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Hatakeyama, Shuichiro; Yoshimoto, Masahiro; Yamamoto, Kazami
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.475 - 477, 2020/09
J-PARC accelerators consist of linear accelerator (LINAC), 3GeV synchrotron (RCS) and main ring synchrotron (MR). RCS is an important facility delivering the beam to Materials and Life Science Experimental Facility (MLF) and MR. In RCS 87 proportional counter type beam loss monitors (PBLM) are installed and it is protecting the equipments on the beam line from the radioactivation by alerting the machine protection system (MPS) when the integrated value of the beam loss in an accelerating cycle gets over the limit. In this presentation, -1000V to -2000V high voltage are adapted to PBLMs and output was measured. In result, some PBLMs where the beam loss is large enough, there are saturations around -1400V to -2000V about the peak value of beam loss but no saturation about integral value of beam loss. Also it is considered the new HV system which solves some issues of the on-going HV system.
Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.33 - 37, 2020/09
Japan Atomic Energy Agency (JAEA)- Accelerator Driven System (ADS) linac consists of a CW proton accelerator with a beam current of 20 mA driven with the energy of 1.5 GeV. Most of the beam acceleration is achieved by using superconducting cavities to obtain high acceleration efficiency at CW mode. The main superconducting linac is composed of five families of cavities (Half Wave resonators, Spokes resonators, and Elliptical cavities) with theirs respectively magnets. Due to the large beam power in the linac of 30 MW and the high reliability required for the ADS project, a robust beam optic designed is necessary to have a stable beam operation and control the beam loss power. The JAEA-ADS linac is composed of several sections and components; thus, the misalignment of these elements together with field errors enhance the beam loss rate and compromises the safety of the linac. To this end, an error linac campaign was launched to estimate the error tolerance of the components and implement a correction scheme to reduce the beam loss power around the linac.
Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.441 - 445, 2020/09
The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme is destructive-type method by using the foil and can accumulate high intensity proton beam. However, the uncontrolled beam losses by scattering at the foil and the foil breaking by the beam collision are a key issue of high-intensity proton accelerator. In order to realize higher intensity, new injection scheme of non-destructive type is needed instead of the foil. We newly propose laser stripping injection scheme by using laser pulse. We plan proof of principle experiment at J-PARC and are developing the laser system. In my presentation, we introduce the overview of laser stripping injection scheme and report the status of laser development.
Hayashi, Naoki
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.478 - 481, 2020/09
Measurement of beam intensity or beam current is the one of the most important beam diagnostic in an accelerator. At J-PARC Rapid-Cycling Synchrotron (RCS), there are two kinds of beam intensity monitors and multiple Current Transformers (CT) with various bandwidth. The RCS is a high intensity proton accelerator and its designed beam power of 1 MW. The beam power delivered to users gradually increases in the recent year. Single pulse or short term with designed beam power has been also demonstrated. In addition, beyond 1-MW equivalent intensity has been attempted. Through the experience with achievement of the design goal and the operation beyond it, intensity dependence of beam current measurement has been summarized.
laser stripping at J-PARCSaha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.436 - 440, 2020/09
Nomura, Masahiro; Tamura, Fumihiko; Shimada, Taihei; Yamamoto, Masanobu; Furusawa, Masashi*; Sugiyama, Yasuyuki*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Yoshii, Masahito*
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.64 - 67, 2020/09
Image recognition using a convolutional neural network (CNN) has been used in a wide range of fields and has produced excellent results. If this image recognition technology is used effectively, it should be possible to obtain information from an image equal to or more than the information that a person can obtain from an image. At J-PARC, researchers with specialized knowledge obtain beam information needed to adjust the equipment from an image called mountain plot. In this study, we applied the image recognition technology by using CNN to this mountain plot image, and tried to obtain the information about the beam necessary for adjustment. As a result, we were able to obtain more information than is currently available by using the image recognition technology. In the future, we plan to adjust the equipment based on the information actually obtained from the image recognition technology and confirm its effectiveness
Matsuda, Makoto; Ishizaki, Nobuhiro; Tayama, Hidekazu; Kabumoto, Hiroshi; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; Abe, Shinichi; et al.
