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ion sourceShibata, Takanori*; Shinto, Katsuhiro; Nammo, Kesao*; Okoshi, Kiyonori; Kawai, Isao*; Ikegami, Kiyoshi*; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011155_1 - 011155_10, 2026/06
Shibata, Takanori*; Nakano, Haruhisa*; Wada, Motoi*; Shinto, Katsuhiro; Okoshi, Kiyonori; Nammo, Kesao*; Kawai, Isao*; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011154_1 - 011154_8, 2026/06
In the high-power proton accelerator facilities, Radio Frequency (RF) driven negative hydrogen ion (H) sources are adopted as particle sources for the maintenance-free duration over several months and for the stability of the H beam characteristics in the long-term operation. Techniques of RF plasma excitation are also introduced in the fusion field as ion sources of the neutral beam injection (NBI). On the other hand, the RF ion sources have a feature that the extracted beam current and phase space show slight oscillation with input RF frequency. The oscillation of the phase space may lead to mismatches of Twiss parameters or beam loss at the accelerator cavities in the higher-power beam operation. A 3D Particle-In-Cell (PIC) modeling based on Monte-Carlo collision was developed to elucidate the beam oscillation mechanisms. The presentation reports the effects upon the beam formation due to the electric potential fluctuation caused by a capacitive coupling to the internal antenna coil.
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki*; Ueno, Akira; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011137_1 - 011137_10, 2026/06
In the autumn of 2014, we initiated the operation of a cesiated radio frequency (RF)-driven negative hydrogen (H) ion source at J-PARC in response to the necessity for increased beam intensities in the experimental facilities. The RF-driven ion source has extracted H beams with a beam energy of 50 keV and a beam current of 33 mA at the outset, 47 mA since January 2016, and 60 mA since October 2018. The last value fulfills the requirement that the linac injects the H beams with a beam current of 50 mA as specified in the initial design value into the 3-GeV rapid-cycling synchrotron (RCS). Prior to the 2021/2022 campaign, the ion source had been exchanged on one to three occasions during a campaign. Because it was challenging to ascertain the operational longevity that the RF-driven ion source could deliver beams without any significant issues necessitating the suspension of operations. However, from the 2022/2023 campaign onwards, a single RF-driven H ion source has functioned to deliver the H beams, with the continuous operation time exceeding 4,400 hours. Over the course of this decade, three instances of antenna failure and several other issues have been encountered. This presentation provides the statistical data pertaining to the RF-driven H ion source in terms of user operations, along with an overview of the R&D status in relation to the future J-PARC upgrades.
ion beam at J-PARC frontendShibata, Takanori*; Nammo, Kesao*; Shinto, Katsuhiro; Okoshi, Kiyonori; Kawai, Isao*; Kitamura, Ryo; Morishita, Takatoshi; Kondo, Yasuhiro; Sato, Yoichi*
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.514 - 516, 2025/11
no abstracts in English
Kawai, Keito*; Nemoto, Yoshiyuki; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Mohamad, A. B.; Pham, V. H.; Ishikawa, Norito; Ishijima, Yasuhiro; Ioka, Ikuo; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 24(3), p.82 - 98, 2025/08
An accident tolerant fuel (ATF) cladding, which is more resistant to accidents than the conventional Zircaloy cladding, is under development. One of these claddings is a chromium (Cr)-coated cladding with an outer surface coated with Cr, which is expected to improve the resistance to high-temperature steam oxidation. In this study, electrochemical plating was applied to coat a Cr layer on the cladding outer surface, and its properties under accidental conditions were evaluated. In a loss-of-coolant accident (LOCA), the cladding will burst and both the outer and inner surfaces of the cladding will be oxidized. Thus, as-received Zircaloy-4 and Cr-coated claddings were tested for oxidation in high-temperature steam to investigate differences in oxidation behavior, hydrogen absorption behavior, and mechanical properties after oxidation. Oxidation tests were conducted using a thermobalance. The amount of oxidation of coated samples decreased by half compared with that of uncoated samples, indicating that the coating was effective in inhibiting oxidation. However, the hydrogen absorption of coated samples was found to be higher than that of uncoated samples. In this paper, we discuss the mechanism behind this difference in hydrogen absorption and its effect on mechanical properties.
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.525 - 528, 2024/10
A decade has elapsed since the radio frequency (RF)-driven negative hydrogen (H) ion source initiated operation at J-PARC. In the 2023/2024 campaign, a single RF-driven H ion source has generated H beams with a beam current of 60 mA, which enabled the J-PARC linac to inject them into the 3 GeV rapid cycling synchrotron (RCS) with a beam current of 50 mA. The continuous operation time of the ion source reached exceeding 4,900 hours in this campaign, which signifies a notable enhancement in operational longevity in comparison to the preceding longest campaign in 2022/2023, which spanned 4,412 hours. This paper provides the operational status of the RF-driven H ion source during this campaign and the current status of the J-PARC-made antenna, which is currently under development.
ion sourceShibata, Takanori*; Okoshi, Kiyonori; Ueno, Akira; Ikegami, Kiyoshi*; Shinto, Katsuhiro; Nammo, Kesao*; Kawai, Isao*; Oguri, Hidetomo
Kasokuki, 21(2), p.94 - 100, 2024/07
In the recent J-PARC user operation from Nov. 10th, 2022 to Jun. 22nd, 2023, continuous operation of 4,412 hours with hydrogen negative ion (H ion) beam current up to 60 mA was achieved by J-PARC radio frequency (RF) H ion source. This was also the first time to supply H ion beam to the linac in the yearly J-PARC user operation term by a single ion source (w/o ion source exchange). To satisfy the requirements of the further upgrade in J-PARC, a soundness evaluation of the present ion source components has been performed. Furthermore, the RF ion source with a newly manufactured RF antenna coil has been under development.
