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Journal Articles

Analysis of interlocked events based on beam instrumentation data at J-PARC Linac and RCS

Hayashi, Naoki; Hatakeyama, Shuichiro; Miura, Akihiko; Yoshimoto, Masahiro; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 7th International Beam Instrumentation Conference (IBIC 2018) (Internet), p.219 - 223, 2019/01

J-PARC is a multi-purpose facility. Accelerator stability is the one of important issues for users of this facility. To realize stable operation, we must collect data on interlocked events and analyze these data to determine the reasons for the occurrence of such events. In J-PARC Linac, data of interlocked events have been recorded using several some beam loss monitors and current monitors, and these data have been are analyzed and classified. In J-PARC RCS, new instrumentation is being introduced to obtain beam position. We discuss the present status and future plans related to this subject.

Journal Articles

Measurement of each 324 MHz micro pulse stripping efficiency for H$$^{-}$$ laser stripping experiment in J-PARC RCS

Saha, P. K.; Okabe, Kota; Miura, Akihiko; Hayashi, Naoki; Harada, Hiroyuki; Yoshimoto, Masahiro

Proceedings of 6th International Beam Instrumentation Conference (IBIC 2017) (Internet), p.233 - 236, 2018/03

Journal Articles

Interlocked events of beam loss monitors at the J-PARC linac

Hayashi, Naoki; Kikuzawa, Nobuhiro; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.540 - 544, 2017/12

The J-PARC linac operation is stable, however, the numbers of interlocked events due to single beam loss monitor (BLMP) is increasing. Recently, the counts is comparable to the number of RFQ trip, and a measure has been required for improvement of the operation efficiency. Thus, every event data has been analyzed and classified into three categories. It is found that there are characteristic signal or pattern of BLMP for every categories. Although the linac BLMP detector is standard, its setting parameters are differ from those of other two synchrotrons in the J-PARC. To optimize time resolution, the input impedance of its pre-amplifier is selected to be 50 $$Omega$$ and interlock is defined in raw signal height and width not integral signal of BLMP. Some new parameters has been tried to reduce unnecessary interlock.

Journal Articles

Beam position measurement during multi-turn painting injection at the J-PARC RCS

Hayashi, Naoki; Saha, P. K.; Yoshimoto, Masahiro; Miura, Akihiko

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.277 - 280, 2017/06

Multi-turn painting injection scheme is important for high intensity proton accelerators. At the J-PARC RCS, a transverse painting scheme was adapted by adding vertical painting magnets to the beam transport line before the injection point, with horizontal painting being performed by a set of dedicated pulse magnets in the ring. To establish a transverse painting condition, it is usual to base on the pulse magnet current pattern. However, it is more desirable to directly measure the beam orbit time variation for evaluation. A linac beam was chopped to match the ring RF bucket. We thought that it would be difficult to measure the position for each pulse; however, the average position could be extracted by introducing a particular device. For the beam injected into the ring, because the linac RF frequency component was diminished due to debunching quickly, one could determine its position in the beginning of the injection period. However, due to rebunching effect the position determination becomes difficult. This problem needs to be resolved.

Journal Articles

Ultra-high temperature tensile properties of ODS steel claddings under severe accident conditions

Yano, Yasuhide; Tanno, Takashi; Oka, Hiroshi; Otsuka, Satoshi; Inoue, Toshihiko; Kato, Shoichi; Furukawa, Tomohiro; Uwaba, Tomoyuki; Kaito, Takeji; Ukai, Shigeharu*; et al.

Journal of Nuclear Materials, 487, p.229 - 237, 2017/04

 Times Cited Count:27 Percentile:96.75(Materials Science, Multidisciplinary)

Ultra-high temperature ring tensile tests were carried out to investigate the tensile behavior of oxide dispersion strengthened (ODS) steel claddings and wrapper materials under severe accident conditions; temperatures ranged from room temperature to 1400$$^{circ}$$C which is near the melting point of core materials. The experimental results showed that tensile strength of 9Cr-ODS steel claddings was highest in the core materials at the ultra-high temperatures between 900 and 1200$$^{circ}$$C, but that there was significant degradation in tensile strength of 9Cr-ODS steel claddings above 1200$$^{circ}$$C. This degradation was attributed to grain boundary sliding deformation with $$gamma$$/$$delta$$ transformation, which was associated with reduced ductility. On the other hand, tensile strength of recrystallized 12Cr-ODS and FeCrAl-ODS steel claddings retained its high value above 1200 $$^{circ}$$C unlike the other tested materials. Present study includes the result of "R&D of ODS ferritic steel fuel cladding for maintaining fuel integrity at the high temperature accident condition" entrusted to Hokkaido University by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

