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Journal Articles

First measurement and online monitoring of the stripper foil thinning and pinhole formation to achieve a longer foil lifetime in high-intensity accelerators

Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Harada, Hiroyuki; Tamura, Fumihiko; Yamamoto, Kazami; Yamazaki, Yoshio; Kinsho, Michikazu; Irie, Yoshiro*

Physical Review Accelerators and Beams (Internet), 23(8), p.082801_1 - 082801_13, 2020/08

 Times Cited Count:1 Percentile:35.83(Physics, Nuclear)

Journal Articles

Reduction of the kicker impedance maintaining the performance of present kicker magnet at RCS in J-PARC

Shobuda, Yoshihiro; Irie, Yoshiro*; Takayanagi, Tomohiro; Togashi, Tomohito; Yamamoto, Masanobu; Yamamoto, Kazami

Journal of Physics; Conference Series, 1067, p.062007_1 - 062007_8, 2018/10

 Times Cited Count:1 Percentile:55.23

The present four-terminal kicker at the Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) has the power-saving benefit due to the doubled excitation currents by shorting two-terminals. On the other hand, beam instabilities are excited by the kicker impedances. In this report, we describe a scheme to reduce the kicker impedances using diodes (nonlinear devices) with resistors, while retaining the benefit of the doubled kicker excitation currents.

Journal Articles

Progress status of proof-of-principle demonstration of 400 MeV H$$^{-}$$ laser stripping at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Suganuma, Kazuaki; Yamane, Isao*; Irie, Yoshiro*; Liu, Y.*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.806 - 810, 2018/08

Journal Articles

Development of laser system for a proof-of-principle experiment of laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Inoue, Shunsuke*; Sato, Atsushi*; Suganuma, Kazuaki; Yamane, Isao*; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.811 - 815, 2018/08

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses occur by scattering at the foil. Additionally, the beam collision at the foil may cause the break itself. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. We newly propose and develop a laser stripping injection scheme. At the first step, we propose a proof-of-principle (POP) experiment of the scheme in J-PARC and develop a laser system. In this presentation, we will introduce the laser stripping injection scheme and describe an overview of a POP experiment. We will report a current status of the laser system.

Journal Articles

Status of proof-of-principle demonstration of 400 MeV H- stripping to proton by using only lasers at J-PARC

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Irie, Yoshiro*; Yamane, Isao*; Yoneda, Hitoki*; Michine, Yurina*

Proceedings of 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2018) (Internet), p.422 - 427, 2018/07

Journal Articles

Reducing the beam impedance of the kicker at the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Shobuda, Yoshihiro; Chin, Y. H.*; Hayashi, Naoki; Irie, Yoshiro*; Takayanagi, Tomohiro; Togashi, Tomohito; Toyama, Takeshi*; Yamamoto, Kazami; Yamamoto, Masanobu

Physical Review Accelerators and Beams (Internet), 21(6), p.061003_1 - 161003_15, 2018/06

 Times Cited Count:2 Percentile:29.6(Physics, Nuclear)

no abstracts in English

Journal Articles

A New pulse magnet for the RCS injection shift bump magnet at J-PARC

Takayanagi, Tomohiro; Yamamoto, Kazami; Kamiya, Junichiro; Saha, P. K.; Ueno, Tomoaki*; Horino, Koki*; Kinsho, Michikazu; Irie, Yoshiro*

IEEE Transactions on Applied Superconductivity, 28(3), p.4100505_1 - 4100505_5, 2018/04

Journal Articles

Laser storage ring with high power for realization of laser stripping injection

Harada, Hiroyuki; Yamane, Isao*; Saha, P. K.; Suganuma, Kazuaki; Kinsho, Michikazu; Irie, Yoshiro*; Kato, Shinichi

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.684 - 688, 2017/12

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses are caused by scattering between beams and the foil. Additionally, the collision may occur the foil beak. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. In the J-PARC 3GeV RCS, we newly propose and develop a laser stripping injection scheme. However, it is necessary that laser power is two order higher than latest laser one. To realize this big issue, we develop the laser storage ring, which can provide laser pulse of high repetition rate by recycling one. In this presentation, we will introduce the laser stripping injection scheme and describe the concept of the laser storage ring with high repetition rate and report the current status.

