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.

Beam position monitor system of J-PARC RCS

Hayashi, Naoki; Kawase, Masato; Hatakeyama, Shuichiro; Hiroki, Seiji; Saeki, Riuji; Takahashi, Hiroki; Teruyama, Yuzo*; Toyokawa, Ryoji*; Arakawa, Dai*; Hiramatsu, Shigenori*; et al.

Nuclear Instruments and Methods in Physics Research A, 677, p.94 - 106, 2012/06

https://doi.org/10.1016/j.nima.2012.02.013

A beam position monitor (BPM) system at J-PARC RCS is described. The J-PARC RCS is a rapid-cycling proton synchrotron and its designed beam power is 1 MW. A diameter of the BPM detector is larger than 250 mm, however the system has to measure the beam position very accurately. The system should work not only for the high intensity but also for lower intensity. There are 54 BPM around the ring and most of them are placed inside steering magnets because of quite limited space. The BPM detector is an electro static type and it has four electrodes, and a pair of electrode gives a good linear response with diagonal cut shape to detect the charge center precisely. The signal processing unit, which is equipped with 14-bit 40 MSPS ADC and 600 MHz DSP, has been developed. They are controlled via shared memory space and EPICS. It is capable to record full 25 Hz pulse data for averaged mode and it could also store whole waveform data for further analysis, like turn-by-turn position calculation.

Online monitoring of the H0 dump beam current during user operation of J-PARC RCS

Hatakeyama, Shuichiro; Saha, P. K.; Yoshimoto, Masahiro; Yamamoto, Kazami; Hayashi, Naoki; Sato, Kenichiro*

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1013 - 1015, 2010/08

http://www.pasj.jp/web_publish/pasj7/proceedings/P_5PM/P_EH_5PM/THPS076.pdf

In J-PARC (Japan Proton Accelerator Research Complex), the negative hydrogen ions (H) accelerated by LINAC are converted to protons (H) by the Charge Stripping Foil before injecting into RCS (Rapid Cycling Synchrotron). About 99.7% of H are stripped it's two electrons by the 1st foil. The rest of H0 and H are converted to H by 2nd and 3rd foils and abandoned into H0 dump. Monitoring of the fraction of beam current into the H0 dump gives useful information for the stable beam supply during accelerator user's operation. This report describes the method of online monitoring to estimate the beam current of the H0 dump line.

Shot-by-shot beam position monitor system for beam transport line from RCS to MR in J-PARC

Tejima, Masaki*; Arakawa, Dai*; Hashimoto, Yoshinori*; Sato, Kenichiro*; Toyama, Takeshi*; Yamamoto, Noboru*; Hayashi, Naoki; Hanamura, Kotoku*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.978 - 980, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/mope011.pdf

To maintain the beam orbit of beam transport line from RCS to MR in J-PARC (3-50BT), 14 beam position monitors (BPMs) were installed. Their signals gathered in the local control building (D01) have been measured by using 14 digitizing oscilloscopes. The data acquisition system have a performance of shot-by-shot measurement.

Estimation of secondary electron effect in the J-PARC Rapid cycling synchrotron after first study

Yamamoto, Kazami; Kamiya, Junichiro; Ogiwara, Norio; Kinsho, Michikazu; Hayashi, Naoki; Saeki, Riuji; Sato, Kenichiro*; Toyama, Takeshi*

Applied Surface Science, 256(4), p.958 - 961, 2009/11

https://doi.org/10.1016/j.apsusc.2009.05.137

The Japan Proton Accelerator Research Complex (J-PARC) project is a joint project of Japan Atomic Energy Agency (JAEA) and High Energy Accelerator Research Organization (KEK). The accelerator complex of J-PARC consists of a 181 MeV Linac, a 3 GeV Rapid-Cycling Synchrotron (RCS) and a 50 GeV Main Ring (MR). The RCS ring is designed to support 1 MW of beam and to deliver a 3 GeV pulsed proton beam to the spallation neutron target and the MR at a repetition rate of 25 Hz. Since the RCS finally accelerates very high intensity beam, the secondary electron cloud may affect the accelerator performance. The electron cloud effect in RCS was evaluated by simulations, but the secondary electron emission yield (SEY) of the chamber surface and beam loss point, lost proton number were assumed. In this Study we measured the SEY from the samples which was dealt with similar process of an actual chamber surface. We estimate the practical influence of the secondary electron cloud during beam operation.

