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Journal Articles

Development of semiconductor switches for high-power crowbar circuits for J-PARC accelerator

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.

Journal Articles

Operation status of the J-PARC high-intensity RF-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.928 - 931, 2023/11

J-PARC initiated the operation of the high-intensity rf-driven negative hydrogen (H$$^-$$) ion source in 2014 autumn. The ion source produces the H$$^-$$ beam with the beam current of 60 mA and the beam energy of 50 keV in order to inject the H$$^-$$ beam into the 3 GeV RCS with the beam current of 50 mA and the beam energy of 400 MeV from the J-PARC linac. We have achieved the longest continuous operation time of 4001 hours in the previous (2021/2022) campaign. The 2022/2023 campaign was the first time that the continuous operation of the H$$^-$$ ion source without any exchanges of the ion source until the end of the campaign was examined. We present the operation status of the J-PARC H$$^-$$ ion source in this campaign as well as the status of the J-PARC-made internal antenna test.

Journal Articles

Development of semiconductor switches for high-power crowbar circuits

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 $$mu$$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.

Journal Articles

Semiconductor pulse power supplies for accelerators at J-PARC

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$$mu$$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/830$$mu$$s 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.

Journal Articles

Construction of low-jitter circuit for new kicker power supply using next-generation power semiconductor

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.

Journal Articles

Impurities reduction conditionings to recover best beam quality of J-PARC cesiated RF-driven H$$^{-}$$ ion source with new parts exposed to plasma

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo

Journal of Physics; Conference Series, 2244, p.012029_1 - 012029_5, 2022/04

 Times Cited Count:0 Percentile:0.32

The J-PARC cesiated RF-driven H$$^{-}$$ ion source is stably suppling about 58 mA beam with a duty factor of 1.25 % (0.5 ms$$times$$25 Hz) for the J-PARC LINAC 50 mA operations. For them, only three plasma chambers (PCHs) of #7, #8 and #9PCHs among ten PCHs have been used since the transverse emittances are more superior than others for unknown reasons. However, the emittances were enlarged by 16 % with the #7PCH, in which the plasma electrode (PE) temperature control plate (PETCP) was replaced to brand-new one to solve the air leak at the VCR vacuum fitting. The impurities from the new parts exposed to the plasma seemed to cause the degradation. The beam with almost the best emittances was reproduced by #4PCH with a new PETCP, in which sapphire tubes were used instead of the 99.7 % alumina ceramics tubes, after a new 2-MHz RF power scanning impurities reduction conditioning for 48 hours.

Journal Articles

Negative hydrogen ion sources for particle accelerators; Sustainability issues and recent improvements in long-term operations

Welton, R.*; Bollinger, D.*; Dehnel, M.*; Draganic, I.*; Faircloth, D.*; Han, B.*; Lettry, J.*; Stockli, M.*; Tarvainen, O.*; Ueno, Akira

Journal of Physics; Conference Series, 2244, p.012045_1 - 012045_13, 2022/04

 Times Cited Count:0 Percentile:90.35

High brightness, negative hydrogen ion sources are used extensively in many scientific facilities operating worldwide. Negative hydrogen beams have become the preferred means of filling circular accelerators and storage rings. Several facilities now have long-term ($$>$$ several years) experience with operating a variety of these sources (RF, filament, magnetron and penning) and have encountered, and in some cases solved, performance limiting issues. A representative list of such facilities includes, the US Spallation Neutron Source (SNS), Japan Proton Accelerator Complex (J-PARC), Rutherford Appleton Laboratory (RAL-ISIS), Los Alamos Neutron Science Center (LANSCE), Fermi National Accelerator Laboratory (FNAL), CERN LINAC-4 and numerous installations of D-Pace ion sources. This report summarizes key ion source sustainability issues encountered at these facilities and discusses how some of them are being addressed through recent source improvements.

Journal Articles

110 mA operation of J-PARC cesiated RF-driven H$$^{-}$$ ion source

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shinto, Katsuhiro; Oguri, Hidetomo

AIP Conference Proceedings 2373, p.040002_1 - 040002_8, 2021/07

On 2018, the stable operation of the J-PARC cesiated RF-driven H$$^{-}$$ ion source (IS) with a 62 keV 100 mA beam, whose emittances were suitable for the radio-frequency quadrupole LINAC (RFQ), was reported. In the J-PARC IS operation, the stable plasma production with a 50 kW 2 MHz RF power for more than 3 months, an RF power efficiency higher than 2.4 mA/kW and the possibility of the space charge limited beam intensity pulling up by increasing the extraction and acceleration voltages were proven. On the other hand, the withstand voltage for the stable operation with an RF plasma production of the present 2 MHz matching circuit and the high voltage power supply was measured as about 66 kV. In the operation with the presently highest beam energy of 65 keV, a 110 mA beam with emittances suitable for the RFQ was stably produced. Since 102.5 mA of the beam was measured inside the emittances used for the RFQ design, the next generation 100 mA LINAC will be possible with the IS.

