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Okudaira, Takuya*; Tani, Yuika*; Endo, Shunsuke; Doskow, J.*; Fujioka, Hiroyuki*; Hirota, Katsuya*; Kameda, Kento*; Kimura, Atsushi; Kitaguchi, Masaaki*; Luxnat, M.*; et al.
Physical Review C, 107(5), p.054602_1 - 054602_7, 2023/05
Times Cited Count:0 Percentile:70.47(Physics, Nuclear)no abstracts in English
Endo, Shunsuke; Okudaira, Takuya*; Abe, Ryota*; Fujioka, Hiroyuki*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Oku, Takayuki; Sakai, Kenji; Shima, Tatsushi*; et al.
Physical Review C, 106(6), p.064601_1 - 064601_7, 2022/12
Times Cited Count:1 Percentile:54.36(Physics, Nuclear)no abstracts in English
Koga, Jun*; Takada, Shusuke*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Niinomi, Yudai*; Okudaira, Takuya*; et al.
Physical Review C, 105(5), p.054615_1 - 054615_5, 2022/05
Times Cited Count:2 Percentile:68.81(Physics, Nuclear)no abstracts in English
Okudaira, Takuya*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Niinomi, Yudai*; Sakai, Kenji; et al.
Physical Review C, 104(1), p.014601_1 - 014601_6, 2021/07
Times Cited Count:3 Percentile:58.42(Physics, Nuclear)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
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.
Yamamoto, Tomoki*; Okudaira, Takuya; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.
Physical Review C, 101(6), p.064624_1 - 064624_8, 2020/06
Times Cited Count:8 Percentile:74.44(Physics, Nuclear)Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Yoshii, Masahito*; Toyama, Takeshi*; Yamamoto, Noboru*; et al.
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1235 - 1239, 2019/07
After the summer shutdown in 2018, the J-PARC restarted user operation in late October. While beam power to the Materials and Life Science Experimental Facility (MLF) was 500 kW as before the summer shutdown, linac beam current was increased from 40 to 50 mA. Operation of the Main Ring (MR) was suspended due to the modification and/or maintenance of the Superkamiokande (neutrino detector) and Hadron experimental facility. The user operation was resumed in the middle of February for the Hadron experimental facility at 51 kW. But on March 18, one of the bending magnets in the beam transport line to the MR had a failure. It was temporary recovered and restored beam operation on April 5, but the failure occurred again on April 24 and the beam operation of the MR was suspended. In the fiscal year of 2018, the availabilities for the MLF, neutrino and hadron facilities are 94%, 86%, and 74%, respectively.
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.
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio; Koseki, Tadashi; Yamamoto, Noboru; Yoshii, Masahito
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1038 - 1040, 2018/06
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.
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio*; Koseki, Tadashi*; Yamamoto, Noboru*; Hori, Yoichiro*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2290 - 2293, 2017/06
The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). We have taken many hardware upgrades such as front end replacement and energy upgrade at the linac, vacuum improvement, collimator upgrade, etc. The beam powers for the neutrino experiment and hadron experiment from the MR have been steadily increased by tuning and reducing beam losses. The designed 1 MW equivalent beam was demonstrated and user program was performed at 500 kW from the RCS to the neutron and muon experiments. We have experienced many failures and troubles, however, to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.
Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Naito, Fujio*
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1409 - 1412, 2016/11
After the summer maintenance in 2015, user operation for the hadron experimental facility (HD) and the life science experimental facility (MLF) was resumed in the middle of October after the tuning of accelerator at J-PARC. In December, we reduced the repetition cycle from 6.0 seconds to the 5.52 seconds at the main ring (MR) and therefore, we have improved beam power to 42 kW, while it was 24 kW in April. The peak beam current at the linac by December 2015 was 30 mA, but we have increased to 40 mA in January, and the tuning was followed by the 3 GeV synchrotron (RCS) and the MR for user operation condition. As a result we improved a beam power to the neutrino experimental facility (NU) to 390 kW by the tuning while it was ranged 300 to 330 kW at 30 mA. User program was performed at 500 kW at the MLF, but it was suspended by a defect of a target in November. It was replaced for a spare one and resumed at 200 kW in February. We have several faults to stop beam operations: ventilation system at the linac by a short circuit, a vacuum leak at the RCS collimator, a breakdown of bending magnet of the MR, etc.
