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Journal Articles

Fast fault recovery scenarios for the JAEA-ADS linac

Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Nakano, Keita; Takei, Hayanori; Maekawa, Fujio; Meigo, Shinichiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.61 - 65, 2021/10

Japan Atomic Energy Agency (JAEA) is designing a 30 MW CW superconducting proton linac as a major component for the accelerator-driven subcritical system (ADS) project. The main challenge of the linac operation is the high reliability required to suppress thermal stress in the subcritical reactor. To this end, we implemented fault compensation schemes to enable a fast beam recovery; consequently, reducing the beam trip duration. This work presents strategies to increase the fault-tolerance capacity of the JAEA-ADS linac.

Journal Articles

Experimental verification of magnetic field measurement probe for RCS bump magnet

Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Takayanagi, Tomohiro; Ono, Ayato; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.641 - 644, 2021/10

In the J-PARC 3 GeV Rapid Cycling Synchrotron (RCS), shift bump magnets are used to merge the injection beam from the LINAC with the circulating orbit of the RCS. The bump magnets are excited with a trapezoidal pulse waveform, that the rise / fall time and the duration of the flat part can be changed. The injection bump orbit is created by the pulse waveform to inject a 1 MW, high intensity beam at a repetition rate of 25 Hz. An issue to achieve the 1 MW beam is suppression of the beam loss. Therefore, a requirement of the accuracy of the magnetic field is less than $$pm$$0.2%. Since the time structure of the pulse is so fast, we needed a test to select a magnetic probe with a suitable response. In this report, we will show the results of comparing the search coil, Hall probe and integral flux meter. The result indicated that the integral flux meter with a small measurement error is suitable.

Journal Articles

Development of semiconductor clover switch for short-circuit protection of Klystron for J-PARC accelerator

Ono, Ayato; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.831 - 834, 2021/10

The Ignitron is used in the clover device of the klystron power supply for RF acceleration in the J-PARC LINAC. However, this ignitron uses mercury, the use of which is restricted worldwide, and its production is expected to be discontinued in the future. Therefore, we designed a semiconductor clover 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 $$mu$$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 1/4 scale (30 kV, 40 kA) against the voltage of the existing equipment (120 kV, 40 kA) by connecting ten oval board modules in series. The output test result will be reported.

Journal Articles

Neutron measurement in the accelerator tunnel of J-PARC Rapid Cycling Synchrotron

Yamamoto, Kazami; Hatakeyama, Shuichiro; Otsu, Satoru*; Matsumoto, Tetsuro*; Yoshimoto, Masahiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.494 - 498, 2021/10

J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) provides more than 700 kW proton beam to the neutron target. In order to investigate the influence of the radiation, we intend to evaluate the radiations such as the neutron and gamma-rays, which are generated due to the proton beam loss. If the amount of beam loss is excessive, it becomes difficult to identify the individual neutron and gamma ray. Therefore, we investigated the signal rate of the extraction point of RCS. Preliminary result indicated that we can enough distinguish the neutron and gamma-ray by the liquid scintillator.

Journal Articles

Present status of JAEA-Tokai tandem accelerator

Matsuda, Makoto; Tayama, Hidekazu; Ishizaki, Nobuhiro; Kabumoto, Hiroshi; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; Abe, Shinichi

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.394 - 398, 2021/10

no abstracts in English

Journal Articles

Durability of secondary electron emission for high-intensity beam on SiC wire

Meigo, Shinichiro; Nakano, Keita; Okubo, Nariaki; Yuyama, Takahiro*; Ishii, Yasuyuki*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.296 - 301, 2021/10

no abstracts in English

Journal Articles

Titanium nitride-coated ceramic break for wall current monitors with an improved broadband frequency response

Shobuda, Yoshihiro; Toyama, Takeshi*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.75 - 79, 2021/10

The beam impedance of a ceramic break with thin titanium nitride coating (TiN) consists of resistive wall term caused by TiN, radiation term, and capacitive term made by the ceramic itself in parallel. The entire wall current continues to run in TiN even when the skin depth is much larger than the chamber thickness, except for the extremely thin TiN. This characteristic is useful in developing a wall current monitor with an improved frequency response.

Journal Articles

Evaluation of the frequency response of the RF gap voltage monitor of the J-PARC RCS

Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Hara, Keigo*; Hasegawa, Katsushi*; Sugiyama, Yasuyuki*; et al.

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.840 - 844, 2021/10

The J-PARC RCS employs the dual-harmonic operation, in which the fundamental and the second harmonic RF voltages are used for the beam acceleration. The each harmonic voltage and phase applied for the acceleration gaps are controlled by the multiharmonic vector RF voltage control system using the signal from the cavity gap voltage monitor equipped with the one of the acceleration gaps of the each RF cavity. Since the bunch shape varies depending on the relative phase of each harmonic, it is important to evaluate the frequency response of the cavity gap voltage monitor. The measurements of frequency response of the cavity gap voltage monitor and beam tracking simulation considering the measurement were carried out. As a result, it was confirmed that the bunch shape of the beam tracking simulation reproduces the one measured at the 1MW beam operation well. The details of the frequency response measurement, the beam tracking simulation and the discussion of the cavity gap voltage monitor circuit are reported.

