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Miyazaki, Tsukasa*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Takenaka, Mikihito*; Nakanishi, Yohei*; Shibata, Motoki*; Aoki, Hiroyuki; Yamada, Norifumi*; et al.
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 701, p.134928_1 - 134928_8, 2024/11
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)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.
Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Shibata, Motoki*; Nakanishi, Yohei*; Arakawa, Masato*; Takenaka, Mikihito*; Kida, Takumitsu*; Tokumitsu, Katsuhisa*; Tanaka, Ryo*; et al.
Langmuir, 40(30), p.15758 - 15766, 2024/07
Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)Nakanishi, Yohei*; Shibata, Motoki*; Sawada, Satoshi*; Kondo, Hiroaki*; Motokawa, Ryuhei; Kumada, Takayuki; Yamamoto, Katsuhiro*; Mita, Kazuki*; Miyazaki, Tsukasa*; Takenaka, Mikihito*
Polymer, 306, p.127209_1 - 127209_7, 2024/06
Times Cited Count：2 Percentile：56.40(Polymer Science) 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.
ion beam extracted from an RF wave excited ion source plasmaWada, Motoi*; Shibata, Takanori*; Shinto, Katsuhiro
Journal of Physics; Conference Series, 2743, p.012031_1 - 012031_5, 2024/05
Times Cited Count：0 Percentile：0.00(Physics, Particles & Fields)An internal antenna type RF driven negative hydrogen (H) ion source supplies beams to the J-PARC accelerator facility. The H ion beam current exhibits high stability, while it fluctuates with less than 5% amplitude of the DC current when a Faraday cup measures the current extracted from the source mounted on a test stand. Two frequencies are identified as the main oscillation components, 2 MHz and 4 MHz which are the driving RF frequency and the second harmonics, respectively. The amplitude levels of these components appear larger as parts of the beam directing specific angles passing through a slit are detected. A possible reason for observing a small amplitude oscillation in the total beam intensity is the averaged phase-shift of the local beam depending upon the position of the H ion production and the succeeding trajectory reaching the Faraday cup. To confirm if the phase-shift is the main reason for diminishing the oscillation amplitude for the total beam, the phase-shift between the 2 MHz and 4 MHz components were measured for beams passing through a 0.1 mm slit coupled to a Faraday cup having a 0.1 mm entrance slit. The result indicated the phase-shift changed substantially depending upon the position, but no simple model can explain the measured spatial distribution of the phase-shift. Further attempts will be made to clarify the beam dynamics relevant to the H ion beam transport including the measurements of the beam current phase-shift with respect to the RF antenna current, and the time evolution of Balmer-
light emission.
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.
Wada, Motoi*; Shibata, Takanori*; Shinto, Katsuhiro
Journal of Instrumentation (Internet), 19(2), p.C02019_1 - C02019_7, 2024/02
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)A negative hydrogen (H) ion source with the plasma excited by 2 MHz radio frequency (RF) power serves as the beam source for the Japan Proton Accelerator Research Complex (J-PARC). We have been studying the H ion beam intensity modulation at the frequency of plasma excitation RF power since we have found the beam carried the fluctuation at 2 MHz after the RFQ linac. Higher frequency components were found present in the peripheral region of the plasma, and the highspeed emittance measurement system developed to clarify the change of the beam in phase space revealed the existence of diverging halo component oscillating at 2 MHz. The fluctuation amplitude at the beam center was less than about 20%, while there was observed the component oscillating at 4 MHz. The 4 MHz component seems related to the production of high energy electrons by the RF antenna as the intensity of the RF induction electric field takes the maximum twice in each cycle. On the other hand, the direction of RF magnetic field and the direction of electron flow change at 2 MHz frequency. Thus, H ion formation mechanisms in the ion source can be estimated through precisely characterizing the extracted H ion beam. The H ion beam fluctuation can be observed in the H ion current measured with a Faraday cup. Before introducing Cs, the measured beam current showed the fluctuation at 4 MHz frequency when the axial magnetic field correction (AMFC) coil was turned off. The main fluctuation frequency changed to 2 MHz as the voltage to excite the coil to induce AMFC was increased. Injection of Cs into the ion source increased the H ion current, while the 4 MHz component nearly disappeared for both cases of AMFC on and AMFC off. Possible mechanisms responsible for diminishing 4 MHz fluctuation component by Cs injections are discussed.
Shibata, Takanori*; Shinto, Katsuhiro; Nammo, Kesao*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo; Ishida, Masaki*; Wada, Motoi*
Journal of Instrumentation (Internet), 19(1), p.C01009_1 - C01009_8, 2024/01
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)From Nov. 2020 to Apr. 2021, the continuous ion source operation for 3,651 hours (5 months) was achieved. As the lifetime of the RF ion source is mainly limited by failure on the enamel coating of the RF antenna, detailed evaluation of the antenna surface is required to ensure feasibility of the further extension of the operation time. In the present study, surface discoloration on the RF antenna coil observed after the 5 months operation is investigated by application of digital microscope and SEM/EDS analyses. The material mapping and the line spectrum obtained by the EDS analysis show that depositions of the sputtered source chamber wall materials and the injected cesium on to the enamel coating are the most possible candidate for the discoloration. The dimension measurements of the RF antenna thickness before and after the long-term operation support the idea that the discoloration is due to the deposited materials and hence insulation of the RF antenna coil by enamel coating is maintained. The emittance measurement after the operation also shows that the RF plasma and the beam formations are not affected by the deposition on the antenna.