Journal Articles

Status of proof-of-principle experiment for 400 MeV H$$^{-}$$ stripping to protons by using only lasers in the 3-GeV RCS of J-PARC

Saha, P. K.; Harada, Hiroyuki; Yamane, Isao*; Kinsho, Michikazu; Miura, Akihiko; Okabe, Kota; Liu, Y.*; Yoshimoto, Masahiro; Kato, Shinichi; Irie, Yoshiro*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.866 - 870, 2017/12

Journal Articles

Coupled bunch instability and its cure at J-PARC RCS

Shobuda, Yoshihiro; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Takayanagi, Tomohiro; Tamura, Fumihiko; Tani, Norio; Togashi, Tomohito; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2946 - 2949, 2017/05

no abstracts in English

Journal Articles

Theoretical elucidation of space charge effects on the coupled-bunch instability at the 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex

Shobuda, Yoshihiro; Chin, Y. H.*; Saha, P. K.; Hotchi, Hideaki; Harada, Hiroyuki; Irie, Yoshiro*; Tamura, Fumihiko; Tani, Norio; Toyama, Takeshi*; Watanabe, Yasuhiro; et al.

Progress of Theoretical and Experimental Physics (Internet), 2017(1), p.013G01_1 - 013G01_39, 2017/01

AA2016-0375.pdf:3.07MB

 Times Cited Count:10 Percentile:69(Physics, Multidisciplinary)

The Rapid Cycling Synchrotron (RCS), whose beam energy ranges from 400 MeV to 3 GeV and which is located in the Japan Proton Accelerator Research Complex, is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Contrary to conventional understanding, we have succeeded to accelerate a 1-MW equivalent beam. The machine has some interesting features: for instance, the beam tends to be unstable for the smaller transverse beam size, the beam is stabilized by increasing the peak current ${it etc}$. Space charge effects play an important role in the beam instability at the RCS. In this study, a new theory has been developed to calculate the beam growth rate with the head-tail and coupled-bunch modes ($$m,mu$$) while taking space charge effects into account. The theory sufficiently explains the distinctive features of the beam instabilities at the RCS.

Journal Articles

Laser storage ring with high power for realization of laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yamane, Isao*; Kato, Shinichi; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.983 - 986, 2016/11

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses are caused by scattering between beams and the foil. Additionally, the collision may occur the foil beak. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. In the J-PARC 3GeV RCS, we newly propose and develop a laser stripping injection scheme However, it is necessary that laser power is two order higher than latest laser one. To realize this big issue, we develop the laser storage ring, which can provide laser pulse of high repetition rate by recycling one. In this presentation, we will introduce the laser stripping injection scheme and describe the concept of the laser storage ring with high repetition rate.

Journal Articles

An Experimental plan for 400 MeV H$$^{-}$$ stripping to proton by using only lasers in the J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Kato, Shinichi; Kinsho, Michikazu; Irie, Yoshiro*; Yamane, Isao*

Proceedings of 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2016) (Internet), p.310 - 314, 2016/08

Journal Articles

Analytical estimation of the field modulation during the injection period of the 3 GeV RCS in J-PARC

Shobuda, Yoshihiro; Irie, Yoshiro*

JPS Conference Proceedings (Internet), 8, p.012003_1 - 012003_6, 2015/09

Journal Articles

Measurement of continuous degradation of a stripper foil during ths operation with 300 kW beam power in the 3-GeV RCS of J-PARC

Saha, P. K.; Yoshimoto, Masahiro; Hotchi, Hideaki; Harada, Hiroyuki; Okabe, Kota; Yamazaki, Yoshio; Kinsho, Michikazu; Irie, Yoshiro*

Journal of Radioanalytical and Nuclear Chemistry, 305(3), p.851 - 857, 2015/09

 Times Cited Count:1 Percentile:12.03(Chemistry, Analytical)

