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Nara, Yoshitaka*; Kashiwaya, Koki*; Oketani, Kazuki*; Fujii, Hirokazu*; Zhao, Y.*; Kato, Masaji*; Aoyagi, Kazuhei; Ozaki, Yusuke; Matsui, Hiroya; Kono, Masanori*
Zairyo, 73(3), p.220 - 225, 2024/03
The fractures in the rock are the main pass of groundwater flow and solute transport. The filling of fine-grained particle, such as clay minerals, was confirmed to decrease the permeability of rock by laboratory experiment. This research aimed to verify the occurance of the phoenomena in the fild. The water containing the clay minerals was injected into the rock at the 200m stage of the Mizunami undearground research laboratory. The hydraulic conductivity decreased two order before and after the injection. This result suggested that the decrease of hydraulic conductivity by the filling of fine-grained particle in the fractures occured in the real field.
Ono, Ayato; Takayanagi, Tomohiro; Fuwa, Yasuhiro; Shinozaki, Shinichi; Ueno, Tomoaki*; Horino, Koki*; Sugita, Moe; Yamamoto, Kazami; Kinsho, Michikazu; Ikoma, Naoya*; et al.
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.871 - 876, 2023/11
In J-PARC, an ignitron is used for the crowbar device of the klystron power supply to excite the RF acceleration voltage in a Linac cavity. Mercury, that is used in the ignitron, would be prohibition of use in the future due to environmental protection. 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 3kV, 40kA, and 50us per board. Because a high voltage of 120 kV is applied on each board, we adopted a self-power supply method to supply a electricity for the control system. This method can create the electricity from a high-voltage DCDC converter. We confirmed the operating performance on a 1/2 scale (60 kV, 40 kA) of the voltage in the existing ignitron system (120 kV, 40 kA). We also studied a test circuit in a higher voltage range of more than 90 kV. Our latest result is well promising for an alternative system of ignitron.
Sugita, Moe; Takayanagi, Tomohiro; Ueno, Tomoaki*; Ono, Ayato; Horino, Koki*; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.519 - 522, 2023/11
In J-PARC RCS, paint bump magnets are used to displace the beam orbit during paint injection, which produces a high intensity beam. A pattern of command current and command voltage can be used to create an output current waveform that varies the beam orbit over time. The accuracy of beam orbit control is determined by the shape difference between the command current and output current waveforms. In the current paint pattern adjustment, a deviation of 
1% or less is achieved by manual adjustment after using software that adjusts the pattern according to the response function of the power supply control. However, we would like to reduce the adjustment time. In addition, since the accuracy of paint injection is determined by the adjustment system of the paint magnet power supply, we would like to achieve output current deviation 10 times more precise than before to reduce beam loss. An analytical model of the load-side impedance is necessary to create a high-precision paint pattern, but it is very difficult to construct an analytical model because the load-side impedance changes in a time-varying nonlinear paint pattern. We used machine learning to adjust the output pattern of the paint pattern and achieved a deviation of less than 0.5% through repeated learning. This presentation will report on the current status of the system and its prospects.
Ono, Ayato; Takayanagi, Tomohiro; Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
JAEA-Technology 2022-036, 31 Pages, 2023/03
JAEA-Technology-2022-036.pdf:8.77MB
In the Japan Atomic Energy Agency (JAEA), many electrical facilities such as power receiving equipment and power supply units are installed in experimental facilities such as the Nuclear Science Research Institute (NSRI) and the Japan Proton Accelerator Research Complex (J-PARC). However, some facilities have been in operation for more than half a century since they were manufactured, some have already been closed or deactivated, and others are still in operation while replacing parts and taking other aging measures. In these facilities, materials that were used because of their excellent properties at the time of manufacture are now designated as hazardous substances and require special management when disposed of. One of them is polychlorinated biphenyl (PCB). PCB were used in a very wide range of fields because of their stability against heat, high electrical insulation, and chemical resistance. However, it was found that PCB have persistent properties and may cause damage to human health and the living environment, and the government has enacted the "Act on Special Measures for Promotion of Proper Treatment of PCB Wastes (PCB Special Measures Law)" to promote reliable and proper disposal. JAEA has almost completed the excavation survey of high-concentration PCB waste and is in the process of excavating low-concentration PCB waste. However, there are still new relevant items to be discovered. This report summarizes and reports the knowledge necessary for identifying PCB waste and points to be noted when handling capacitors, etc., based on examples of actual disassembly and investigation work conducted on power supply units and other electrical equipment, such as capacitors attached to power supply units, etc.
