eeFACT2018 - List of Authors (Fukuma, H.)

Paper	Title	Page
TUYAA04	Study to Mitigate Electron Cloud Effect in SuperKEKB	95
	Y. Suetsugu, H. Fukuma, K. Ohmi, K. Shibata, M. Tobiyama KEK, Ibaraki, Japan
	During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04
About •	paper received ※ 27 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPBB05	Beam Instrumentation at SuperKEKB	169
	G.M. Mitsuka, M. Arinaga, J.W. Flanagan, H. Fukuma, H. Ikeda, H. Ishii, S.H. Iwabuchi, K. Mori, E. Mulyani, M. Tejima, M. Tobiyama KEK, Ibaraki, Japan G. Bonvicini Wayne State University, Detroit, Michigan, USA E. Mulyani Sokendai, Ibaraki, Japan G.S. Varner University of Hawaii, Honolulu,, USA
	Phase 2 commissioning of the SuperKEKB electron-positron collider has been performed with final focus optics from February 8 to July 17, 2018. The main aims of Phase 2 commissioning were to verify the novel nano-beam collision scheme and achieve the machine luminosity O(10³⁴ cm^-2s^-1). The beam instruments including the bunch-by-bunch feedback and orbit feedback systems, which are central to the beam diagnostics at SuperKEKB, were successfully operated throughout Phase 2. In this talk, we will present the commissioning results focusing on beam diagnostics and show prospects for the final phase of commissioning from next spring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPBB05
About •	paper received ※ 26 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Study to Mitigate Electron Cloud Effect in SuperKEKB

95

Y. Suetsugu, H. Fukuma, K. Ohmi, K. Shibata, M. Tobiyama
KEK, Ibaraki, Japan

During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04

About •

paper received ※ 27 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

TUPBB05

Beam Instrumentation at SuperKEKB

169

G.M. Mitsuka, M. Arinaga, J.W. Flanagan, H. Fukuma, H. Ikeda, H. Ishii, S.H. Iwabuchi, K. Mori, E. Mulyani, M. Tejima, M. Tobiyama
KEK, Ibaraki, Japan
G. Bonvicini
Wayne State University, Detroit, Michigan, USA
E. Mulyani
Sokendai, Ibaraki, Japan
G.S. Varner
University of Hawaii, Honolulu,, USA

Phase 2 commissioning of the SuperKEKB electron-positron collider has been performed with final focus optics from February 8 to July 17, 2018. The main aims of Phase 2 commissioning were to verify the novel nano-beam collision scheme and achieve the machine luminosity O(10³⁴ cm^-2s^-1). The beam instruments including the bunch-by-bunch feedback and orbit feedback systems, which are central to the beam diagnostics at SuperKEKB, were successfully operated throughout Phase 2. In this talk, we will present the commissioning results focusing on beam diagnostics and show prospects for the final phase of commissioning from next spring.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPBB05

About •

paper received ※ 26 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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