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Shobuda, Yoshihiro; Harada, Hiroyuki; Saha, P. K.; Takayanagi, Tomohiro; Tamura, Fumihiko; Togashi, Tomohito; Watanabe, Yasuhiro; Yamamoto, Kazami; Yamamoto, Masanobu
Physical Review Accelerators and Beams (Internet), 26(5), p.053501_1 - 053501_45, 2023/05
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)At the Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC), theoretical predictions have indicated that the kicker-impedance would excite the beam-instability. A 1 MW beam with large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) through suppression of the beam instabilities by choosing the appropriate machine parameters. However, we require other high-intensity and high-quality smaller emittance beams (than the 1 MW beam) for the Main Ring (MR). Hence, we proposed a scheme for suppressing the kicker-impedance by using prototype diodes and resistors, thereby demonstrating the effect on the kicker impedance reduction. However, the J-PARC RCS must be operated with a repetition rate of 25 Hz, which urged us to consider special diodes that are tolerant to heating. After developments, we have demonstrated that the special diodes with resistors can suppress the beam instability by reducing the kicker impedance. Enhanced durability of the prototype diodes and resistors for the 25 Hz operation was also realized. Moreover, the new diodes and the resistors have negligible effect on the extracted beam from the RCS. From a simulation point of view, the scheme can be employed for at least 5 MW beam operation within the stipulated specifications.
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.
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.
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.
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.
Shobuda, Yoshihiro; Irie, Yoshiro*; Takayanagi, Tomohiro; Togashi, Tomohito; Yamamoto, Masanobu; Yamamoto, Kazami
Journal of Physics; Conference Series, 1067, p.062007_1 - 062007_8, 2018/10
Times Cited Count：2 Percentile：68.25(Physics, Particles & Fields)The present four-terminal kicker at the Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) has the power-saving benefit due to the doubled excitation currents by shorting two-terminals. On the other hand, beam instabilities are excited by the kicker impedances. In this report, we describe a scheme to reduce the kicker impedances using diodes (nonlinear devices) with resistors, while retaining the benefit of the doubled kicker excitation currents.
Shobuda, Yoshihiro; Chin, Y. H.*; Hayashi, Naoki; Irie, Yoshiro*; Takayanagi, Tomohiro; Togashi, Tomohito; Toyama, Takeshi*; Yamamoto, Kazami; Yamamoto, Masanobu
Physical Review Accelerators and Beams (Internet), 21(6), p.061003_1 - 161003_15, 2018/06
Times Cited Count：4 Percentile：36.29(Physics, Nuclear)no abstracts in English
Shobuda, Yoshihiro; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Takayanagi, Tomohiro; Tamura, Fumihiko; Tani, Norio; Togashi, Tomohito; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2946 - 2949, 2017/05
no abstracts in English
Togashi, Tomohito; Takayanagi, Tomohiro; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.725 - 728, 2016/11
The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) has the pulse kicker power supply system which use the thyratron switches for beam extraction. It has passed from operation starting for more than 10 years, but an exchange of a part and check are being put into effect periodically, so a kicker power supply also keeps operation smoothly now. I spent long time and studied how to use, so thyratron could be used now for more than 10,000 hours. But long years have passed, so selection of a substitute of a discontinuance part is a pending problem. Silicon oil has also degraded, so I have to consider a way of a performance recovery and a procedure of an exchange. This report explains the current state of the kicker magnet power supply from a result of the regular inspection and conditions.
Takayanagi, Tomohiro; Ueno, Tomoaki; Horino, Koki; Togashi, Tomohito; Tobita, Norimitsu*; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.699 - 702, 2016/11
no abstracts in English
Suganuma, Kazuaki; Togashi, Tomohito; Watanabe, Masao; Kinsho, Michikazu
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.678 - 680, 2014/07
Technical issues of the kicker magnet system in the J-PARC 3GeV RCS are presented based on the operating experience during four years. For the high voltage cables, many scratches on the polyethylene surface were observed at the edge parts, the surfaces were reinforced by a semi-conductive layer with high-dielectric materials. For all matching resisters, the values have been increased due to deterioration with age, and the counter measure is under reviewing. For Thyratron tubes, a stable operation was established, and the beam stop rate by false operation was drastically reduced from 13% to less than 0.5%.
Hayashi, Naoki; Harada, Hiroyuki; Horino, Koki; Hotchi, Hideaki; Kamiya, Junichiro; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; et al.
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3833 - 3835, 2014/07
no abstracts in English
Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki; Horino, Koki; Togashi, Tomohito; Kinsho, Michikazu; Watanabe, Yasuhiro; Irie, Yoshiro*
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.681 - 683, 2014/07
The power supply of the pulse steering magnet has been produced. The power supply has the equipment used to excite the pulse current and the direct-current (DC) to correspond to two modes that the painting injection for beam users and the central injection for beam commissioning. The pulse current has been performed with good accuracy whose deviation to a setting current becomes to be less than 0.2%. In case of the central injection, the power supply excites the current in DC mode, which has been realized the ripple current below 0.01%. This paper describes the design parameters and the experimental results of the power supply.