Shibata, Motoki*; Nakanishi, Yohei*; Abe, Jun*; Arima, Hiroshi*; Iwase, Hiroki*; Shibayama, Mitsuhiro*; Motokawa, Ryuhei; Kumada, Takayuki; Takata, Shinichi; Yamamoto, Katsuhiro*; et al.
Polymer Journal, 55(11), p.1165 - 1170, 2023/11
Times Cited Count：2 Percentile：19.24(Polymer Science)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.
Shinto, Katsuhiro; Shibata, Takanori*; Wada, Motoi*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.392 - 395, 2023/11
Negative hydrogen (H) ion sources which are used at high-intensity proton accelerator facilities such as J-PARC or neutral beam injection system for plasma heating in the fusion devices such as ITER produce plasmas by using RF sources driving with the frequency of 1-2 MHz. We have shown that the H beams extracted from the RF-driven H ion source with the frequency of several MHz have some fluctuations with the frequency of the fundamental and second harmonics. The reason is that the high plasma density is produced in the ion source with the low driving frequency. Therefore, we propose the driving RF frequency same as the RF sources with that of 324 MHz in the J-PARC linac, which is much higher than the ion plasma frequency, is used for producing the plasma to suppress the H beam fluctuations. As a first step, we performed a design of a matching circuit for the higher frequency driven H ion source. We present the background for decision of a new RF amplifier with much higher frequency and the design results.
Nakahara, Masaumi; Shibata, Atsuhiro
Journal of Nuclear Science and Technology, 60(7), p.849 - 858, 2023/07
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)To develop the acid split method which has highly nuclear proliferation resistance, influence of Pu content in dissolver solutions derived from irradiated fast reactor fuel on the Pu stripping was investigated in experiments and a calculation. The Pu content in the U/Pu and U products increased with increasing the Pu content in the dissolver solution. Moreover, the calculated results indicate that the Pu leakage into the U product is suppressed with the Pu stripping solution only at low temperature.
Takahatake, Yoko; Watanabe, So; Arai, Tsuyoshi*; Sato, Takahiro*; Shibata, Atsuhiro
Applied Radiation and Isotopes, 196, p.110783_1 - 110783_5, 2023/06
Times Cited Count：2 Percentile：46.61(Chemistry, Inorganic & Nuclear)Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Nakanishi, Yohei*; Shibata, Motoki*; Takenaka, Mikihito*; Yamada, Norifumi*; Seto, Hideki*; Aoki, Hiroyuki; Miyazaki, Tsukasa*
Soft Matter, 19(11), p.2082 - 2089, 2023/03
Times Cited Count：3 Percentile：52.54(Chemistry, Physical) ion sourceShinto, Katsuhiro; Shibata, Takanori*; Okoshi, Kiyonori; Nammo, Kesao*; Ikegami, Kiyoshi*; Oguri, Hidetomo
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.675 - 679, 2023/01
In J-PARC, we have been conducting the test of a J-PARC-made internal antenna in order to establish the production method and understand the beam characteristics of the antenna. At this time, we investigated the outgas characteristics during the production of a high-density plasma by using the J-PARC-made antenna. It is confirmed that no remarkable impurities are emitted from the antenna by a residual gas analysis using a quadrupole mass analyzer installed downstream the ion source and a spectroscopic analysis of the plasma in the ion source. It is found that the emittances of the H beam extracted from the J-PARC radio-frequency H ion source by using the antenna was similar as those in case by using SNS antenna.
Shibata, Takanori*; Ishida, Masaki*; Nammo, Kesao*; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Shinto, Katsuhiro; Oguri, Hidetomo
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.863 - 867, 2023/01
Continuous operation duration of the J-PARC Radio Frequency (RF) ion source has been extended step by step these years for the goal to supply stable beam during the entire period of J-PARC user operation (around 7 months) each year. A 3651 hours (5 months) continuous ion source operation has been achieved from Nov. 2020 to Apr. 2021. As the lifetime of the ion source is mainly limited by failure on the RF antenna coil, detailed evaluation of the antenna surface condition is required to ensure the feasibility of the further extension of the operation time. In the present study, dimension measurements and SEM/EDS analyses were applied to understand the surface discoloration of the RF antenna. The discoloration after the long-term continuous operation is due to deposition of injected cesium (for H surface production process) and of stainless used steel (Fe, Cr, Ni) from the ion source components sputtered by plasma. The results show that the enamel coating of the RF antenna has not worn out in the long-term continuous operation for several months and, hence, extension of the ion source continuous operation duration can be extended.
Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Nakanishi, Yohei*; Takenaka, Mikihito*; Shibata, Motoki*; Yamada, Norifumi*; Seto, Hideki*; Aoki, Hiroyuki; et al.
Langmuir, 38(41), p.12457 - 12465, 2022/10
Times Cited Count：2 Percentile：13.50(Chemistry, Multidisciplinary)Nakahara, Masaumi; Watanabe, So; Aihara, Haruka; Takahatake, Yoko; Arai, Yoichi; Ogi, Hiromichi*; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori
Proceedings of International Conference on Nuclear Fuel Cycle; Sustainable Energy Beyond the Pandemic (GLOBAL 2022) (Internet), 4 Pages, 2022/07
Various radioactive wastes have been generated from Chemical Processing Facility for basic research on advanced reactor fuel reprocessing, radioactive waste disposal, and nuclear fuel cycle technology. Many types of reagents have been used for the experiments, and some troublesome materials were produced in the course of experiments. The radioactive liquid wastes were treated for stable and safe storage using decomposition, solvent extraction, precipitation, and solidification methods. In this study, current status of harmless treatment for the radioactive liquid wastes would be reported.
