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Yamamoto, Masanobu; Nomura, Masahiro; Okita, Hidefumi; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*
Progress of Theoretical and Experimental Physics (Internet), 2023(7), p.073G01_1 - 073G01_16, 2023/07
Times Cited Count：0 Percentile：0.01(Physics, Multidisciplinary)The Japan Proton Accelerator Research Complex (J-PARC) Rapid Cycling Synchrotron (RCS) employs Magnetic Alloy (MA) loaded cavities. We realize multi-harmonic rf driving and beam loading compensation owing to the broadband characteristics of the MA. The currently installed cavity is the conventional type one which is designed to be driven by tube amplifiers in a push-pull operation. The push-pull operation has some advantages, i.e., suppressing a higher harmonic distortion without the beam acceleration and shortening the cavity length. However, a disadvantage arises at the high intensity beam acceleration where the multi-harmonic rf driving causes a severe imbalance of the anode voltage swing and restricts the tube operation. Although we have achieved an acceleration for the design beam power of 1 MW, the imbalance becomes an issue to further increase the beam power. We have developed a single-ended MA cavity to avoid such difficulty. The cavity has no tube imbalance intrinsically and it is found that the power consumption to drive the cavity can be reduced compared with the conventional one.
Tamura, Fumihiko
Kasokuki, 18(3), p.151 - 160, 2021/10
The LLRF control system for the J-PARC RCS plays an important role in acceleration of high intensity beams. The original system had been working well without significant problems for more than a decade, however, the long term maintenance became difficult due to the obsolesce of the old FPGAs in the system. Therefore we developed and deployed the next-generation LLRF control system. The next-generation system is based on the modern platform, MTCA.4. The most important new function of the system is the multiharmonic vector rf voltage control feedback, which compensate the heavy beam loading in the wideband cavity better than the feedforward at the beam intensity of the design beam power, 1MW. The commissioning results are reported. The next-generation system has been successfully deployed.
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.
Maekawa, Masaki; Masuno, Shinichi*; Hirano, Takeshi*; Kondo, Masakazu*; Kawasuso, Atsuo; Ito, Hisayoshi; Okada, Sohei
JAERI-Tech 2003-039, 52 Pages, 2003/03
JAERI-Tech-2003-039.pdf:5.14MB
no abstracts in English
Kobayashi, Tetsuya; Chishiro, Etsuji; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*
Proceedings of 27th Linear Accelerator Meeting in Japan, p.302 - 304, 2002/08
For the high-intensity proton linac of the KEK/JAERI joint project, the error of the accelerating field must be within 
1 degree in phase and 1% in amplitude. Thus high phase stability is required to the RF reference distribution system. The 12 MHz RF reference is converted to optical signal and distributed to 50 low level RF control systems of klystron and solid-state amplifier stations through the optical fiber links (E/O, O/E and optical fibers). The phase-stabilized optical fiber (PSOF) will be used as an optical transfer line. Characteristics of the optical components (E/O, O/E, PSOF) are measured. The performance of the conventional E/O and O/E is not enough for the requirements. New optimized E/O and O/E for this linac are going to be produced. The total stability of the RF reference transfer system with new optical components will be evaluated.
*; Okada, Sohei; Kawasuso, Atsuo
JAERI-Conf 97-003, p.472 - 475, 1997/00
no abstracts in English
Yonehara, Hiroto; Suzuki, Hiromitsu; ; *; *; *; *; *; Yokomizo, Hideaki
Proc. of the 1993 Particle Accelerator Conf., 0, p.2039 - 2041, 1993/00
no abstracts in English
Okubo, Makio
Proceedings of 12th Linear Accelerator Meeting in Japan, p.104 - 106, 1987/00
no abstracts in English
Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Hasegawa, Kazuo; Tamura, Jun; Hirano, Koichiro; Ito, Takashi; Nammo, Kesao*; Sugimura, Takashi*; Naito, Fujio*
no journal, ,
The J-PARC accelerator comprises an injector linac, a 3 GeV Rapid-Cycling Synchrotron (RCS) and a Main Ring. Accelerator components in the linac contain a negative hydrogen ion source, a radio-frequency quadrupole (RFQ) linac, drift tube linacs (DTLs), separated-type DTLs, and annular-ring coupled structure (ACS) linacs. Beam commissioning started in November 2006 and beam delivery to users started in 2009. The ACS cavities were installed to increase the energy to the original design of 400 MeV. The new front end (ion source, RFQ, and chopping system) was installed in 2014 to increase the peak beam current from 30 to 50 mA. Currently, a peak current of 50-mA beam is delivered to the RCS with a beam pulse width of 0.27 ms for neutron and muon experiments and 0.1 ms for particle and nuclear experiments with the repetition of 25 Hz. The progress and the operating stability of the RF cavities and measures to maintain performance will be presented.
Morishita, Takatoshi
no journal, ,
Accelerators for Accelerator Driven Systems (ADS) are required to have extremely high operational stability to reduce the fluctuations in the thermal load for the subcritical reactor by beam trips. The J-PARC linac, which is also a high-intensity proton accelerator, has been focused on improving the operational stability of the accelerator to achieve both stable beam quality and high availability. Accelerator cavities in the J-PARC linac contain an RFQ, DTLs, SDTLs, and ACS. Beam commissioning started in November 2006 and beam delivery to users started in 2008. To contribute to the development of ADS accelerators, the operating status of RF accelerator cavities in recent years, especially the RF trips that causes a beam stop, and future improvement plans are presented in this workshop. Additionally, the beam stop event such as equipment failure and the details of preventive maintenance will be reported.
Tamura, Fumihiko
no journal, ,
The LLRF systems based on MTCA.4 in Japan Proton Accelerator Research Complex (J-PARC) are working stably and reliably. They support the stable beam delivery from RCS and MR to the experiments at very high beam power. There are several MTCA applications projects at J-PARC, for example, timing modules and a new feedback system against beam instabilities. A COTS MTCA digitizer is now utilized for beam signal acquisition. The status and future plans of the MTCA applications at J-PARC are presented.