Tani, Norio; Takayanagi, Tomohiro; Ueno, Tomoaki; Harada, Hiroyuki; Saha, P. K.; Togashi, Tomohito; Horino, Koki; Hayashi, Naoki
IEEE Transactions on Applied Superconductivity, 24(3), p.0504004_1 - 0504004_4, 2014/06
Times Cited Count：5 Percentile：31.61(Engineering, Electrical & Electronic)J-PARC RCS has two functions as a proton beam driver to the spallation neutron source at MLF and also as an injector to MR. However the required beam parameters for each facility are different. The pulse steering magnet (PSTR) was developed to satisfy these requirements by switching the painting area in each acceleration cycle of MLF and MR and to realize center injection at 400 MeV. Therefore there are two operation modes, painting injection and center injection, for operation of PSTR. Painting injection switches beam size (emittance) between MR and MLF and center injection sets injected beam in the same phase space position. The former is operated with pulse mode of trapezoid current pattern and the latter is realized in DC mode. The magnet field measurement was also performed with two operation modes. In this paper we will report the result of the field measurement of PSTR.
Takayanagi, Tomohiro; Ueno, Tomoaki; Horino, Koki; Togashi, Tomohito; Hayashi, Naoki; Kinsho, Michikazu; Irie, Yoshiro*
IEEE Transactions on Applied Superconductivity, 24(3), p.3800905_1 - 3800905_5, 2014/06
Times Cited Count：4 Percentile：27.1(Engineering, Electrical & Electronic)Each pulse power supply of the bending magnets at the J-PARC 3-GeV RCS injection area has been designed and manufactured for the painting injection in the transverse plane. The shift bump and pulse steering magnets generate a trapezoidal waveform, the flat-top part of which is used for beam injection. The horizontal and vertical painting bump magnets dynamically change the beam orbit using a decaying waveform. The PFN switching capacitor system does not produce a current ripple at the flat top, although the IGBT chopping system cannot be free from ripple generation due to switching. However, the IGBT chopping system has an advantage of producing an arbitrary wave pattern as required. This paper summarizes the comparison of both power supply system from view point of the circuit structure, the switching noise and the control of the wave pattern formation.
Takayanagi, Tomohiro; Hayashi, Naoki; Kinsho, Michikazu; Ueno, Tomoaki; Togashi, Tomohito; Horino, Koki; Irie, Yoshiro*
IEEE Transactions on Applied Superconductivity, 24(3), p.0503504_1 - 0503504_4, 2014/06
Times Cited Count：6 Percentile：35.68(Engineering, Electrical & Electronic)New power supply of the injection shift bump magnet at the J-PARC 3-GeV RCS has been designed with the energy upgrading of LINAC to 400 MeV. The power supply is required to output the maximum current of 32 kA, which is 1.6 times the present current. Moreover, both current ripple noise and deviation should be less than 0.2% in a range from 10 kA to 32 kA output current. The IGBT chopping system as in the present power supply occurs the continuous current ripple due to the switching. So the circuit structure of the power supply has been changed from the IGBT chopping system to the PFN system by switching the capacitors. The power panel is comprised of 16 banks, each of which outputs 2 kA at 14 kV at maximum. More than four banks have been manufactured and the characteristics were evaluated in the factory. This paper summarizes the design and the experimental results of the new power supply.
Suganuma, Kazuaki; Togashi, Tomohito; Kinsho, Michikazu
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.870 - 872, 2014/06
We started the initial tests of thyratron CX2004X at the switching test stand of the J-PARC. Deuteron gauss of this model is about 2 times as much as CX1193C one, by employing two reservoir tanks. A log life time more than thyratron CX1193C could be expected.
Saha, P. K.; Harada, Hiroyuki; Hayashi, Naoki; Horino, Koki; Hotchi, Hideaki; Kinsho, Michikazu; Takayanagi, Tomohiro; Tani, Norio; Togashi, Tomohito; Ueno, Tomoaki; et al.
Physical Review Special Topics; Accelerators and Beams, 16(12), p.120102_1 - 120102_11, 2013/12
Times Cited Count：4 Percentile：33.02(Physics, Nuclear)Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro; Kinsho, Michikazu
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.471 - 473, 2012/08
The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) uses 8 pulse kicker magnets for the beam extraction at a repetition rate of 25 Hz. Each kicker power supply has 2 thyratrons and thus they are 16 in total. An average life time of thyratrons even more than the J-PARC annual operation time of 5000 hours and a stable operation with a downtime of less than only 0.5% has already been achieved. The present maintenance procedures and statistics for the long term operation with thyratrons are reported in this paper.
Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki; Togashi, Tomohito; Irie, Yoshiro*
IEEE Transactions on Applied Superconductivity, 22(3), p.5400704_1 - 5400704_4, 2012/06
Times Cited Count：4 Percentile：29.2(Engineering, Electrical & Electronic)The simulation model for a new power supply of the injection bump system magnets of the 3-GeV RCS in J-PARC has been constructed. The new power supply requires the reduction of the ripple noise current which will resonate with load and excites a forced beam oscillation at the injection stage. In order to incorporate the load impedance in the simulation model, the impedances of a feeder line and the bump magnet with a ceramic vacuum chamber inside were measured. The RF shield is formed on the ceramic surface along the beam direction. The results were analyzed using the OPERA-3D and the circuit simulation code, Micro-Cap. A good agreement with measured was obtained.