Murai, Yuichi*; Yoshikawa, Shinji; Toda, Shinichi*; Ishikawa, Masaaki*; Yamamoto, Fujio*
Nuclear Engineering and Design, 236(1), p.94 - 106, 2006/01
Times Cited Count:64 Percentile:96.74(Nuclear Science & Technology)Air-water two-phase flow in helicallly coiled tube of 20mm in the internal diameter is investigated ezperimentally to elucidate the effect of centrifugal acceleration on the flow regime map and the local instantaneous flow structure. Three kinds of test tubes including a straight tube are used to compare the flow structure under turbulent flow condition. The superficial velocity up to 6 m/s is tested so that centrifugal Froude number covers a range from 0 to 3. The inter facial structure is visualized from two directions by a high-speed video system with a synchronized measurement of local pressure fluctuation. The results reveral that the flow transition line alters due to centrifugal force acting on liquid phase in the tube. Especially the bubbly fow regime is narrwed significantly. The pressure fluctuation amplitude gets large relatively to the average presure loww as void fraction increases. The Frequency spectra of the pressure fluctuation have plural peaks in the case of strong curvature, implying that the periodicity of slugging two-phase flow is collapsed by internal secondary flow actibated inside liquid phase. Moreover, the substantial velocity of gas phase is slower than the total superficial velocity in case of large Froude number because of biased distribution to the inner surface allowing liquid flow passing outside as like a radial stratified flow.
Murai, Yuichi*; Oiwa, Hiroshi; Sasaki, Toshio*; Kondo, Masahiko; Yoshikawa, Shinji; Yamamoto, Fujio*
Measurement Science and Technology, 16(7), p.1459 - 1468, 2005/07
Times Cited Count:30 Percentile:81.54(Engineering, Multidisciplinary)Air-water two-phase flow in a helically coiled tube is investigated using backlight imaging tomography to elucidate the effect of centrifugal acceleration on phase distribution and interfacial structure. Superficial velocities up to 6m/s in 20mm-diameter tube are tested. We focused on a slug flow regime in which centrifugal acceleration dominates the flow. The interfacial structure is visualized in six directions using a set of originally designed mirror-mounted water jackets. A temporal expansion image is made from line-sampled images, and is used to reconstruct phase distribution through a linear backward projection algorithm. The present topography measurement showed various new features of gas-liquid two-phase flow in a helically coiled tube, such as a wall-covering effect in the case of high superficial velocity.
Oiwa, Hiroshi; Murai, Yuichi*; Sasaki, Toshio*; Yoshikawa, Shinji; Yamamoto, Fujio*
Proceedings of 4th World Congress on Industrial Process Tomography, Vol.1, p.428 - 433, 2005/00
We carried out reflection seismic and multi-offset VSP surveys at JNC Shobasama-site to develop the investigation technique in the granite area, and evaluated the applicability of these geophysical methods. As the result of this study, we consider that a) It is possible to infer the existence of the lower angle fracture zone in the granite by eflection seismic survey and b) Multi-offset VSP supplements the result of reflection seismic survey and it is possible to infer the distribution of the fracture zone in deeper area in the granite.
Murai, Yuichi*; Yamamoto, Fujio*; Ishikawa, Masaaki*; Sakai, Kosuke*; Oiwa, Hiroshi*; Toda, Shinichi; Yoshikawa, Shinji; Tamayama, Kiyoshi
JNC TY4400 2003-006, 75 Pages, 2003/06
None
Oga, Tokumichi; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.
Review of Scientific Instruments, 73(2), p.1058 - 1060, 2002/02
Times Cited Count:12 Percentile:55.36(Instruments & Instrumentation)no abstracts in English
Kawai, Mikito; Akino, Noboru; Ebisawa, Noboru; Honda, Atsushi; Ito, Takao; Kazawa, Minoru; Kuriyama, Masaaki; Mogaki, Kazuhiko; Oga, Tokumichi; Ohara, Hiroshi; et al.
JAERI-Tech 2001-073, 98 Pages, 2001/11
The world's first negative-ion based neutral beam injector(N-NBI) system has been developed for studies of non-inductive current drive and plasma core heating with high energy neutral beam injection in higher density plasma. Construction of the N-NBI system for JT-60U was completed in March 1996. The system is composed of a beamline with two ion souces, a set of ion source power supllies, control system and auxiliary sub-system such as cooling water, refrigeration and vaccum system. In July 2001, deuterium neutral beam injection of 400keV and 5.8MW into JT-60U plasma was achieved. In order to increase both beam power and energy we have to go on more improvement of the N-NBI.
Sakurai, Kiyoshi; Kume, Etsuo; Yatabe, Shigeru*; Maekawa, Fujio; Yamamoto, Toshihiro; Nagaya, Yasunobu; Mori, Takamasa; Ueki, Kotaro*; Naito, Yoshitaka*
JAERI-Review 2000-034, 133 Pages, 2001/02
no abstracts in English
Sakurai, Kiyoshi; Kume, Etsuo; Yatabe, Shigeru*; Maekawa, Fujio; Yamamoto, Toshihiro; Nagaya, Yasunobu; Mori, Takamasa; Ueki, Kotaro*; Naito, Yoshitaka*
Nihon Genshiryoku Gakkai-Shi, 42(10), p.1062 - 1065, 2000/10
no abstracts in English