Beam instrumentations for the J-PARC RCS commissioning

Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyokawa, Ryoji; Yamamoto, Kazami; Yoshimoto, Masahiro; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; Sato, Kenichiro*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.1125 - 1127, 2008/06

A 3-GeV Rapid-Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has been commissioned recently. During its beam commissioning, various beam diagnostic instrumentation has been used. The multi-wire profile monitor (MWPM) is used to establish injection and H0 dump line. The electron catcher confirms that the beam hits a charge exchange carbon foil and the specified current monitor limits the beam current to the H0 dump. Single pass BPMs and ionization profile monitors (IPM) help to check the one pass orbit without circulation of the beam. The beam position monitor (BPM) can measure both COD and turn-by-turn position. Tune monitor system consists of exciter and its own BPM. The exciter shakes the beam and coherent oscillation. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedfoward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning.

Radiation level in the J-PARC Rapid Cycling Synchrotron after first study

Yamamoto, Kazami; Hayashi, Naoki; Hiroki, Seiji; Saeki, Riuji; Toyama, Takeshi*; Teshima, Masaki*; Sato, Kenichiro*

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.382 - 384, 2008/06

https://accelconf.web.cern.ch/e08/papers/mopc133.pdf

The Status of the J-PARC RCS beam monitor system

Hayashi, Naoki; Hiroki, Seiji; Saha, P. K.; Saeki, Riuji; Toyokawa, Ryoji*; Yamamoto, Kazami; Yoshimoto, Masahiro; Arakawa, Dai*; Hiramatsu, Shigenori*; Lee, S.*; et al.

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.243 - 245, 2008/00

The J-PARC RCS has been beam commissioned since fall 2007. During such a short period, the following items have been established. Establishment of the injection orbit, beam circulation, acceleration up to 3GeV, optics parameters measurements and it achieved 50 kW beam power (410 ppb). The beam monitor system has an important role for smooth beam commissioning. This paper describes the status of the beam monitor system, BPM, Injection monitors, IPM, current monitor, tune meter and BLM of the RCS.

Injection and dump line monitor system of J-PARC RCS

Sato, Kenichiro; Hiroki, Seiji; Lee, S.*; Hayashi, Naoki; Yamamoto, Kazami; Hiramatsu, Shigenori*; Toyama, Takeshi*; Arakawa, Dai*; Igarashi, Zenei*; Saeki, Riuji

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.297 - 299, 2007/00

At the injection and H0 dump line of J-PARC RCS, different beam monitors have been installed. Main purpose of the beam monitors in the injection line is to generate a beam position and profile to adjust the injection trajectory to the RCS ring. To guide the injected beam precisely is, needless to say, required to reduce the beam loss in the ring. Hence the monitor system is one of the most essential to operate the RCS. At the injection point, there are also some beams that are not match the RCS ring, that is negative and neutral proton beam. H0 dump accepts the unsuitable beams through the H0 dump line. The power limitation of the H0 dump is 4 kW. The monitor system in the dump line is to handle the beam and to monitor the dumped beam power. At the conference these monitor systems will be outlined.

Developments of residual gas ionization profile monitors for J-PARC RCS and 50 GeV MR

Sato, Kenichiro; Lee, S.*; Toyama, Takeshi*; Hayashi, Naoki

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.115 - 117, 2006/00

3 GeV Rapid Cycling Synchrotron and 50 GeV Main Ring Synchrotron in J-PARC, which is under construction, are expected to accelerate high power proton beam of 1 MW and 0.75 MW class, respectively. To measure such a high intensity beam profile, we have been developing Residual Gas Ionization Profile Monitors (IPMs). To confirm the reliability of this type monitors, we constructed a prototype and installed in Main Ring of Proton Synchrotron at KEK and tested using proton beams for two different operation modes, that is ion and electron collection mode using magnetic guiding field. The obtained data are used to discuss the detection reliability of the real ones.

Study for the establishment of clearance-level verification methodology in Fugen

Kitamura, Koichi; Hayashi, Hirokazu; Morishita, Yoshitsugu; Sakashita, Akira*; Kino, Kenichiro*

no journal, , 

In "Fugen", a turbine system equipment is scheduled to be done in the clearance when it is dismantled for the decommissioning. It is necessary to establish the Clearance examining and approving technique like the method of evaluating the radiation level of the setting of the scaling factor according to the contaminated condition of "Fugen" in advance. The task that undertook the analysis, the evaluation result, and the examining and approving technique establishment of the radiation level for the clearance examining and approving technique establishment that "Fugen" had executed so far and the plan for the future were arranged.