IPAC2018 - List of Authors (Hayashi, K.)

Paper	Title	Page
THPAK031	Suppression of Longitudinal Coupled Bunch Instability by Harmonic Cavity in UVSOR Electron Storage Ring	3280
	A. Mochihashi KIT, Eggenstein-Leopoldshafen, Germany M. Fujimoto, K. Hayashi, M. Katoh UVSOR, Okazaki, Japan J. H. Hasegawa, M. Hosaka, M. Hosaka, Y. Takashima, Y. Takashima Nagoya University, Nagoya, Japan M. Hosaka, Y. Takashima Aichi Synchrotron Radiation Center, Aichi, Japan M. Katoh Sokendai - Okazaki, Okazaki, Aichi, Japan
	In the UVSOR electron storage ring, which is dedicated for a VUV synchrotron radiation light source, a longitudinal coupled bunch instability (LCBI) is observed in multi-bunch operation. To suppress the LCBI, we routinely operate a third harmonic cavity (HCV) in a passive mode. By properly tuning HCV, the instability is almost completely suppressed. Because of the lower beam energy (750 MeV) and brilliant beam emittance (17.5 nm-rad), the Touschek effect becomes severe in the UVSOR. To guarantee enough beam lifetime, we also apply HCV for lengthening the bunch. The suppression of the instability and increasing the beam lifetime are crucial benefits by HCV for the UVSOR. However, not only the origin of the LCBI but also the Landau damping effect by HCV has not been understood systematically yet. We have noticed that one of the HOMs at HCV itself could cause the LCBI and observed the behavior of the instability, which strongly depends on the beam current. From the experiment we have discussed the cause of the instability with the HOM theory. We have also tried to observe synchrotron tune spread and discussed a competition between the Landau damping and the instability growth. Present affiliation of the first auther : Karlsruhe Institute of Technology
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK031
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Paper

Title

Page

Suppression of Longitudinal Coupled Bunch Instability by Harmonic Cavity in UVSOR Electron Storage Ring

3280

A. Mochihashi
KIT, Eggenstein-Leopoldshafen, Germany
M. Fujimoto, K. Hayashi, M. Katoh
UVSOR, Okazaki, Japan
J. H. Hasegawa, M. Hosaka, M. Hosaka, Y. Takashima, Y. Takashima
Nagoya University, Nagoya, Japan
M. Hosaka, Y. Takashima
Aichi Synchrotron Radiation Center, Aichi, Japan
M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan

In the UVSOR electron storage ring, which is dedicated for a VUV synchrotron radiation light source, a longitudinal coupled bunch instability (LCBI) is observed in multi-bunch operation. To suppress the LCBI, we routinely operate a third harmonic cavity (HCV) in a passive mode. By properly tuning HCV, the instability is almost completely suppressed. Because of the lower beam energy (750 MeV) and brilliant beam emittance (17.5 nm-rad), the Touschek effect becomes severe in the UVSOR. To guarantee enough beam lifetime, we also apply HCV for lengthening the bunch. The suppression of the instability and increasing the beam lifetime are crucial benefits by HCV for the UVSOR. However, not only the origin of the LCBI but also the Landau damping effect by HCV has not been understood systematically yet. We have noticed that one of the HOMs at HCV itself could cause the LCBI and observed the behavior of the instability, which strongly depends on the beam current. From the experiment we have discussed the cause of the instability with the HOM theory. We have also tried to observe synchrotron tune spread and discussed a competition between the Landau damping and the instability growth.
Present affiliation of the first auther : Karlsruhe Institute of Technology

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK031

Export •

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