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Nakanoya, Takamitsu; Yoshimoto, Masahiro; Saha, P. K.; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.937 - 941, 2023/11
In the J-PARC 3GeV Rapid Cycling Synchrotron (RCS), the 400MeV H
beam is changed to H+ beam by a charge exchange foil and accelerated to 3GeV. So far, RCS had used two types of charge exchange foil. One is the HBC (Hybrid Boron mixed Carbon) foil and the other is the Kaneka GTF (Graphene Thin Film). HBC foil is a patented deposition method developed at KEK for the stable production of thick carbon foil. Initially, the RCS used HBC foil produced atKEK. However, in 2017, JAEA had started HBC foil production and has been using it since then. Recently, we have succeeded in depositing thick pure carbon foil, which had been considered difficult to produce by the arc deposition method. As a new challenge, this pure carbon foil was used in the user operation from March 2023. As a result, Pure carbon foils showed less deformation and more stable charge exchange performance than HBC and GTF.
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.
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; Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
JAEA-Technology 2021-044, 53 Pages, 2022/03
JAEA-Technology-2021-044.pdf:43.7MB
The 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex (J-PARC) uses a large number of electromagnet power supplies in order to manipulate a high-intensity beam of 1 MW. These devices have been specially developed to meet the requirement to achieve acceleration of the 1-MW proton beams. Because J-PARC has been in operation for 10 years, we have to replace many parts and equipments due to failures caused by age-related deterioration. J-PARC accelerator system supplies the beams for many users, and we have to recover it as soon as possible when a trouble occurs. Therefore, if the trouble can be prevented before it happens, reduction of the user beam time can be minimized. Furthermore, it enables us to reduce additional work for operators. Maintenance is important to keep the equipments in a normal state, and makes it possible to extend the life of the equipments by detecting and maintaining the faulty parts and the aged deterioration parts at an early stage. Since all the devices requires the maintenance, there are a wide variety of maintenance methods. Some works are carried out by the J-PARC members, and some are performed by outsourcing. Ensuring safety and protecting workers are the most important issues in maintenance work. Therefore, J-PARC has rules for safety work. All workers in J-PARC have to learn and follow the rules. In addition, various ideas are being considered to enable safe and efficient work by devising ingenuity in each work. We also elaborate various ideas and processes for safe and efficient work according to the individual work conditions. In this report, we summarize the guideline and cautionary points during maintenance based on the actual case of maintenance and inspection work of the horizontal shift bump electromagnet power supply.
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.
Ono, Ayato; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
JAEA-Technology 2021-005, 40 Pages, 2021/05
JAEA-Technology-2021-005.pdf:4.27MB
The 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex (J-PARC) uses a large number of electromagnet power supplies in order to manipulate a high-intensity beam of 1 MW. These devices have been specially developed to meet the requirement to achieve acceleration of the 1-MW proton beams. State-of-the-art technologies are used to these devices. To achieve stable operation with few failures, and to prevent major troubles in the event of a failure, it is necessary to maintain the performance of the devices under the appropriate and accurate management strategy with an enough understanding of its characteristics. However, since the specification and function of each device is different respectively, and it is also produced by different manufacturer, we have to maintain adequately according to the structure, configuration and features of the apparatus. There are typically three major stages in the maintenance works. First, "Daily inspection" is constantly performed to monitor the status of the equipment during operation and check for any errors or abnormalities. Second, "Routine maintenance" is carried out weekly, monthly, or yearly to fix the errors, or to replace the parts that are deteriorated. Third, "Troubleshooting" is conducted to recover from sudden failures. In this report, we will introduce the specific contents of "Routine maintenance", "Daily inspection", and "trouble case" based on the experiences of the electromagnet power supply group. In particular, we will report the work management methods, including ideas for facilitating recovery work. We will also summarize the important points of a matter that does not depend on the configuration, structure, and characteristics of the equipment.
Ono, Ayato; Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
JAEA-Technology 2020-023, 40 Pages, 2021/02
JAEA-Technology-2020-023.pdf:2.98MB
The 3 GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex (J-PARC) uses a large number of electromagnet power supplies in order to generate a high-intensity beam of 1 MW. These devices have been specially developed to meet the required specifications of the proton beams. Ten years have passed since the 3 GeV synchrotron had started operation, and we need to replace and update of the components due to failures caused by the aging deterioration. Since the J-PARC is used by many users, it is quite important to recover as soon as possible when a trouble occurs. However, we often spend lots of time to investigate the status and cause of the problem, then it results in the delay of recovery work. One of the major reasons is due to the differences in the manufacturers of sensors and monitors. Therefore, we have to create a manual for each power supply and prepare some exclusive tools. However, troubles rarely occur in the same state and situation, so we have to rely on the experience and knowledge. Even for power supplies with different purposes and specifications, some components, such as sensors, can be shared in many cases. In addition, if the concept of the interlock system, for monitoring the status of the power supply and detecting malfunctions, is shared between the different power supplies, the method and response for failure investigation can be standardized. By using a device with good maintainability, the accelerator operation will be more stable and reliable. In this report, we introduce the necessity of sharing the design concept and common parts. We also explain the basic design model for safety and reliability, using an example of manufacturing an electromagnet power supply for the 3 GeV synchrotron.