Journal Articles

Status of the J-PARC RF-driven H$$^{-}$$ ion source

Oguri, Hidetomo; Okoshi, Kiyonori; Shinto, Katsuhiro; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira

JPS Conference Proceedings (Internet), 33, p.011008_1 - 011008_7, 2021/03

A cesiated RF-driven negative hydrogen ion source was initiated to operate in September, 2014 in response to the need for upgrading J-PARC's linac beam current. The ion source mainly comprises a stainless-steel plasma chamber, a beam extractor and a large vacuum chamber equipped with two turbo molecular pumps, each having the pumping speed of 1500 L/s, for differential pumping. The user operation was started with the beam current of 33 mA from the ion source. We gradually increased both beam current and continuous operation time of the ion source. In July, 2018 (Run#79), approximately 2,200 hours operation was achieved with the typical beam current, pulse length and repetition rate of 47 mA, 300 $$mu$$s and 25 Hz, respectively. Since October, 2018 (Run#80), the ion source has been delivering a nominal beam current of approximately 60 mA.

Journal Articles

J-PARC H$$^{-}$$ ion source and space-charge neutralized LEBT for 100-mA high energy and high duty factor LINACs

Ueno, Akira

Review of Scientific Instruments, 91(3), p.033312_1 - 033312_9, 2020/03

 Times Cited Count:4 Percentile:29.37(Instruments & Instrumentation)

In July 2019, a 3 GeV 920 kW beam was accelerated for 10.5 hours in the J-PARC. During the operation, the H$$^{-}$$ ion source and LINAC was operated with the beam duty factor (BDF) of 1.25% (0.5 ms$$times$$25 Hz) and the ejected beam intensities of 58 and 50 mA, respectively. Separately, they were stably operated with the BDF of 1.5% (0.6 ms$$times$$25 Hz) and the ejected beam intensities of 72 and 60 mA, respectively. Based upon the 100-mA and BDF 5% (1 ms$$times$$50 Hz) H$$^{-}$$ ion source operation on a test-stand, the possibility of the 100-mA high energy and high duty factor LINACs with a radio frequency quadrupole LINAC with an injection energy higher than 64 keV is presented. The unexpectedly effective space-charge neutralization effects in the low energy beam transport are also presented. Furthermore, the transverse emittance improvements by about 8% with the shortest beam extractor are presented.

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Shibata, Takanori*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira; Oguri, Hidetomo

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.554 - 557, 2019/07

In September 2014, a cesiated RF-driven negative hydrogen ion (H$$^{-}$$) source was initiated to operate at the Japan Proton Accelerator Research Complex (J-PARC). The extracted H$$^{-}$$ beam current and the continuous operation time of the ion source have been improved upon their own records. In the RUN#79 (from April to July 2018), the ion source delivered the H$$^{-}$$ beam current of 47 mA to the post-accelerators for 2,201 hours continuously. In October 2018, the beam current from the ion source was increased to 60 mA in order to inject the beam current of 50 mA into the 3 GeV synchrotron. In the RUN#80 (from October to December 2018), the continuous operation time of 1,791 hours was achieved. For the past year, we had the antenna failures twice during the operation, and needed to replace to a spare ion source. We have been developed the J-PARC-made antenna by using a test-stand. Recent experiment result showed the continuous operation time of 2,083 hours was achieved with the J-PARC-made antenna.

Journal Articles

New precise measurements of muonium hyperfine structure at J-PARC MUSE

Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.

EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01

 Times Cited Count:13 Percentile:99.28

Journal Articles

Solving beam intensity bottlenecks and 100 mA operation of J-PARC cesiated RF-driven H$$^{-}$$ ion source

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shinto, Katsuhiro; Oguri, Hidetomo

AIP Conference Proceedings 2052, p.050003_1 - 050003_7, 2018/12

 Times Cited Count:2 Percentile:72.2

In order to specify the beam intensity bottlenecks of the J-PARC cesiated RF-driven H$$^{-}$$ ion source, the extraction and acceleration voltages (V$$_{rm E}$$ and V$$_{rm A}$$) higher than the design values of 10 kV and 40 kV were examined. A 100 mA beam, whose about 93 mA has transverse emittances used for a common RFQ design, was stably operated with a duty factor of 5% (1 ms $$times$$ 50 Hz) by using the V$$_{rm E}$$ and V$$_{rm A}$$ of 12.4 kV and 49.6 kV, respectively. This breakthrough with important information on the space-charge limited bottlenecks in the extraction and acceleration gaps will derive the optimal electrode shapes for the source operated with a beam intensity higher than 100 mA and realize the next generation benchmark H$$^{-}$$ ion source for high intensity and high energy H$$^{-}$$ LINACs.