Journal Articles

Evaluation on tolerance to failure of ODS ferritic steel claddings at the accident conditions of fast reactors

Uwaba, Tomoyuki; Yano, Yasuhide; Otsuka, Satoshi; Naganuma, Masayuki; Tanno, Takashi; Oka, Hiroshi; Kato, Shoichi; Kaito, Takeji; Ukai, Shigeharu*; Kimura, Akihiko*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

Tolerance of fast rector fuel elements to failure in the typical accident conditions was evaluated for the oxide-dispersion-strengthened (ODS) ferritic steel claddings that are candidate of the cladding material for advanced fast reactors. The evaluation was based on the cladding creep damage, which was quantified by the cumulative damage fractions (CDFs). It was shown that the CDFs of the ODS ferritic steel cladding were substantially lower than the breach limit of 1.0 in the loss of flow and transient over power conditions until a passive reactor shutdown system operates.

Journal Articles

Beam-loss monitoring signals of interlocked events at the J-PARC Linac

Hayashi, Naoki; Kato, Yuko; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.368 - 371, 2017/03

It is important to understand why the beam loss occurs during user operation. It is understandable that the beam loss results from RF cavities failure. However, it would be still useful to study the beam loss detailed mechanism and to know which beam loss monitor (BLM) experiences the highest loss or is most sensitive. This may lead a reduction in the number of interlocked events and a more stable accelerator operation. The J-PARC Linac BLM has a simple data recorder that comprises multiple oscilloscopes. Although its functionality is limited, it can record events when an interlock is triggered. Of particular interest here are the events associated with only the BLM Machine Protection System (MPS). These may reveal hidden problems with the accelerator.

Journal Articles

Bunch length analysis of negative hydrogen ion beam in J-PARC linac

Miura, Akihiko; Hayashi, Naoki; Maruta, Tomofumi*; Liu, Y.*; Miyao, Tomoaki*; Fukuoka, Shota*

Proceedings of 4th International Beam Instrumentation Conference (IBIC 2015) (Internet), p.386 - 389, 2016/02

We have used bunch shape monitors (BSMs) to measure the longitudinal bunch length of negative hydrogen ion beam in the J-PARC linac. In order to evaluate the measurement errors with peak beam current increasing, we observed waveforms with various beam current. As the result, an RMS bunch length depends on the peak beam current and the bending at the pulse head grows with the peak beam current. We also compared the data taken at an off-center beam to avoid the thermal stress with the ones at an on-center beam, because a target wire will be exposed to a higher peak beam current. In this paper, we introduced the peak beam current dependence of the bunch length waveforms, and an effect of on- /off-centering of the wire position. Finally the new buncher tuning method using one BSM have been discussed.

Journal Articles

Report of ITPA TG Meetings, 52

Shinohara, Koji; Hayashi, Nobuhiko; Isayama, Akihiko; Miyato, Naoaki; Urano, Hajime; Aiba, Nobuyuki

Purazuma, Kaku Yugo Gakkai-Shi, 91(12), p.797 - 800, 2015/12

no abstracts in English

Journal Articles

Beam loss mitigation by the modification of the beam pulse definition in the J-PARC LINAC

Sawabe, Yuki; Maruta, Tomofumi*; Liu, Y.*; Miura, Akihiko; Miyao, Tomoaki*; Ishiyama, Tatsuya; Kikuzawa, Nobuhiro; Hayashi, Naoki

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1202 - 1205, 2015/09

no abstracts in English

Journal Articles

Improvement of the vacuum pressure of the bunch shape monitor at J-PARC linac

Miyao, Tomoaki*; Miura, Akihiko; Kawane, Yusuke; Tamura, Jun; Nemoto, Yasuo; Ao, Hiroyuki*; Hayashi, Naoki; Oguri, Hidetomo; Ouchi, Nobuo; Mayama, Minoru*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1338 - 1341, 2015/09

no abstracts in English

Journal Articles

Development of bunch shape monitor at J-PARC Linac

Futatsukawa, Kenta*; Kawane, Yusuke; Tamura, Jun; Nemoto, Yasuo; Hayashi, Naoki; Fukuoka, Shota*; Mayama, Minoru*; Miura, Akihiko; Miyao, Tomoaki*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1246 - 1250, 2015/09

no abstracts in English

Journal Articles

Report on ITPA meetings, 45

Hayashi, Nobuhiko; Aiba, Nobuyuki; Isayama, Akihiko; Shinohara, Koji; Honda, Mitsuru

