IPAC2018 - List of Authors (Saha, P.K.)

Paper	Title	Page
TUXGBF4	ORBIT Simulation, Measurement and Mitigation of Transverse Beam Instability in the Presence of Strong Space Charge in the 3-GeV RCS of J-PARC	620
	P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse impedance of eight extraction pulse kicker magnets (KM) is extremely strong source of transverse beam instability in the 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC. To realize the designed 1 MW beam power, collective beam dynamics with including the space charge effect for the coupled bunch instabilities excited by the KM impedance and associated measures were studied by incorporating all realistic time-dependent machine parameters in the ORBIT 3-D particle tracking code. The simulation results were all reproduced by measurements and, as a consequence, an acceleration of 1 MW beam power has been successfully demonstrated. In order to maintain variation of the RCS parameters required for multi-user operation, realistic measures for beam instability mitigation were proposed and also been successfully implemented in reality. To further increase the RCS beam power, beam stability issues and possible measures beyond 1 MW beam power are also considered.
	Slides TUXGBF4 [2.241 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF4
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TUPAL018	Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS	1041
	H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto JAEA/J-PARC, Tokai-mura, Japan
	J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL018
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TUPAL020	Recent Status of J-PARC Rapid Cycling Synchrotron	1045
	K. Yamamoto, P.K. Saha JAEA/J-PARC, Tokai-mura, Japan
	The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1 % cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, we carried out the beam study to achieve high power beam operation. Moreover, we also maintain the accelerator components to keep a steady operation. We report present status of the J-PARC RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL020
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TUPAL021	Evaluation of Activated Nuclides Due to Secondary Particles Produced in Stripper Foil in J-PARC RCS	1048
	M. Yoshimoto, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, K. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	Multi-turn charge-exchange beam injection is key technique to achieve the high intensity proton beam accelerators. In the J-PARC RCS, 400MeV H⁻ beams from the LINAC are converted to H⁺ beam with the stripper foils, and then injected into the ring. The stripper foil is irradiated by not only the injecting H⁻ beams but also the circulating H⁺ beams. The high energy and high power beam irradiation into the foil induces the nuclear reactions, and generated secondary neutrons and protons. These secondary particles causes high residual does around the stripper foil. Now, to identify species of secondary particles and to identify energies and emission angles, activation analysis method using the sample pieces is considered. In this presentation, we report the result of the evaluation of this activation analysis with PHITS codes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL021
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WEPAL022	Operating Experience of Water Cooling System in the J-PARC LINAC and RCS	2203
	K. Suganuma, K. Fujirai, M. Kinsho, P.K. Saha, Y. Yamazaki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The cooling system for the J-PARC LINAC and RCS uses a total of 25 circulation pumps to cool the accelerator devices. In February 2017, we experienced damage of circulation pumps due to low flow rate, and started the development of an abnormality detection system concentrating on the vibration measurements of the circulation pumps. In this report, the vibration measurement results of the coolant circulation pumps and the development status of abnormality detection through multivariate analysis using vibration values are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL022
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Paper

Title

Page

ORBIT Simulation, Measurement and Mitigation of Transverse Beam Instability in the Presence of Strong Space Charge in the 3-GeV RCS of J-PARC

620

P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The transverse impedance of eight extraction pulse kicker magnets (KM) is extremely strong source of transverse beam instability in the 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC. To realize the designed 1 MW beam power, collective beam dynamics with including the space charge effect for the coupled bunch instabilities excited by the KM impedance and associated measures were studied by incorporating all realistic time-dependent machine parameters in the ORBIT 3-D particle tracking code. The simulation results were all reproduced by measurements and, as a consequence, an acceleration of 1 MW beam power has been successfully demonstrated. In order to maintain variation of the RCS parameters required for multi-user operation, realistic measures for beam instability mitigation were proposed and also been successfully implemented in reality. To further increase the RCS beam power, beam stability issues and possible measures beyond 1 MW beam power are also considered.

Slides TUXGBF4 [2.241 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF4

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL018

Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS

1041

H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan

J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL020

Recent Status of J-PARC Rapid Cycling Synchrotron

1045

K. Yamamoto, P.K. Saha
JAEA/J-PARC, Tokai-mura, Japan

The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1 % cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, we carried out the beam study to achieve high power beam operation. Moreover, we also maintain the accelerator components to keep a steady operation. We report present status of the J-PARC RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL021

Evaluation of Activated Nuclides Due to Secondary Particles Produced in Stripper Foil in J-PARC RCS

1048

M. Yoshimoto, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

Multi-turn charge-exchange beam injection is key technique to achieve the high intensity proton beam accelerators. In the J-PARC RCS, 400MeV H⁻ beams from the LINAC are converted to H⁺ beam with the stripper foils, and then injected into the ring. The stripper foil is irradiated by not only the injecting H⁻ beams but also the circulating H⁺ beams. The high energy and high power beam irradiation into the foil induces the nuclear reactions, and generated secondary neutrons and protons. These secondary particles causes high residual does around the stripper foil. Now, to identify species of secondary particles and to identify energies and emission angles, activation analysis method using the sample pieces is considered. In this presentation, we report the result of the evaluation of this activation analysis with PHITS codes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL022

Operating Experience of Water Cooling System in the J-PARC LINAC and RCS

2203

K. Suganuma, K. Fujirai, M. Kinsho, P.K. Saha, Y. Yamazaki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The cooling system for the J-PARC LINAC and RCS uses a total of 25 circulation pumps to cool the accelerator devices. In February 2017, we experienced damage of circulation pumps due to low flow rate, and started the development of an abnormality detection system concentrating on the vibration measurements of the circulation pumps. In this report, the vibration measurement results of the coolant circulation pumps and the development status of abnormality detection through multivariate analysis using vibration values are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)