Yamamoto, Kazami; Saha, P. K.
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1045 - 1047, 2018/06
The 3 GeV rapid cycling synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have conducted a beam study to achieve high-power operation. In addition, we have also maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last two years.
Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*
Progress of Theoretical and Experimental Physics (Internet), 2017(11), p.113G01_1 - 113G01_24, 2017/11
Times Cited Count：2 Percentile：21(Physics, Multidisciplinary)Two proton bunches circulates the accelerator ring in the J-PARC 3GeV synchrotoron (RCS). The accelerating voltage is also generated in twice of the revolution frequency. The major Fourier component of the wake voltage should become even harmonics. However, the odd harmonics grow and cause a large number of beam loss. The beam measurement suggests that the odd harmonic wake voltages promote oscillations of not only the bunch position but also the bunch shape. The oscillations continue because they amplify the odd harmonic beam components. A particle tracking simulation can reproduce these simultaneous oscillations. It is found that the odd harmonic wake voltages lead to severe rf bucket distortion that results in beam loss. As a result, introducing a beam loading compensation system for the minor harmonics can prevent the beam loss and it would contribute the stable accelerator operation with the reduction of the activation.
Yoshimoto, Masahiro; Harada, Hiroyuki; Okabe, Kota; Kinsho, Michikazu
Proceedings of 4th International Beam Instrumentation Conference (IBIC 2015) (Internet), p.575 - 579, 2016/01
In the J-PARC RCS, transverse beam profiles including both the beam core and halo at extraction beam transport line (3NBT) were measured by using a combination with a wire scanner type beam scraper and some beam loss monitors (BLMs). Our final goal of this halo monitor is to measure the intra-bunch beam halo of extracted two bunches from the RCS. Thus the plastic scintillator and photomultiplier (PMT) assemblages were adopted as the BLMs with quick time response. However, we found that the BLMs detected not only the radiation from the wire but also reflected one from other devices and wall. Therefore we tried to develop new-type BLMs, which are scintillation-type BLM of lead glass and Cherenkov-type BLM of quartz or UV acrylic. In this presentation, we will report on the overview and experimental results of the new-type BLMs together with the outline of halo monitor system.
Yamamoto, Masanobu; Hara, Keigo*; Hasegawa, Katsushi*; Nomura, Masahiro; Omori, Chihiro*; Shimada, Taihei; Tamura, Fumihiko; Toda, Makoto*; Yoshii, Masahito*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1008 - 1012, 2015/09
A harmonic number of J-PARC RCS is two, and when all RF buckets are filled with bunches, the major parts of the beam Fourier components are the even harmonics. However, the particle tracking simulation suggests that the odd harmonics promote asymmetry on each bunch shape and they rapidly increase under some conditions. When the asymmetry becomes larger and larger monotonously, it causes severe beam loss. Furthermore, although the odd harmonics remain small amplitude, an amplitude modulation of them makes a beam halo and causes small beam loss. We describe the particle tracking simulation results to investigate the odd harmonics.
Yoshimoto, Masahiro; Harada, Hiroyuki; Hotchi, Hideaki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Kinsho, Michikazu
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.944 - 946, 2015/06
In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode. By tuning the tank level of the debuncher 2 in the LINAC, it can be measured the momentum spread was shifted from 0.06% to 0.15%. Moreover, these distributions of the momentum spread are consistent with the simulation results.
Kinsho, Michikazu
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.3798 - 3800, 2015/06
Beam power of routine operation of the J-PARC rapid cycling synchrotron (RCS) increased gradually for the MLF user operation, beam power of 400 kW was achieved on 10th March, and 500 kW user operation has been stably performed from 14th April this year. Beam studies were also performed to demonstrate the capability of the RCS to operate at powers in excess of 1 MW. The study produced a beam intensity of 8.41
10
protons during short time, an intensity equivalent to 1.01 MW operation on 10th January 2015. In this beam study it was cleared issues to realize 1MW operation in the RCS. Status of user operation and issues to realize high power operation in the RCS are presented.