Journal Articles

Progress of the J-PARC cesiated rf-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2052, p.050002_1 - 050002_7, 2018/12

 Times Cited Count:6 Percentile:93.99

In the 2017/2018 campaign, the J-PARC cesiated rf-driven negative hydrogen (H$$^-$$) ion source producing H$$^-$$ beam with the beam current of 47 mA accomplished three long-term operations more than 2,000 hours without any serious issues. On the final day of this campaign, the ion source produced an H$$^-$$ beam current of 72 mA so that the linac commissioning group could demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. The antenna achieved the operation time approximately 1,400 hours.

Journal Articles

Present status of the J-PARC cesiated rf-driven H$$^-$$ ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shibata, Takanori*; Nammo, Kesao*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2011, p.050018_1 - 050018_3, 2018/09

 Times Cited Count:3 Percentile:82.43

Journal Articles

How to make extraction electrode current lower than beam and corresponding beam qualities in J-PARC cesiated RF-Driven H$$^{-}$$ ion source 66 mA operation

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shinto, Katsuhiro; Oguri, Hidetomo

AIP Conference Proceedings 2011, p.050002_1 - 050002_5, 2018/09

In order to operate the J-PARC cesiated rf-driven H$$^{-}$$ ion source with a beam intensity of 66 mA stably, the conditions to minimize the extraction electrode current (I$$_{EE}$$), whose main component is the electron current co-extracted with the beam, were investigated. The 66 mA H$$^{-}$$ ion beam with a low I$$_{EE}$$ of about 40 mA, which was one-fourth of that in the ordinal operation, were stably extracted by optimizing a rod-filter-field (RFF), a cesium (Cs) density and an axial magnetic field correction (AMFC). Especially, the AMFC of only 40 Gauss had the largest I$$_{EE}$$ reduction of about one-third. The corresponding 95 % beam transverse normalized rms emittances were degraded about 24 % due to the higher RFF and Cs density. The source will be operated in the conditions to compromise the stability and the beam quality by the investigated results.

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Shibata, Takanori*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira; Namekawa, Yuya*; Oguri, Hidetomo

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.889 - 892, 2018/08

In 2017-2018 campaign, three times of long-time operation more than 2,000 hours of the J-PARC rf-driven negative hydrogen (H$$^{-}$$) ion source producing H$$^{-}$$ beam with the beam current of 47 mA were successfully achieved without any serious problems. At the final day of this campaign, the ion source produced an H$$^{-}$$ beam with the current of 72 mA in order to demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. Approximately 1,400-hour operation with the antenna was successfully performed.

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Ikegami, Kiyoshi*; Shibata, Takanori*; Takagi, Akira*; Nammo, Kesao*; Ueno, Akira; Oguri, Hidetomo

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.651 - 654, 2017/12

Operation of a cesiated rf-driven negative hydrogen ion source was initiated in September 2014 in response to the requirements of beam current upgrade in J-PARC linac. Delivery of the required beam current from the ion source to the J-PARC accelerators has been successfully performed. In 2016-2017 campaign, continuous operation of the ion source for approximately 1,845 hours (from April to July 2017) was achieved with beam current of 47 mA.

Journal Articles

Development of a new power supply for the RCS kicker magnet with the LTD circuit of SiC-MOSFETs

Takayanagi, Tomohiro; Kinsho, Michikazu; Yamamoto, Kazami; Ueno, Tomoaki*; Horino, Koki*; Tokuchi, Akira*; Mushibe, Yoichi*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.45 - 49, 2017/12

J-PARC RCS needs updating of equipment after 10 years since the start of operation. Therefore, a pulse power supply applying a next generation semiconductor (SiC-MOSFET) with low switching loss and high breakdown voltage are investigated This supply constructs a serial / parallel multiplexing circuit using a SiC-MOSFET and a plurality of large capacity capacitors with one circuit board (LTD). By using this board as a main board and adopting a multistage hierarchical structure, it is possible to satisfy the specifications of the RCS kicker power supply with a voltage of 40 kV, a current of 4 kA and a rectangular wave pulse width of 1500 ns. Moreover, by adding a plurality of correction boards of 40 V and arbitrarily setting the operation trigger of the board, flatness correction is also possible. It was confirmed that the results of the preliminary test with the maximum output of 4 kV / 2 kA by are effective for maintaining stable operation at the RCS high intensity beam output.

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:3 Percentile:86.59

114 (Records 1-20 displayed on this page)