Journal Articles

Maintenance of radio-activated stripper foils in the 3 GeV RCS of J-PARC

Yoshimoto, Masahiro; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Sugai, Isao*; Irie, Yoshiro*

Journal of Radioanalytical and Nuclear Chemistry, 305(3), p.865 - 873, 2015/09

 Times Cited Count:0 Percentile:0.01(Chemistry, Analytical)

In the 3-GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted thick Hybrid type Boron-doped Carbon (HBC) stripper foil for the multi-turn H$$^{-}$$ charge-exchange injection. The HBC foil has a great advantage of its longer lifetime against high irradiation. Until now, deformation of the HBC foil is observed, but has not broken during 6 months user operation. However there are high residual dose in the RCS injection area. The highest residual dose is observed at the downstream of titanium chamber flange where the stripper foil is placed. The residual dose was increased with the LINAC energy upgrade from 181 MeV to 400 MeV. It shows that secondary neutrons and protons generated by nuclear reactions in the stripper foil at high energy and high power beam irradiation are the major sources for high residual dose at the injection area. The radio-activation of the stripper foil itself is an intrinsic problem and thus maintenance scenario of the stripper foil at the highly-dosed environment is one of the most important issues for the high intensity accelerators. In the J-PARC RCS, the foil exchange devices were improved according to the new maintenance scenario which aims to keep radiation exposure to staffs as low as possible and to reduce the risk of the radioactive foils break up or disperse. In addition, various analyses of the irradiated stripper foils can be carried out if the foils can be retrieved from the tunnel without breaking.

Journal Articles

New injection bump power supply of the J-PARC RCS

Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki; Tobita, Norimitsu; Hayashi, Naoki; Kinsho, Michikazu; Irie, Yoshiro*; Okabe, Kota; Tani, Norio; Naito, Shingo*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1169 - 1174, 2015/09

The new injection bump power supply for the shift bump magnet of the beam injection sub-systems at the J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid Cycling Synchrotron) has been developed and manufactured. The power capacity of the new power supply was more than doubled with the injection beam energy upgrading of the LINAC (Linear Accelerator) from 181 MeV to 400 MeV. Furthermore, the low ripple noise on the output current was required to prevent the resonance of the RF shield loop at the ceramic duct with the excitation magnetic field. The power supply newly adopted a capacitor commutation method to form the trapezoid waveform pattern (bump waveform). This paper reports characteristic about the new power supply.

Journal Articles

Preliminary studies of laser-assisted H$$^{-}$$ stripping at 400 MeV

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Maruta, Tomofumi*; Okabe, Kota; Yoshimoto, Masahiro; Irie, Yoshiro*; Gorlov, T.*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.3795 - 3797, 2015/06

Journal Articles

New injection bump power supply of the J-PARC RCS

Takayanagi, Tomohiro; Hayashi, Naoki; Ueno, Tomoaki*; Horino, Koki; Okabe, Kota; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2908 - 2910, 2015/06

The new injection bump power supply for the shift bump (SB) magnet of the beam injection system at the J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid-Cycling Synchrotron) has been developed and manufactured. The power capacity of the new power supply demand doubling with the injection beam energy upgrading of the LIANC (Linear Accelerator) from 181 MeV to 400 MeV. Furthermore, the low ripple noise on the output current was required to prevent the occurrence of the resonation between the excitation magnetic field and the RF shield loop covered the ceramics duct at the magnet. The power supply newly adopted a capacitor commutation method to form the trapezoid waveform pattern (bump waveform). This paper reports characteristic about the new shift bump power supply.

Journal Articles

Measurement of 181 MeV H$$^{-}$$ ions stripping cross-sections by carbon stripper foil

Saha, P. K.; Yoshimoto, Masahiro; Yamazaki, Yoshio; Hotchi, Hideaki; Harada, Hiroyuki; Okabe, Kota; Kinsho, Michikazu; Irie, Yoshiro*

Nuclear Instruments and Methods in Physics Research A, 776, p.87 - 93, 2015/03

 Times Cited Count:6 Percentile:54.79(Instruments & Instrumentation)

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