Journal Articles

Performance of the next-generation LLRF control system for the J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Yamamoto, Masanobu; Okita, Hidefumi; Omori, Chihiro*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*; et al.

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.170 - 174, 2021/10

A stable and precise LLRF (Low Level RF) control system is indispensable for acceleration of high intensity proton beam in the J-PARC RCS. The original LLRF control system had been operated without major problems for more than ten years since the start of operation of the RCS, while maintenance of the system became difficult due to the obsolesce of the old FPGAs in the modules. We developed and installed the next-generation LLRF control system based on MTCA.4. The key function of the system is the multiharmonic vector rf voltage control feedback. We describe the system overview and the commissioning results. The performance of the beam loading compensation is significantly improved.

Journal Articles

Evaluations with autoencoder whether the image used for image recognition is appropriate

Nomura, Masahiro; Okita, Hidefumi; Shimada, Taihei; Tamura, Fumihiko; Yamamoto, Masanobu; Furusawa, Masashi*; Sugiyama, Yasuyuki*; Hasegawa, Katsushi*; Hara, Keigo*; Omori, Chihiro*; et al.

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.80 - 82, 2021/10

no abstracts in English

Journal Articles

Radiation shielding installation for beam injection section of 3GeV synchrotron

Nakanoya, Takamitsu; Kamiya, Junichiro; Yoshimoto, Masahiro; Takayanagi, Tomohiro; Tani, Norio; Kotoku, Hirofumi*; Horino, Koki*; Yanagibashi, Toru*; Takeda, Osamu*; Yamamoto, Kazami

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.238 - 242, 2021/10

Since a user operation startup, the 3GeV synchrotron accelerator (Rapid-Cycling Synchrotron: RCS) gradually reinforced the beam power. As a result, the surface dose rate of the apparatus located at the beam injection area of the RCS increases year by year. The beam injection area has many apparatuses which required manual maintenance, so reducing worker's dose is a serious issue. To solve this problem, we have decided to adopt removal shielding that could be installed quickly and easily when needed. We carried out shield installation work during the 2020 summer maintenance period. The installation work of the shield has been carried out in a under high-dose environment. For this reason, reducing the dose of workers was an important issue. So, we carefully prepared the work plan and work procedure in advance. During the work period, we implemented various dose reduction measures and managed individual dose carefully. As a result, the dose of all workers could be kept below the predetermined management value. We had installed removal shielding at the beam injection area in the 2020 summer maintenance period. We confirmed that this shield can contribute to the reduction of the dose during work near the beam injection area.

Journal Articles

Update of MPS modules for J-PARC linac and RCS, 2

Takahashi, Hiroki; Suzuki, Takahiro*; Ishiyama, Tatsuya*; Ito, Yuichi*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.914 - 917, 2021/10

In the event of an abnormal situation, a machine protection system (MPS) that immediately inhibits the beam is indispensable to minimize the damage and the radioactivation by beam loss. The existing MPS was developed during the construction period, and there are many MPS modules that have been used from the beginning of J-PARC operation, Therefore, as a measure against aging, we started designing, manufacturing and updating the new MPS module in 2018. In this paper, the specifications and the results of performance test about the newly designed and manufactured the MPS signal aggregation module and the E/O converter module will be described.

Journal Articles

LTD semiconductor switch power supply for J-PARC kicker

Takayanagi, Tomohiro; Ono, Ayato; Horino, Koki*; Ueno, Tomoaki*; Sugita, Moe; Togashi, Tomohito; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.53 - 57, 2021/10

We are developing the LTD semiconductor switch power supply, which combines SiC-MOSFET semiconductors and Linear Transformer Drivers (LTD) circuit to replace the kicker power supply in J-PARC. This power supply consists of two types of circuit boards: a main circuit board for forming rectangular pulses and a correction circuit board for compensating for flat-top droop, which enables high-voltage output and droop compensation for the number of stages connected in a hierarchical series. In addition to the main circuits of the thyratron, PFN, and end-clipper, which are the main circuit board is a single 400 mm $$times$$ 430 mm board with a reflected wave absorption circuit that can reduce the beam impedance from the kicker magnet. In this study, we used 32 main circuit boards with 1.7 kV SiC-MOSFETs and 20 compensation boards with 100V MOSFETs to achieve the required 40 kV output rating as a kicker power supply. The evaluation results will be reported.

Journal Articles

Initiatives to address the lifetime improvement of HBC stripper foil for 3GeV synchrotron of J-PARC

Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10

no abstracts in English

Journal Articles

Evaluation and countermeasures for impedance of fast extraction septa and fast extraction kickers at the J-PARC main ring

Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishii, Koji*

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.287 - 291, 2021/10

no abstracts in English

Journal Articles

Evaluation by causality for measurement data of longitudinal coupling impedances with stretched-wire method

Toyama, Takeshi*; Kobayashi, Aine*; Shobuda, Yoshihiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.666 - 669, 2021/10

no abstracts in English

16 (Records 1-16 displayed on this page)
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