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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.
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.
ion source with new parts exposed to plasmaUeno, 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(Engineering, Electrical & Electronic)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
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.
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：2 Percentile：89.37(Engineering, Electrical & Electronic)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.
Shibata, Takanori*; Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Ikegami, Kiyoshi*; Oguri, Hidetomo
Journal of Physics; Conference Series, 2244, p.012041_1 - 012041_5, 2022/04
Times Cited Count：1 Percentile：0.32(Engineering, Electrical & Electronic)In the J-PARC user operation from Nov. 2020 - Apr. 2021, continuous operation of J-PARC Radio Frequency (RF) negative hydrogen ion (H) source up to 3,651 hours (5 months) has been achieved. The ion source was operated with the output H current of 60 mA, the duty factor (for plasma generation) 2% and the input RF power up to 30 kW. After the operation, phase space diagrams at the Radio Frequency Quadrupole (RFQ) entrance were measured by the emittance monitor at the ion source test stand (IS-TS) under the same operation condition as in the J-PARC Linac. Comparison of the phase spaces and the beam emittances between the ion sources in the present and the previous operations shows slight difference. From the direct observation of the antenna coil, no exhaustion or the decrease in the thickness of the enamel coating of the coil have been confirmed. The results indicate the possibility of the next goal of the long-run up to 7 months, which is the same as the full duration of the J-PARC user operation in 1 year.
beam extracted from an RF-driven high-intensity H ion sourceShinto, Katsuhiro; Shibata, Takanori*; Wada, Motoi*
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.230 - 233, 2021/10
In most proton accelerator facilities such as J-PARC, SNS, CERN, a H ion source equipped with a 2-MHz rf driver for plasma generation produces H beams. We have reported H beam characteristics extracted from the J-PARC rf-driven high-intensity H ion source. We have been developing an emittance measurement apparatus equipped with a highly time-resolved data acquisition system in order to observe fluctuation of the beam emittance in association with the frequency of the rf driver. By using this apparatus, we found that the beam emittance is fluctuated with the frequency with the rf driver and higher harmonics. We will show some obtained results of the emittance fluctuation.
Shibata, Takanori*; Hirano, Koichiro; Hirane, Tatsuya*; Shinto, Katsuhiro; Hayashi, Naoki; Oguri, Hidetomo
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.417 - 421, 2021/10
In J-PARC linac, the operation of an rf-driven high-intensity H ion source was initiated in 2014. For plasma ignition, the 2-MHz rf amplifier outputs the power of several tens kW. However the rf amplifier for the ion source and those for the accelerating cavities have not been synchronized. As a result, the wave hights in the beam waveforms were different in shot by shot. Therefore, we have developed an synchronization system between the rf system for the ion source and those for the cavity systems and succeeded the same wave hights in the waveforms.
Shibata, Takanori*; Shinto, Katsuhiro; Wada, Motoi*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*
AIP Conference Proceedings 2373, p.050002_1 - 050002_9, 2021/08
Oscillation of emittance and Twiss parameters in the negative ion beam from the J-PARC 2-MHz RF ion source is measured by applications of a double-slit emittance monitor located at the RFQ (Radio Frequency Quadrupole) entrance. The emittance monitor is equipped with a newly-developed 60 MS/s data acquisition system, so that beam current oscillation in a few MHz can be observed with enough time resolution. From the measurement, it is shown that the beam phase space consists of (1) a DC component in the beam core, (2) a 2-MHz oscillating component which takes place both in the beam core and the halo and (3) a doubled RF frequency (4 MHz) oscillation which slightly exists in the beam halo. The major component is the 2-MHz component, which resultantly decides the beam emittance oscillation frequency. A typical value of the beam emittance in the present experiment is 0.34 
mm-mrad, while the amplitude of the 2 MHz oscillation is around 0.04 mm-mrad. The results indicate that the high-frequency oscillation component occupying about ten-percent of the beam from the RF source travels a few meters passing through a magnetic lens focusing system.
Sarmento, T.*; W
nderlich, D.*; Fantz, U.*; Friedl, R.*; Rauner, D.*; Tsumori, Katsuyoshi*; Shenjin, L.*; Chen, W.*; Bollinger, D.*; Oguri, Hidetomo; et al.
