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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/1.2
s 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; 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.
Takayanagi, Tomohiro; Ueno, Tomoaki; Horino, Koki
Journal of Physics; Conference Series, 1350(1), p.012183_1 - 012183_7, 2019/12
Times Cited Count：0 Percentile：0.06(Physics, Particles & Fields)As one of the advanced research and development for maintaining the stable operation of J-PARC RCS, we are developing semiconductor switch circuit for thyratron substitute adopted in kicker system. Radiation symmetric type circuits using semiconductors of SIC-MOSFETs are composed of circuits in which many semiconductor switches are multiplexed in parallel. Since the lengths of all parallel circuits are equal, the output waveform will not be distorted due to timing jitter or impedance. This circuit is useful for outputting the waveform of ultrafast short pulse. Therefore, we have developed a circuit that achieves further low inductance by making the power transmission circuit into a double circular ring structure equal to the coaxial shape. Compare the inductance value obtained from the structure and the output waveform. In addition, we compare the calculation and the measurement in the test and present the verification result of the developed circular ring structure.
Takayanagi, Tomohiro; Ono, Ayato; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.75 - 79, 2019/07
We will replace the Thyratron and Ignitron discharge type switch with a semiconductor switch capable of more stable operation. The thyratron alternative switch used by the kicker power supply manufactured the radial symmetric module substrate of the 800V/2kA output which was built by LTD circuit using SiC-MOSFET. By making the power transfer structure between module substrates stacked for high voltage output into a coaxial ring type, a further reduction in inductance is realized. We report the results of evaluating a pulse output of 20kV/1kA (final specification is 40kV/2kA). Ignitron, which is used as a high-power klystron clover switch, has the potential to be discontinued in the future because it uses mercury, which has limited use worldwide. LINAC's klystron clover switches require a working output of 50kV at 120kV/40kA. We fabricated 3kV/40kA oval type module substrate using MOS gate thyristor. Report on preliminary test results.
Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.244 - 248, 2018/08
We will present the development of super high voltage short pulse switch power supply aiming at high performance of 3 GeV synchrotron accelerator pulsed electromagnet power supply. We are developing the switch power supply using SiC-MOSFET of the next generation power semiconductor which is higher in breakdown voltage, lower loss, and higher frequency operation than the current mainstream Si power semiconductors. The SiC conversion of semiconductors enables commercialization of thyratron substitute switches and power-saving small size switching power supplies. However, products that satisfy the specification of the thyratron (80kV/4kA) adopted for the J-PARC 3 GeV-RCS kicker power supply with one module have not been developed. Therefore, it is necessary to construct a circuit in which power semiconductors are multiplexed in series and parallel. In addition, the high-speed short pulse waveform required for the kicker power supply is designed with consideration of the circuit impedance such as inductance and stray capacitance separately from the performance improvement of the power semiconductor. Therefore, a circular radially symmetric circuit was constructed in which power semiconductors were concentrically arranged and the impedance of all parallel circuits could be made equal. As a result, waveform distortion caused by the difference in circuit impedance could be suppressed. This structure is adopted in the LTD circuit and it is indispensable for the development of semiconductor new kicker power supply. In this presentation, the results of the preliminary test and the evaluating test are reported.
Yokoseki, Takashi; Abe, Hiroshi; Makino, Takahiro; Onoda, Shinobu; Tanaka, Yuki*; Kandori, Mikio*; Yoshie, Toru*; Hijikata, Yasuto*; Oshima, Takeshi
Materials Science Forum, 821-823, p.705 - 708, 2015/07
Mizuta, Eiichi*; Kuboyama, Satoshi*; Abe, Hiroshi; Iwata, Yoshiyuki*; Tamura, Takashi*
IEEE Transactions on Nuclear Science, 61(4), p.1924 - 1928, 2014/08
Times Cited Count：95 Percentile：99.19(Engineering, Electrical & Electronic)Oshima, Takeshi
Hoshasen To Sangyo, (105), p.12 - 18, 2005/03
no abstracts in English
Laube, M.*; Pensl, G.*; Lee, K. K.; Oshima, Takeshi
Materials Science Forum, 457-460, p.1381 - 1384, 2004/10
The electrical properties of n-channel 6H-SiC MOSFETs have been studied by temperature-dependent current-voltage and Hall effect measurements. The MOS transistors are either wet (sample A) or dry oxidized followed by a post-annealing step at 1100
C and a pyrogenic reoxidation at 800C (sample B). Higher drain transconductance and saturation currents are observed in sample B. The Hall effect investigations show that this improvement in the performance of the MOS transistors (sample B) is caused by a lower degree of trapping of free electrons. The density of interface traps D
close to the conduction band edge has been determined from the shift of the threshold voltage V
as a function of the temperature and from the Hall effect results. D is about two times lower in sample B. The room temperature value of the electron Hall mobility is determined to be about 60 cm
/Vs for both samples; it increases with decreasing temperature.
