IPAC2018 - List of Authors (Hotchi, H.)

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
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)

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)