Shibata, Takanori*; Shinto, Katsuhiro; Nakano, Haruhisa*; Hoshino, Kazuo*; Miyamoto, Kenji*; Okoshi, Kiyonori; Nammo, Kesao*; Ikegami, Kiyoshi*; Kawai, Isao*; Oguri, Hidetomo; et al.
Journal of Physics; Conference Series, 2743, p.012007_1 - 012007_5, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Particles & Fields)Oscillation of the negative hydrogen ion (H) beam phase space in Radio Frequency (RF) ion source is investigated by a simple 3D Particle-In-Cell (PIC) model which takes into account the transport processes of electron, proton and H in the extraction region. The calculation domain is in vicinity of the single beam aperture in J-PARC ion source configuration. In order to understand relation between the plasma density oscillation and the extracted H beam characteristics, the input electron and proton fluxes from the driver region are varied parametrically with the 1st and the 2nd harmonics of the J-PARC RF frequency (2 or 4 MHz). The numerical results give an idea to the main physical processes between the oscillations of the plasma parameters and the extracted H ion trajectories in the different RF phases. Countermeasures to reduce the oscillation mechanisms are also discussed in the presentation.
ion sourceShinto, Katsuhiro; Shibata, Takanori*; Okoshi, Kiyonori; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*
Journal of Physics; Conference Series, 2743, p.012023_1 - 012023_5, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Particles & Fields)We have been conducting the test of a new J-PARC-made internal antenna for the J-PARC RF-driven cesiated H ion source. After the development of the first J-PARC-made antenna, the composition of the porcelain enamel coating of the antenna was changed because we were afraid of the outgassing of the impurities from the previous antenna coating. During the test of high-density plasma production by the new antenna, we monitored the outgassing characteristics of the new antenna by measuring mass spectrometry and optical spectrum analysis. It is confirmed that no remarkable impurities were emitted from the new antenna. We also carried out the H beam extraction and measured the H beam characteristics by using the new antenna. It is found that the emittances of the H beam extracted from the J-PARC RF-driven cesiated H ion source by using the new antenna were similar to those in the case by using the SNS-made antenna. To accelerate the endurance test of the new antenna, we applied the antenna for the high-density plasma production to the 5% duty factor (1 ms pulse width with 50 Hz repetition rate) with the 2 MHz RF input power of approximately 60 kW, whose values were much higher than those in the J-PARC nominal operation; 0.8 ms pulse width with 25 Hz repetition rate (the duty factor of 2%) with the RF input power of approximately 30 kW. This presentation shows the results of the characteristics of the new J-PARC-made antenna and discusses the feasibility of the new antenna for use in the J-PARC accelerator operation.
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.
Komata, Masao; Kazawa, Minoru; Mogaki, Kazuhiko; Kawai, Mikito; Seki, Norikatsu; Nemoto, Shuji; Hanada, Masaya; Nishizawa, Isao*; Otsuki, Shinichi*
no journal, ,
no abstracts in English
Kawai, Keito*; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Ishikawa, Norito; Nemoto, Yoshiyuki; Yamashita, Shinichiro; Ishijima, Yasuhiro; Ioka, Ikuo; Funamoto, Kodai*; et al.
no journal, ,
In the previous report, we reported on the differences in oxidation and hydrogen absorption behavior of Zircaloy-4 cladding specimen and specimen with chromium (Cr) coating on its outer surfaces when they were subjected to oxidation tests in high temperature steam at 1100
C for 20 minutes. In this report, we describe the details of the cross-sectional observation of these specimens and the results of the evaluation of the differences in the shape and distribution of hydrides and other substances depending on the presence or absence of Cr coating.
Kawai, Keito*; Nemoto, Yoshiyuki; Yamashita, Shinichiro; Ishijima, Yasuhiro; Ioka, Ikuo; Funamoto, Kodai*; Atsumi, Hisao*
no journal, ,
no abstracts in English
Mogaki, Kazuhiko; Hanada, Masaya; Kawai, Mikito; Kazawa, Minoru; Akino, Noboru; Komata, Masao; Usui, Katsutomi; Oasa, Kazumi; Kikuchi, Katsumi; Shimizu, Tatsuo; et al.
no journal, ,
no abstracts in English
Kawai, Keito*; Nemoto, Yoshiyuki; Fujimura, Yuki; Kondo, Keietsu; Abe, Yosuke; Mohamad, A. B.; Pham, V. H.; Ishikawa, Norito; Ishijima, Yasuhiro; Ioka, Ikuo; et al.
no journal, ,
no abstracts in English