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.948 - 952, 2020/09
no abstracts in English
Tamura, Fumihiko; Yoshii, Masahito*; Kamikubota, Norihiko*; Takahashi, Hiroki
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.68 - 72, 2020/09
MTCA (MicroTCA) is expected to be the next generation platform for advanced control in accelerators. MTCA has many advantages over the widely used VMEs, such as high speed, large data transfer capacity, and high maintainability with hot-swappable modules. After the application to the LLRF control system at KEK, MTCA has been used in many accelerators around the world, while it takes a long time for MTCA to spread to the accelerators in Japan. Recently, the number of large-scale adoptions such as the LLRF control system, for the J-PARC RCS has been increasing. In this article, we introduce a case study of MTCA adoption and discuss why MTCA has not been widely used in Japan. Also, the efforts for the future promotion of MTCA in Japan are reported.
Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio; Nomura, Masahiro; Suganuma, Kazuaki; Fujirai, Kosuke; Kamiya, Junichiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Yoshimoto, Masahiro; et al.
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.209 - 213, 2020/09
The J-PARC 3GeV Rapid Cycling Synchrotron (RCS) is aiming to provide the proton beam of very high power for neutron experiments and the main ring synchrotron. We have continued the beam commissioning and the output power from RCS have been increasing. In recent years, just before the summer shutdown period, we have been trying continuous supply of 1-MW high-intensity beam, which is the design value, to a neutron target. First trial was 1-hour continuous operation in July 2018, and second trial was 10-hours continuous in July 2019. In both cases, we achieved almost stable operation. Furthermore, in June 2020, we tried to operate continuously for over 40 hours. But in this case, some trouble occurred and the operation was frequently suspended. Through these continuous operation trials, we have identified issues for stable operation of 1 MW. In this presentation, we will report the results of 1-MW continuous operation and issues obtained from these results.
Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Hasegawa, Katsushi*; Hara, Keigo*; et al.
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.674 - 678, 2020/09
Longitudinal beam simulation code BLonD (Beam Longitudinal Dynamics), which has been developed by CERN in recent years, is being used accelerator facilities around the world. BLonD can simulate longitudinal beam motion considering with wake voltage and space charge effect and is written by Python, which makes it highly readable and general-purpose code. We are currently conducting a benchmark of BLonD aiming at studying for further improvements of acceleration technology and stable operation of the J-PARC 3GeV synchrotron (RCS). The bunching factor, which express the longitudinal beam charge distribution, calculated by BLonD simulation reflected by the current 1MW beam operation parameters reproduce the experimental results well and the validity of BLonD for RCS longitudinal beam simulation was confirmed.
Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi; Oguri, Hidetomo
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.251 - 253, 2020/09
A bunch-shape monitor (BSM) in the low-energy region is being developed in the J-PARC linac to accelerate the high-intensity proton beam with the low emittance. A highly-oriented pyrolytic graphite (HOPG) was introduced as the target of the BSM to mitigate the thermal loading. The stable measurement of the BSM was realized thanks to the HOPG target, while the tungsten target was broken by the thermal loading from the high-intensity beam. However, since the longitudinal distribution measured with the BSM using the HOPG target was wider than the expected one, the improvement of tuning parameters is necessary for the BSM. The BSM consists of an electron multiplier, a bending magnet, and a radio-frequency deflector, which should be tuned appropriately. Behavior of these components were investigated and tuned. The longitudinal distribution measured with the BSM after the tuning was consistent with the expected one.