-ray irradiationOshima, Takeshi; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.191 - 194, 2004/10
no abstracts in English
Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro
Materials Science Forum, 457-460(Part2), p.1405 - 1408, 2004/06
The electrical characteristics of cubic silicon carbide (3C-SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with the current direction in the inversion layer perpendicular to [-110] ([-110]-perpendicular MOSFETs) were compared to those of 3C-SiC MOSFETs with the current direction in the inversion layer parallel to [-110] ([-110]-parallel MOSFETs). The threshold voltage (V
) for both MOSFETs shows -0.5 V although enhancement type MOSFETs were designed. The values of channel mobility which was estimated from linear region of drain current (I
) - drain voltage (V) curves are 230 cm/Vs for [-110]-perpendicular MOSFETs and 215 cm/Vs for [-110]-parallel MOSFETs, indicating no significant difference between both MOSFETs. The value of I for [-110]-perpendicular MOSFETs is of order of 10-8 A at V = 10V and gate voltage (V
) of -2V. However, for [-110]-parallel MOSFETs, I shows of order of -10-6 A at V = 10V and V = -2V.
Lee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
Materials Science Forum, 433-436, p.761 - 764, 2003/08
The possibility of applying p-channel SiC MOSFET to dosimeter was investigated. The Source and Drain of SiC MOSFET was formed Al ion implantation at 800 
C and annealing at 1800 C for 1 min in Ar. The gate oxide was fabricated using pyrogenic oxidation. Al electrodes of source and drain is formed Al evaporation and sintering at 850 C for 5 min in Ar. Gamma-ray irradiation to the MOSFETs was doned at the rate of 1MR/h at room temperature. As the result, the change of threshold voltage by irradiation is explained to be KD
, where K and n are constants.
Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro
Japanese Journal of Applied Physics, Part 2, 42(6B), p.L625 - L627, 2003/06
Times Cited Count：39 Percentile：77.43(Physics, Applied)The n-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100C. The 3C-SiC MOSFETs showed enhancement type behaviors after annealing at 200C for 30 min in argon atmosphere. The maximum value of the effective channel mobility of the 3C-SiC MOSFETs was 260 cm/Vs. The leakage current of gate oxide was of a few tens of nA/cm at an electric field range below 8.5 MV/cm, and breakdown began around 8.5 MV/cm.
lrradiated p-channel 6H-SiC MOSFETs; High total doseLee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
IEEE Transactions on Nuclear Science, 50(1), p.194 - 200, 2003/02
Times Cited Count：27 Percentile：84.38(Engineering, Electrical & Electronic)p-channel SiC MOSFETs were fabricated on n-type 6H-SiC epitaxial layer. The effects of -ray irradiation on the charecteristics of the MOSFETs were studied. Threshold voltage shifts to negative voltage side and the channel mobility reduces due to irradiation. Although the degradation of the channel mobility of the p-channel SiC MOSFETs is 10 times faster than n-channel SiC MOSFETs, p-channel SiC MOSFETs show 100 times stronger radiation resistance than Si MOSFETs. The values of interface traps and oxide-trapped-charge generated sue to irradiation were estimated from the subthreshold characteristics. As the result,it is concluded that the decrease in channel mobility can be explained by the generation of interface traps.
Lee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
Proceedings of 5th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications, p.73 - 76, 2002/10
no abstracts in English
Lee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
Materials Science Forum, 389-393, p.1097 - 1100, 2002/05
The effect of gamma-ray irradiation on electrical characteristics of n-channel and p-chanel enhancement type 6H-SiC MOSFET was studied. The gate oxide of the MOSFETs were formed using pyrogenic condition. Gamma-ray irradiation was carried out at room temperature at 8.8 kGy(SiO
)/hour. The channel mobility and thrshold voltage for the MOSFETs were estimated from I-V and I-V curves, respectively. The channel mobility for n-channel one does not change up to 1MGy. The channel mobility for p-channel one increases around 40 kGy and decreases above 40 kGy. This behavior is interpreted in terms of the compensation of intrinsic interface traps by the interface traps generated by irradiation. The fluctuation of thershold voltage for n-channel one by irradiation is less than 0.5V. For p-channel one, the threshold voltage decreases with increasing irradiation dose.
Oshima, Takeshi; Lee, K. K.; Oi, Akihiko; Yoshikawa, Masahito; Ito, Hisayoshi
Materials Science Forum, 389-393, p.1093 - 1096, 2002/05
Gamma-ray irradiation effects on the electrical characteristics such as threshold voltage (V) and channel mobility () for 6H-SiC MOSFETs were studied.The gate oxide of the MOSFETs were annealed in hydrogen at 700 or steam at 800 in fabrication process to improve the initial electrical characteristics of the MOSFETs.As for the hydrogen-annealed MOSFETs,V was changed from 0.9V to 3.1 V by irradiation at 530kGy. decreased after irradiation above 60 kGy. As for the steam-annealed MOSFETs,V was changed from 2.7 to 3.3 V by irradiation at 530kGy. decreased above 180 kGy. This indicates that radiation resistance for the steam-annealed MOSFETs is higher than that for the hydrogen-annealed MOSFETs.