AIP Conference Proceedings 2373, p.110001_1 - 110001_18, 2021/08
In preparation for NIBS 2020 various labs prepared reference sheets containing key information about their ion sources and the machines that they serve. The contents of the reference sheets have been formatted and edited into this paper for posterity and ease of access.
ion source and space-charge neutralized LEBT for 100-mA high energy and high duty factor LINACsUeno, Akira
Review of Scientific Instruments, 91(3), p.033312_1 - 033312_9, 2020/03
Times Cited Count：4 Percentile：28.61(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 ms25 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 ms25 Hz) and the ejected beam intensities of 72 and 60 mA, respectively. Based upon the 100-mA and BDF 5% (1 ms50 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.
Oguri, Hidetomo
Purazuma, Kaku Yugo Gakkai-Shi, 95(7), p.340 - 344, 2019/07
no abstracts in English
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：93.93(Physics, Applied)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.
ion sourceShinto, 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：82.15(Physics, Applied) ion sourceShinto, Katsuhiro; Shibata, Takanori*; Miura, Akihiko; Miyao, Tomoaki*; Wada, Motoi*
AIP Conference Proceedings 2011, p.080016_1 - 080016_3, 2018/09
Times Cited Count：5 Percentile：91.75(Physics, Applied)Shibata, Takanori*; Shinto, Katsuhiro; Takagi, Akira*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*; Naito, Fujio*
AIP Conference Proceedings 2011, p.020008_1 - 020008_3, 2018/09
Times Cited Count：5 Percentile：91.75(Physics, Applied) ion source upon the extracted beamShinto, Katsuhiro; Shibata, Takanori*; Wada, Motoi*
Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.648 - 650, 2017/12
In J-PARC, peak H current of several tens mA is extracted from an ion source driven by a solid-state rf amplifier with the frequency of 2 MHz for production of a cesiated hydrogen plasma. In case of the rf-driven ion source for producing the high-intensity H current, the plasma density in the source chamber is so high that the ion sheath around the beam extraction area can follow the rf oscillation. The H beam current fluctuation as large as approximately 1 mA was observed at the average beam current of 44 mA measured by a Faraday cup installed downstream of the ion source. The beam exhibited some fluctuation to the transverse motion as well. To further clarify this high frequency oscillation of the beam extraction sheath, we propose a measurement system using a time-resolved and highly sensitive emittance monitor in order to observe the real-time beam fluctuation in the phase space.
ion sourceOguri, Hidetomo; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Shibata, Takanori*; Nammo, Kesao*; Ueno, Akira; Shinto, Katsuhiro
AIP Conference Proceedings 1869, p.030053_1 - 030053_7, 2017/08
Times Cited Count：5 Percentile：89.08(Physics, Applied)A cesiated RF-driven negative hydrogen ion source was started 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 with two turbo molecular pumps of 1500 L/s for differential pumping. The ion source has been successfully providing the required beam current to the accelerator without any significant issues other than a single-incident antenna failure occurred in October, 2014. Continuous operation for approximately 1,000 h was achieved with a beam current and duty factor of 45 mA and 1.25 % (0.5 msec and 25 Hz), respectively. In this paper, we will present the some operation parameters and the beam stability through the long-term user operation.
ion source; Optimization studiesUeno, Akira
New Journal of Physics (Internet), 19(1), p.015004_1 - 015004_15, 2017/01
Times Cited Count：12 Percentile：64.28(Physics, Multidisciplinary)In order to satisfy the increasing intensity requirements of high-energy and high-intensity proton accelerators for an H
ion beam with small transverse normalized rms emittances of around 0.25 mm
mrad, diverse parameters possibly reducing the emittances were optimised. Such as the plasma electrode shape and temperature, the radio-frequency (RF) matching network for the igniter plasma, the filter-field strength and distribution, the strength of the axial magnetic field around the beam extraction hole, the cesiasion procedure and the cesium (Cs) density, impurity elements, and so on, were optimized with H ion sources for the Japan Proton Accelerator Research Complex (J-PARC). By optimizing each parameter step by step, the J-PARC cesiated RF-driven H ion source successfully produced the world brightest class beam with 95% beam transverse normalized rms emittances of 0.24 mmmrad and an intensity of 66 mA.