Hotchi, Hideaki
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.6 - 11, 2015/03
The J-PARC 3-GeV Rapid Cycling Synchrotron (RCS) is the world's highest class of high-power pulsed proton driver aiming at 1-MW output beam power. In the last summer shutdown of 2013, the injection energy from the linac was upgraded from 181 MeV to the design value of 400 MeV. In addition, in this summer shutdown of 2014, the maximum peak current of the injection beam was increased from 30 mA to the design value of 50 mA. In October 2014 after completing these series of the injector linac upgrades, we have started the final stage of beam tuning toward the design output beam power of 1 MW. The most important issues in realizing such a high power 1 MW beam operation are control and minimization of beam loss. This talk will present our approaches to beam loss issues that we faced on the process of the beam power ramp-up.
Yoshimoto, Masahiro; Harada, Hiroyuki; Okabe, Kota; Kinsho, Michikazu
Proceedings of 54th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams (HB 2014) (Internet), p.143 - 147, 2015/03
Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. In the beam profile, there are the beam core which is a high density area, the beam tail which is a low density area around the beam core, and the beam halo which is the area outside of the beam tail and in which few particles are straggling. Generally, the beam halo intensity is less than 1/100000 
1/1000000 of the beam core. Therefore, the dynamic range of the beam halo is required typically an order of 10
, but it is difficult to achieve this ultra wide dynamic range by any one diagnostics. Then, new beam halo monitor, which is combined a wire type beam scraper and some beam loss monitors, are developed and installed in the extraction beam transport line. Each beam loss monitor has not more than 10
order of the dynamic range. However, to use some beam loss monitors with a plurality of different sensitivity range, its ultra wide dynamic range can be achieved and beam profile including both of the beam core, beam tail, and beam halo can be obtained.
Saha, P. K.; Shobuda, Yoshihiro; Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Tamura, Fumihiko; Yamamoto, Masanobu
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1683 - 1685, 2014/07
Kinsho, Michikazu; Saito, Yoshio*; Kabeya, Zenzaburo*; Ogiwara, Norio
Vacuum, 81(6), p.808 - 811, 2007/02
Times Cited Count：7 Percentile：30.05(Materials Science, Multidisciplinary)It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section of 378 mm inner diamater for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. The radio-frequency shield is designed as a high frequency pass filter, where eddy currents cannot be generated. In this shield one end of each strope is connected to a titanium flange with a capacitor to interrupt the eddy current loop. With this, the impedance of the duct with the radio-frequency shield was reduced within an allowable desgin limit. In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.
Watanabe, Masao; Irie, Yoshiro; Kamiya, Junichiro; Shimada, Taihei; Takayanagi, Tomohiro; Suzuki, Hiromitsu; Watanabe, Yasuhiro; Kawakubo, Toshimichi*
IEEE Transactions on Applied Superconductivity, 16(2), p.1354 - 1357, 2006/06
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)Septum magnets used in the injection and extraction section of the 3 GeV rapid cycling synchrotron of the J-PARC require large aperture for low-loss operations of high intensity beam, protection against the high radiation and the high durability to avoid the maintenance after the high activation. A prototype septum magnet was constructed. Magnetic fields in the gap of the core and leakage field outside of the magnetic shield were measured by a Hall device probe. The experimental results were compared with the 3D calculation by TOSCA. The leakage field of the measurements is larger than the one of the model. After we made a more detailed model, it cleared that many bolt holes which fasten a return yoke narrow the effective sectional area and thus reduce the permeability at the return yoke, making the leakage field larger. Because the thickness of the return yoke is not sufficient, magnetic flux density approaches saturation easily. Moreover, we discuss about the results of heat measurements of the magnet and efficiency of water cooling.
Watanabe, Masao; Irie, Yoshiro; Kamiya, Junichiro; Shimada, Taihei; Takayanagi, Tomohiro; Fujimori, Hiroshi*; Igarashi, Susumu*; Kawakubo, Toshimichi*; Nakayama, Hisayoshi*
IEEE Transactions on Applied Superconductivity, 16(2), p.1350 - 1353, 2006/06
Times Cited Count：2 Percentile：18.87(Engineering, Electrical & Electronic)Thick septa are used in the injection and extraction section of the 3 GeV rapid cycling synchrotron of the J-PARC. We have been designing seven thick septum magnets, two for injection, two for beam dump and three for extraction, respectively. These septa require low-loss operations. For the mechanical stability they are operated by direct current. The yoke is made of the soft-iron block. We have been designing them by using the three-dimensional magnet static field calculation code, TOSCA. In this presentation, we discuss about magnetic field flatness in the gap and effects of the leakage fields in the synchrotron.
