IBIC2017 - List of Authors (Akai, K.)

Paper	Title	Page
TUPWC05	New RF Feedback System and Simulations for Suppression of Coupled-Bunch Instabilities at SuperKEKB	292
	K. Hirosawa Sokendai, Ibaraki, Japan K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto KEK, Ibaraki, Japan
	SuperKEKB, which is an upgrade of KEKB, is an asymmetrical energy electron positron circular collider located at KEK in Japan. The design currents are 2.6 A (electron) and 3.6 A (positron) in order to achieve the unprecedented high luminosity. Coupled-Bunch Instabilities (CBI) caused by accelerating mode will become serious by large beam current, and then we can no longer keep synchrotron oscillation stable by using an existing KEKB RF system and CBI damper, which can suppress only lowest (m = -1) mode. Therefore we developed a new damper for higher order modes of CBI (m = -2, -3). Characteristics of the new damper were evaluated and the result satisfies our required specifications. As an estimation of the feedback performance for the SuperKEKB operation, we simulated the beam oscillation damping/exciting process with CBI damper. It was found from these result that we need more dampers to suppress the m = -1 mode instability of CBI in addition to KEKB system, since growth rate of the m = -1 mode will be ten times higher than that of KEKB. We will report the detail of an RF feedback system used new dampers and results of time domain simulations of a longitudinal bunch oscillation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TUPWC05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

New RF Feedback System and Simulations for Suppression of Coupled-Bunch Instabilities at SuperKEKB

292

K. Hirosawa
Sokendai, Ibaraki, Japan
K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwaki, S.I. Yoshimoto
KEK, Ibaraki, Japan

SuperKEKB, which is an upgrade of KEKB, is an asymmetrical energy electron positron circular collider located at KEK in Japan. The design currents are 2.6 A (electron) and 3.6 A (positron) in order to achieve the unprecedented high luminosity. Coupled-Bunch Instabilities (CBI) caused by accelerating mode will become serious by large beam current, and then we can no longer keep synchrotron oscillation stable by using an existing KEKB RF system and CBI damper, which can suppress only lowest (m = -1) mode. Therefore we developed a new damper for higher order modes of CBI (m = -2, -3). Characteristics of the new damper were evaluated and the result satisfies our required specifications. As an estimation of the feedback performance for the SuperKEKB operation, we simulated the beam oscillation damping/exciting process with CBI damper. It was found from these result that we need more dampers to suppress the m = -1 mode instability of CBI in addition to KEKB system, since growth rate of the m = -1 mode will be ten times higher than that of KEKB. We will report the detail of an RF feedback system used new dampers and results of time domain simulations of a longitudinal bunch oscillation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TUPWC05

Export •

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