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Watanabe, Yasuhiro; Yanagibashi, Takanori; Komatsuzaki, Makoto*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1024 - 1028, 2023/10
J-PARC RCS accelerates a high-intensity proton beam from 400 MeV to 3 GeV at a repetition rate of 25 Hz. The main magnet system of the RCS is composed of a family of dipole magnets and seven families of quadrupole magnets excited by eight independent resonant circuits. The current control system of the main magnet power supply requires high-precision tracking control between different magnet families. The original control system of the main magnet power supply had been operated without major problems for fifteen years since the start of operation of the RCS, while the control system component is obsolete. We developed a new power supply controller based on SoC FPGA. The controller consists of a main board and four daughter boards and all functions required for current control of the power supply are installed in a 19-inch rack 2U control unit.
Nakanoya, Takamitsu; Yoshimoto, Masahiro; Saha, P. K.; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.629 - 633, 2023/01
In the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS), a 400 MeV H
beam injected from the linac is exchange to an H
beam by a charge exchange foil and accelerated to 3 GeV. The charge exchange foils mainly used in the RCS are HBC foil (Hybrid Boron mixed Carbon stripper foil), which are made by adding a small amount of boron to carbon rods and using them as electrodes by the arc deposition method. Since 2018, foils produced by JAEA have been used for user operation. So far, no major problems have occurred due to the foils. Meanwhile, the beam power of the RCS has been gradually increased from 500 kW to 830 kW since 2018. As beam power increases, the foil issues were identified to achieve the RCS design power of 1 MW. In this paper, we will report on the recent foil usage status and issue in the user operation.
Ono, Ayato; Takayanagi, Tomohiro; Fuwa, Yasuhiro; Shinozaki, Shinichi; Ueno, Tomoaki*; Horino, Koki*; Sugita, Moe; Yamamoto, Kazami; Kinsho, Michikazu; Ikoma, Naoya*; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.395 - 399, 2023/01
At J-PARC, an ignitron is used for the crowbar device of the klystron power supply for high-frequency acceleration of a linear accelerator. Ignitron uses mercury, which is of limited use worldwide, and is expected to be discontinued in the future. Therefore, we designed a semiconductor crowbar switch for short-circuit protection of klystron using a MOS gate thyristor. We have manufactured an oval-type board module that realizes an operating output of 3 kV, 40 kA, and 50 
s per board. For the control power supply to each board module assuming a high voltage of 120 kV, we adopted a self-power supply method that creates a control power supply with a high-voltage DCDC converter from the voltage shared and charged by each board module. It was possible to confirm the operating performance on a 1/2 scale (60 kV, 40 kA) against the voltage of the existing equipment (120 kV, 40 kA) by connecting twenty oval board modules in series. The output test result will be reported.
beamKitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.330 - 332, 2023/01
In the J-PARC linac, a new bunch-shape monitor (BSM) is developed to stably measure the high-intensity and low-energy H beam by improving the strength of the target probe for the heat loading. The new target probe is made of the graphite. The first measurement of the longitudinal beam profile has been realized with the BSM at the core region of the high-intensity beam. Since the beam profile can be measured with the new BSM at any transverse position thanks to the new target probe, we propose the advanced application of the beam diagnostics with the BSM. In this presentation, some new approaches of the beam diagnostics with the BSM; the transverse profile measurement using the secondary electrons and the beam current evaluation from the transverse profile measurement, are discussed beyond the original usage of the BSM.
Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Miyao, Tomoaki*; Miura, Akihiko; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.212 - 214, 2023/01
In the J-PARC linac, the bunch-shape monitor (BSM) is developed to precisely and rapidly measure the longitudinal beam profile at the front-end, towards the improvement of the beam matching. The graphite target having the good strength to the high-power beam, has been introduced in order to resist the heat loading of the high-intensity beam. The resolution and other uncertainties were evaluated for the BSM. The longitudinal Twiss parameters and emittance were measured using the BSM and the IMPACT, which was the 3D particle-in-cell simulation code. The precision of the longitudinal emittance measurement was improved, by implementing uncertainties related to the BSM into the calculation. In this presentation, we will report a series of the measurement result, the method of the beam diagnostics with the BSM at the front-end, and the comparison between the measurement and the beam simulation.
Tamura, Fumihiko; Omori, Chihiro*; Yoshii, Masahito*; Tomizawa, Masahito*; Toyama, Takeshi*; Sugiyama, Yasuyuki*; Hasegawa, Katsushi*; Kobayashi, Aine*; Okita, Hidefumi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.175 - 178, 2023/01
J-PARC MR delivers high intensity proton beams to the neutrino experiment. Eight bunches with high peak currents are extracted from the MR by the extraction kicker, therefore the neutrino beam has the similar structure. Intermediate Water Cherenkov Detector (IWCD) will be installed for the future experiments and the IWCD requires a time structure with low peaks. We consider bunch manipulation at flattop of the MR for reducing the peak current. It should be quickly done to avoid the significant loss of the beam power. The beam gap for the kicker rise time must be kept. We propose a non-adiabatic bunch manipulation using the multiharmonic rf voltage. The longitudinal impedance in the MR can affect the beam stability. The feasibility of the manipulation is discussed by using the longitudinal simulations.
Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Hara, Keigo*; Hasegawa, Katsushi*; Sugiyama, Yasuyuki*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.262 - 266, 2023/01
no abstracts in English
Shibata, Takanori*; Ishida, Masaki*; Nammo, Kesao*; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Shinto, Katsuhiro; Oguri, Hidetomo
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.863 - 867, 2023/01
Continuous operation duration of the J-PARC Radio Frequency (RF) ion source has been extended step by step these years for the goal to supply stable beam during the entire period of J-PARC user operation (around 7 months) each year. A 3651 hours (5 months) continuous ion source operation has been achieved from Nov. 2020 to Apr. 2021. As the lifetime of the ion source is mainly limited by failure on the RF antenna coil, detailed evaluation of the antenna surface condition is required to ensure the feasibility of the further extension of the operation time. In the present study, dimension measurements and SEM/EDS analyses were applied to understand the surface discoloration of the RF antenna. The discoloration after the long-term continuous operation is due to deposition of injected cesium (for H
surface production process) and of stainless used steel (Fe, Cr, Ni) from the ion source components sputtered by plasma. The results show that the enamel coating of the RF antenna has not worn out in the long-term continuous operation for several months and, hence, extension of the ion source continuous operation duration can be extended.
Shobuda, Yoshihiro
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.28 - 32, 2023/01
Two-dimensional resistive-wall impedance of cylindrical chambers with a finite thickness decreases proportionally to the frequency when the skin depth is greater than the chamber thickness. The phenomenon is typically interpreted that the electro-magnetic fields leak out of the chamber over the frequency range. However, the relation among the resistive-wall impedance, the space charge impedance, and the leakage fields from the chamber is not clear. This study provides a more comprehensive picture of dealing with them simultaneously.
Takahashi, Hiroki; Miyao, Tomoaki*; Hatakeyama, Shuichiro; Ishiyama, Tatsuya*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.300 - 304, 2023/01
At J-PARC Linac, some beam dumps (BDs) are used for beam conditioning and study. A beam window is installed in the beamlines of each BD. A beam window protection system has been installed in the Linac 0-deg BD after a trouble with the beam window in 2018. However, the current system has not proved to be fully functional for future beam upgrade plan and etc. Then, we started to develop a beam window protection unit with a new function to measure the beam in real time and to inhibit the beam even in the middle of a beam pulse. In this paper, the details and performance of the developed beam window protection unit will be described.
Fujiyama, Hiroki*; Takahashi, Hiroki; Okabe, Kota; Ito, Yuichi*; Hatakeyama, Shuichiro; Suzuki, Takahiro*; Otsu, Satoru*; Yamakawa, Ryuto*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.529 - 531, 2023/01
Stepper motors are used for mechanical drive in collimators and wire scanner monitors of J-PARC accelerators. Many of these drive unit hardware have been used since the beginning of J-PARC construction, and it is necessary to take measures against aging deterioration. Therefore, we started updating the motor and control system from around 2017. However, when the stepper motor was updated to the current product in the RCS H0 collimator, a malfunction occurred. This is because the drive unit control system cannot correctly recognize the state of the LS (limit switch) due to the noise generated by the motor driver, which hinders the operation. When the noise generated from the old and new stepper motors was measured in a simple test environment for confirmation, it was found that the current product was clearly larger. As a countermeasure, when the wiring of the stepper motor, which was bundled in a single multi-core cable, was separated into separate cables for the power system and LS signal system, the noise level was reduced to about 1/10 and normal operation was restored. I was able to. In this case, we report on noise countermeasures for the RCS H0 collimator drive unit.