Kobayashi, Aine*; Toyama, Takeshi*; Shobuda, Yoshihiro; Nakamura, Takeshi*; Sato, Yoichi*
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.684 - 688, 2020/09
no abstracts in English
Toyama, Takeshi*; Kobayashi, Aine*; Nakamura, Takeshi*; Shobuda, Yoshihiro
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.689 - 692, 2020/09
no abstracts in English
Takayanagi, Tomohiro; Ono, Ayato; Horino, Koki*; Ueno, Tomoaki*; Togashi, Tomohito; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.25 - 28, 2020/09
We have been developing a semiconductor switch power supply to replace the RCS kicker power supply in J-PARC. A SiC MOSFET is used as a power semiconductor element, and a radially symmetric LTD circuit is used for the circuit board. The power supply consists of a combination of two types of circuit boards: a main circuit board, which includes the circuits of the thyratron, PFN and end clipper provided in RCS kicker power supplies, on a single module board, and a correction board, which compensates for flat-top droop. A single main circuit board can provide 800V/2kA output, and 52 main circuit boards and 20 correction boards have been used to successfully achieve the high voltage of 40kV and flat-top flatness of less than 
0.2%. Furthermore, a preliminary test of the dual-parallel circuit was conducted for a twin kicker power supply configuration, which is required for the RCS kicker power supply. The evaluation results and prospects are presented.
Fuwa, Yasuhiro; Ono, Ayato; Takayanagi, Tomohiro; Shinozaki, Shinichi; Mizobata, Satoshi*; Fang, Z.*
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.780 - 782, 2020/09
In the J-PARC linac, High Voltage DC power supplies (HVDC) to drive klystrons. These HVDCs are modulating-anode power supplies with a rated voltage of 110 kV and are operated by connecting up to four klystrons to a single HVDC. Since multiple klystrons are driven by a single HVDC, a voltage droop in the capacitor bank of the HVDC occurs in the beam pulse. This effect causes a decrease in the output power of the klystron. Half of the existing HVDC in J-PARC were installed at the J-PARC construction, and the other half were installed at the LINAC 400 MeV upgrade, and the capacitors show signs of age-related degradation. In the near future, the capacitors will be necessary to be replaced partially or completely. On the replacement of the capacitors, it will be necessary to re-evaluate the operating behavior of the HVDC when the capacitor bank configuration is changed. In this presentation, we evaluated the effect of the voltage droop on the klystron with the present configuration and the effect of changing the capacitor bank configuration with numerical and experimental results, and we discussed the countermeasure for the stable beam operation.
Ono, Ayato; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.590 - 593, 2020/09
At J-PARC, an ignitron is used for the clover 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, a semiconductor switch for ignitron substitution using a MOS gate thyristor is designed. In order to be used as a crowbar device, a switch capable of resisting an operating output of 120 kV, 40 kA, 50 us is required. We have realized an oval type substrate module that achieves an operating output of 3 kV, 40 kA, 50 us per substrate. It was possible to confirm the operating performance on a 1/10 scale (12 kV, 40 kA) against the voltage of the existing equipment (120 kV, 40 kA) by connecting four oval board modules in series. The output test result will be reported.
beam by electron beamOkabe, Kota
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.446 - 448, 2020/09
One of the important research themes for further enhancement of the proton accelerator is the advancement of the charge exchange injection method. At present, the charge exchange injection method in the high-intensity proton accelerator facility currently in operation mainly uses the charge exchange foil. However, this method has a problem in that activation of the around the charge exchange injection point due to beam scattering by the foil and neutrons generated from the foil. In order to solve this problem, new charge exchange injection methods such as laser charge exchange method are being researched in accelerator facilities around the world. In this research, we focus on the charge exchange method using electron beams and proceed with the basic experiments. In this presentation, we will report the progress of the charge exchange efficiency measurement of negative hydrogen ion beam using electron beam.
Takahashi, Hiroki; Sawabe, Yuki*; Watanabe, Kazuhiko*
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.275 - 279, 2020/09
The amount of monitor value (operation information) tends to increase, because of the increase of accelerator components, or in order to realize the safety and the stable operation. Then, an enormous volume of operation data increases the possibility of occurrence of erroneous operation such as overlooking of monitor value and etc. In order to ensure the safe and stable operation of the J-PARC accelerator, the occurrence of such human error is alarming. Therefore, for the purpose of operation support, we started designing and producing a system that monitors the machine status and detects alarm status from 2017. First, for Linac, we designed and produced a function to detect the alarm status based on the set value. Next, this function was applied to the machine status monitoring system for RCS. In addition, we are designing and developing functions to detect the alarm status based on the reference value or fixed value, for the purpose of detecting setting errors due to human error. In this paper, the current status and future plans of machine status monitoring system for J-PARC RCS are presented.