Purazuma, Kaku Yugo Gakkai-Shi, 90(6), p.352 - 355, 2014/06

no abstracts in English

Journal Articles

Performance of a total absorption clover detector for $$Q_{beta}$$ measurements of neutron-rich nuclei far from the $$beta$$-stability line

Hayashi, Hiroaki*; Shibata, Michihiro*; Asai, Masato; Osa, Akihiko; Sato, Tetsuya; Koizumi, Mitsuo; Kimura, Atsushi; Oshima, Masumi*

Nuclear Instruments and Methods in Physics Research A, 747, p.41 - 51, 2014/05

 Times Cited Count:10 Percentile:66.19(Instruments & Instrumentation)

To measure $$beta$$-decay energy $$Q_{beta}$$ of short-lived fission products with good accuracy and high efficiency, we have developed a new total absorption clover detector and demonstrated its performance. Using a large-volume clover-type Ge detector having a through-hole in its center, we could measure total absorption spectra of $$beta$$ + $$gamma$$ rays with extremely high efficiency and high energy resolution, and could determine $$Q_{beta}$$ values with $$pm$$30 keV accuracy. Using this detector, we have determined the $$Q_{beta}$$ values of $$^{166}$$Eu and $$^{165}$$Gd for the first time, and of $$^{160-165}$$Eu and $$^{163}$$Gd with better accuracies. In addition, we have observed a new isomeric state in $$^{163}$$Gd, and determined its half-life and excitation energy.

Journal Articles

Development of advanced inductive scenarios for ITER

Luce, T. C.*; Challis, C. D.*; Ide, Shunsuke; Joffrin, E.*; Kamada, Yutaka; Politzer, P. A.*; Schweinzer, J.*; Sips, A. C. C.*; Stober, J.*; Giruzzi, G.*; et al.

Nuclear Fusion, 54(1), p.013015_1 - 013015_15, 2013/12

 Times Cited Count:25 Percentile:79.38(Physics, Fluids & Plasmas)

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 42

Yoshida, Maiko; Shinohara, Koji; Hayashi, Nobuhiko; Isayama, Akihiko; Kamiya, Kensaku

Purazuma, Kaku Yugo Gakkai-Shi, 89(12), p.887 - 889, 2013/12

ITPA (International Tokamak Physics Activity) meetings were held in Autumn 2013.

Journal Articles

Turbulence analyses of improved electron energy confinement in H-mode plasmas with gyrokinetic calculations

Narita, Emi; Honda, Mitsuru; Hayashi, Nobuhiko; Takizuka, Tomonori*; Ide, Shunsuke; Itami, Kiyoshi; Isayama, Akihiko; Fukuda, Takeshi*

Plasma and Fusion Research (Internet), 8, p.1403082_1 - 1403082_8, 2013/06

Journal Articles

Report of International Tokamak Physics Activity meeting, 40

Isayama, Akihiko; Asakura, Nobuyuki; Hayashi, Nobuhiko; Shinohara, Koji; Honda, Mitsuru; Oyama, Naoyuki

Purazuma, Kaku Yugo Gakkai-Shi, 89(6), p.430 - 433, 2013/06

no abstracts in English

Journal Articles

Information of ITPA (International Tokamak Physics Activity) meeting, 38

Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Isayama, Akihiko; Honda, Mitsuru; Urano, Hajime; Nakano, Tomohide

Purazuma, Kaku Yugo Gakkai-Shi, 88(12), p.763 - 767, 2012/12

no abstracts in English

Journal Articles

Analysis of $$T$$$$_{rm e}$$/$$T$$$$_{rm i}$$ effect on confinement properties

Narita, Emi*; Takizuka, Tomonori*; Hayashi, Nobuhiko; Fujita, Takaaki; Ide, Shunsuke; Honda, Mitsuru; Isayama, Akihiko; Itami, Kiyoshi; Kamada, Yutaka; Tanaka, Yasuyuki*; et al.

Plasma and Fusion Research (Internet), 7(Sp.1), p.2403102_1 - 2403102_5, 2012/07

93 (Records 1-20 displayed on this page)