Saha, P. K.; Okabe, Kota; Nakanoya, Takamitsu; Yoshimoto, Masahiro; Shobuda, Yoshihiro; Harada, Hiroyuki; Tamura, Fumihiko; Okita, Hidefumi; Hatakeyama, Shuichiro; Moriya, Katsuhiro; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1 - 5, 2023/01
laser stripping at J-PARC RCSSaha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.272 - 276, 2023/01
Yoshimura, Nobuyuki*; Toyama, Takeshi*; Kobayashi, Aine*; Nakamura, Takeshi*; Okada, Masashi*; Shobuda, Yoshihiro; Nakaya, Tsuyoshi*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.936 - 941, 2023/01
no abstracts in English
Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishii, Koji*; Tomizawa, Masahito*; Takeuchi, Yasunao*; Sato, Yoichi*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.19 - 23, 2023/01
In the J-PARC main ring, density modulation due to longitudinal beam instability occurs during the debunching process of coasting beams. This leads to the generation of an electron cloud, which in turn causes transverse beam instabilities. The transverse beam instability causes beam loss and the electron cloud is assumed to cause vacuum degradation, both of which hinder the beam intensity enhancement, so it is essential to clarify the causes and countermeasures. In particular, the longitudinal impedance of several hundred MHz has been investigated as relevant, and measures to reduce the impedance of individual devices are underway. The Eddy-current type septum magnet, newly installed this year, was found to have a large impedance by simulation. Therefore, we are investigating a method to reduce the impedance by a flange loaded with SiC radio wave absorber, which can be applied to locations where there is no spatial margin to install a taper. In this report, we will discuss the characterization of SiC to be used in actual devices, impedance simulation reflecting the results of SiC evaluation, and evaluation of the effect of impedance countermeasures by impedance measurement using the wire method, and progress in evaluating the effect on the beam by beam simulation and beam study.
Oda, Kodai; Takayanagi, Tomohiro; Ono, Ayato; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Morishita, Takatoshi; Iinuma, Hiromi*; Tokuchi, Akira*; Kamezaki, Hiroaki*; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.610 - 614, 2023/01
Kicker system is being used to kick the accelerated 3 GeV beam into the transport lines in RCS of J-PARC. The current kicker power supply applies thyratrons to discharge switches. We are developing a new kicker power supply using next-generation power semiconductors. The timing of the semiconductor switch operation is determined by the input of an external trigger signal. Large timing jitter causes unstable output pulses and beam loss due to beam orbit deviate from reference orbit. Therefore, a low jitter circuit that achieves high repeatability of 2 ns or less will be developed for the new kicker power supply. A prototype trigger generator has been fabricated, and jitter has been evaluated. The results of the evaluation test and the circuit configuration plan for reducing jitter will be reported.
Takayanagi, Tomohiro; Ono, Ayato; Fuwa, Yasuhiro; Shinozaki, Shinichi; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Yamamoto, Kazami; Oguri, Hidetomo; Kinsho, Michikazu; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.242 - 246, 2023/01
At J-PARC, semiconductor short pulse power supplies to replace kicker power supplies and semiconductor long pulse power supplies to replace klystron power supply systems are under construction. We have fabricated a 40kV/2kA/1.2s unit power supply that employs a linear transformer drivers (LTD) system for kickers. Currently, we are working on a high voltage insulating cylinder insulator that suppresses corona discharges using only the insulator structure, without using insulating oil. In addition, the MARX system was adopted for klystron power supply system. A main circuit unit for 8kV/60A/830s rectangular pulse output and an 800V/60A correction circuit unit that improves the flat top droop from 10% to 1% were manufactured. Furthermore, a 2.2kV/2.4kW high voltage SiC inverter charger has been fabricated for this MARX power supply. The presentation will report the evaluation results of each test and prospects for semiconductor pulse power supplies.
Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Koizumi, Mitsuo; Yogo, Akifumi*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.137 - 140, 2023/01
no abstracts in English
Meigo, Shinichiro; Yamaguchi, Yuji; Nakano, Keita*; Sugihara, Kenta*
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.132 - 136, 2023/01
J-PARC accelerator facility is the only accelerator facility in Japan that can provide proton beams in the energy range of 400 MeV or higher. In the J-PARC accelerator facility, it is difficult to install users' experimental equipment inside the proton beam duct in order to maintain stable user operation. In addition, due to the characteristics of the synchrotron accelerator, it is not possible to supply a low-intensity beam enough to confirm the detector. In addition, it is important to improve the intranuclear cascade model (INCL) for high-intensity proton accelerator facilities such as accelerator-driven transmutation systems (ADS), etc. In order to improve the INCL, DDX of the forward-most emitted particles is important, but new data should be obtained since there are few experimental data available. In order to promote space utilization and to improve the accuracy of the INCL, energy spectra of scattered protons at the Al beam window placed at the inlet of the 3NBT dump were measured. In the experiment, plastic scintillators were used with 400 MeV proton beam. The results show that the spectra have sharp peaks due to elastic scattering. The calculation of the PHITS code using INCL reproduced the sharp peak due to elastic scattering well, although it overestimated the contribution of quasi-elastic scattering in the experimental data. In conclusion, it is clear that the present method can be used to utilize protons in several GeV regions for space exploration.
Iwamoto, Hiroki; Meigo, Shinichiro; Nakano, Keita*; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; Yashima, Hiroshi*; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.404 - 409, 2023/01
no abstracts in English
