechanical Engineers (ASME) on the elaboration of the System Based Code (SBC) concept. A brief introduction to the SBC concept is followed by the technical features of structural evaluation methodologies that are based on the SBC concept. Also described is the ongoing collaboration of JSME and ASME at the Joint Task Group for System Based Code established in the ASME Boiler and Pressure Vessel Code Committee which is developing alternative rules for ASME B&PV Code Section XI Division 3, inservice inspection requirements for liquid metal reactor components.

Performance of the beam collimation system in the J-PARC RCS

Yamamoto, Kazami; Kato, Shinichi*; Harada, Hiroyuki; Yoshimoto, Masahiro; Yamazaki, Yoshio; Hayashi, Naoki; Saha, P. K.; Hotchi, Hideaki; Kinsho, Michikazu

Progress in Nuclear Science and Technology (Internet), 4, p.243 - 246, 2014/04

https://doi.org/10.15669/pnst.4.243

The most important issue in a high-intensity proton accelerator is achieving low beam loss operation in order to keep the accelerator tunnel in a hands-on-maintenance condition. To achieve such a condition, a collimation system was designed and installed in the Japan Proton Accelerator Research Complex (J-PARC) 3GeV Rapid Cycling Synchrotron (RCS). The experimental results indicated that the RCS collimation system performs well enough such that nearly all the ring components are maintained in good condition. However, as the beam power increased, unexpected losses downstream of the injection foil increased. Therefore, an additional collimator was installed that successfully reduced such unexpected losses.

Beam emittance control by changing injection painting area in a pulse-to-pulse mode in the 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex

Saha, P. K.; Harada, Hiroyuki; Hayashi, Naoki; Horino, Koki; Hotchi, Hideaki; Kinsho, Michikazu; Takayanagi, Tomohiro; Tani, Norio; Togashi, Tomohito; Ueno, Tomoaki; et al.

Physical Review Special Topics; Accelerators and Beams, 16(12), p.120102_1 - 120102_11, 2013/12

https://doi.org/10.1103/PhysRevSTAB.16.120102

Characteristics of tungsten and carbon dusts in JT-60U and evaluation of hydrogen isotope retention

Ashikawa, Naoko*; Asakura, Nobuyuki; Fukumoto, Masakatsu; Hayashi, Takao; Ueda, Yoshio*; Muroga, Takeo*

Journal of Nuclear Materials, 438, p.S664 - S667, 2013/07

https://doi.org/10.1016/j.jnucmat.2013.01.140

In this study, W concentrations of dusts at P-8 section and hydrogen isotope retentions in dusts are analyzed. Compositions of C including W material dusts were observed in JT-60U. For an enhanced resolution of the XPS measurement to analyze quantitatively the composition of the dust flakes, the new analysis using XPS with indium foil was done and showed that the dust flakes contains about less than 1% of tungsten in carbon. Compositions of tungsten-carbon mixed dusts at different poloidal positions are reported. Produced areas of dust including W is estimated on the outer doom wing by IMPGYRO code. Relative intensities at low temperature regions were smaller than bulk divertor target, which may be caused by the high baking/operation temperature. Amounts of retained Hydrogen/Deuterium in dust particles depend on internal defects and carbon composition of dusts.

Splash plasma channels produced by picosecond laser pulses in argon gas for laser wakefield acceleration

Mizuta, Yoshio*; Hosokai, Tomonao*; Masuda, Shinichi*; Zhidkov, A.*; Makito, Keigo*; Nakanii, Nobuhiko*; Kajino, Shohei*; Nishida, Akinori*; Kando, Masaki; Mori, Michiaki; et al.

Physical Review Special Topics; Accelerators and Beams, 15(12), p.121301_1 - 121301_10, 2012/12

https://doi.org/10.1103/PhysRevSTAB.15.121301

Spatio-temporal mapping; A Technique for overview visualization of time-series datasets

Miyamura, Hiroko; Hayashi, Sachiko*; Suzuki, Yoshio; Takemiya, Hiroshi

Progress in Nuclear Science and Technology (Internet), 2, p.603 - 608, 2011/10

https://doi.org/10.15669/pnst.2.603

Numerical simulations have recently increased in scale and have often output high dimensional datasets. This makes it difficult for users to quickly grasp physical phenomena involved in such datasets. To overcome this difficulty, we propose a spatio-temporal mapping technique (spatio-temporal map) by using an information visualization technique. The spatio-temporal map is generated by mapping the values of a 3D and time-evolving physical quantity into a 2D space with spatial and temporal axes. Here, 3D spatial information is condensed into one dimension by subdividing a target model with an octree. By using the map, users can quickly find regions of interest (ROI). In addition, users can interactively change several aspects of the map such as its resolution and color coding method. By applying the spatio-temporal map to a full-scale 3D vibration simulator for an entire nuclear power plant, we confirmed that the map is a useful technique to quickly identify appropriate ROI.