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.
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.
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; Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Ono, Ayato; Yamamoto, Kazami; Kinsho, Michikazu
IEEE Transactions on Applied Superconductivity, 32(6), p.4101405_1 - 4101405_5, 2022/09
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)In order to design a pulsed electromagnet, it is necessary to consider eddy currents that depend on the pattern shape of the pulse excitation, and to design the structure and set the operating parameters considering the fluctuation of the magnetic field distribution and its effect on heat generation. Evaluation tests of a new bump magnet for the J-PARC RCS showed that the magnetic field distributions at the rising edge of the trapezoidal pattern and at the flat top are different from each other. This was also confirmed by the 3D dynamic magnetic field analysis of OPERA-3d. Since the skin-depth due to eddy currents depends on the time variation of the waveform, the effect is the same as changing the shape of the coil. The measurement of the magnetic field distribution fluctuation was verified and evaluated using a flux meter, search coil, and Hall probe with different measurement principles.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
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.
Ono, Koki*; Higomoto, Toshiya*; Saito, Yugo*; Uchino, Shun; Nishida, Yusuke*; Takahashi, Yoshiro*
Nature Communications (Internet), 12, p.6724_1 - 6724_8, 2021/11
Times Cited Count：8 Percentile：69.3(Multidisciplinary Sciences)Quantum transport is ubiquitous in physics. So far, quantum transport between terminals has been extensively studied in solid state systems from the fundamental point of views such as the quantized conductance to the applications to quantum devices. Recent works have demonstrated a cold-atom analog of a mesoscopic conductor by engineering a narrow conducting channel with optical potentials, which opens the door for a wealth of research of atomtronics emulating mesoscopic electronic devices and beyond. Here we realize an alternative scheme of the quantum transport experiment with ytterbium atoms in a two-orbital optical lattice system. Our system consists of a multi-component Fermi gas and a localized impurity, where the current can be created in the spin space by introducing the spin-dependent interaction with the impurity. We demonstrate a rich variety of localized-impurity-induced quantum transports, which paves the way for atomtronics exploiting spin degrees of freedom.
MnGa thin films underneath a protection layerKono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki; Muro, Takayuki*; Goto, Kazuki*; Sakuraba, Yuya*; Umetsu, Rie*; Kimura, Akio*
Physical Review B, 104(19), p.195112_1 - 195112_8, 2021/11
Times Cited Count：4 Percentile：36.85(Materials Science, Multidisciplinary)Angle-resolved photoelectron spectroscopy utilizing soft X-ray synchrotron radiation was applied to Heusler-type CoMnGa thin films that have a 1-nm Al capping layer. The bulk Fermi surfaces and band structures varied along the out-of-plane momentum, stemming from the three-dimensional crystal structure, in the absence of any in situ surface treatment. In addition, there were characteristic intersecting bands (Weyl cones), with crossing points near the Fermi level, which were consistent with computed results. The Weyl cones are of bulk origin and are responsible for the high anomalous Nernst and the anomalous Hall coefficients. A close comparison of the experimental band structures in CoMnGe and CoMnGa indicated that the rigid band picture is valid in both alloys and that fine carrier tuning is possible by replacing Ga with Ge to improve the anomalous conductivity.
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 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.
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 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.
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 
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.
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.
Takayanagi, Tomohiro; Ono, Ayato; Ueno, Tomoaki*; Horino, Koki*; Togashi, Tomohito; Yamamoto, Kazami; Kinsho, Michikazu; Koizumi, Isao*; Kawamata, Shunsuke*
JPS Conference Proceedings (Internet), 33, p.011020_1 - 011020_6, 2021/03
We are developing a new kicker power supply for J-PARC 3-GeV RCS (Rapid-Cycling Synchrotron) using the next generation power semiconductor SiC-MOSFET with high withstand voltage, low loss, and superior high frequency characteristics. The three major circuits adopted for the RCS kicker power supply, the thyratron switch, the PFN circuit of coaxial cable type, and the end clipper for reflection wave absorption, has been realized with a single modular circuit board based on the LTD circuit. The new kicker power supply realizes stable operation, miniaturization and energy saving by using power semiconductors. The required high voltage can be output by stacking the 800V/2kA modular circuit board in series. The details of circuit design and the results of achieving an output of half 20kV/2kA against the target specification of 40kV/2kA are presented here.
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.
Sumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.
Communications Materials (Internet), 1, p.89_1 - 89_9, 2020/11
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.
