eeFACT2018 - List of Authors (Kobayashi, T.)

Paper	Title	Page
TUPAB07	Commissioning of Positron Damping Ring and the Beam Transport for SuperKEKB	152
	N. Iida, Y. Funakoshi, H. Ikeda, T. Ishibashi, H. Kaji, T. Kamitani, M. Kikuchi, T. Kobayashi, H. Koiso, F. Miyahara, T. Mori, Y. Ohnishi, Y. Seimiya, H. Sugimoto, H. Sugimura, R. Ueki, Y. Yano, D. Zhou KEK, Ibaraki, Japan
	The Positron Damping Ring (DR) for SuperKEKB successfully started its operation in February 2018, and the commissioning was continued until the end of SuperKEKB Phase 2 in July without serious troubles. This paper describes achievements of the beam commissioning of injection and extraction lines (LTR and RTL) between the LINAC and DR. In the LTR commissioning, the positron beam with high emittance, wide energy spread, and high charge were transported and injected into the DR. In the RTL commissioning, special cares were necessary to preserve the low emittance. The observed emittance growth in the RTL was not a problem for Phase 2, but it should be resolved in the coming Phase 3. In this paper, brief results of the commissioning of the DR is also reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB07
About •	paper received ※ 20 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEYAA03	SRF System for KEKB and SuperKEKB	256
	K. Nakanishi, T. Kobayashi, M. Nishiwaki KEK, Ibaraki, Japan K. Hirosawa Sokendai, Ibaraki, Japan
	Eight superconducting accelerating cavities were operated for more than ten years at the KEKB. Commisioning operation of SuperKEKB is ongoing and those cavities are also used to accelerate the electron beam of 2.6 A. There are some issues to address the large beam current and to realize stable operation. One issue is a large HOM power of 37 kW expected to be induced in each cavity module. To cope with the HOM power issue, we have installed an additional HOM damper to the downstream of the cavity module. Another issue is degradation of Q values of the cavities during the ten years operation. Cause of the degradation was particle contamination. To clean the cavity surface, high pressure rinsing (HPR) is an effective way. Therefore we have developed a horizontal HPR. In this method, a nozzle for water jet is inserted horizontally into the cavity module without disassembly of the cavity. We applied the horizontal HPR to our degraded cavities. The RF performances of those cavities have been successfully recovered. In this report, present status of our cavity will be presented. Additionally, LLRF control issues for SuperKEKB will be introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEYAA03
About •	paper received ※ 12 October 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

Commissioning of Positron Damping Ring and the Beam Transport for SuperKEKB

152

N. Iida, Y. Funakoshi, H. Ikeda, T. Ishibashi, H. Kaji, T. Kamitani, M. Kikuchi, T. Kobayashi, H. Koiso, F. Miyahara, T. Mori, Y. Ohnishi, Y. Seimiya, H. Sugimoto, H. Sugimura, R. Ueki, Y. Yano, D. Zhou
KEK, Ibaraki, Japan

The Positron Damping Ring (DR) for SuperKEKB successfully started its operation in February 2018, and the commissioning was continued until the end of SuperKEKB Phase 2 in July without serious troubles. This paper describes achievements of the beam commissioning of injection and extraction lines (LTR and RTL) between the LINAC and DR. In the LTR commissioning, the positron beam with high emittance, wide energy spread, and high charge were transported and injected into the DR. In the RTL commissioning, special cares were necessary to preserve the low emittance. The observed emittance growth in the RTL was not a problem for Phase 2, but it should be resolved in the coming Phase 3. In this paper, brief results of the commissioning of the DR is also reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB07

About •

paper received ※ 20 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

WEYAA03

SRF System for KEKB and SuperKEKB

256

K. Nakanishi, T. Kobayashi, M. Nishiwaki
KEK, Ibaraki, Japan
K. Hirosawa
Sokendai, Ibaraki, Japan

Eight superconducting accelerating cavities were operated for more than ten years at the KEKB. Commisioning operation of SuperKEKB is ongoing and those cavities are also used to accelerate the electron beam of 2.6 A. There are some issues to address the large beam current and to realize stable operation. One issue is a large HOM power of 37 kW expected to be induced in each cavity module. To cope with the HOM power issue, we have installed an additional HOM damper to the downstream of the cavity module. Another issue is degradation of Q values of the cavities during the ten years operation. Cause of the degradation was particle contamination. To clean the cavity surface, high pressure rinsing (HPR) is an effective way. Therefore we have developed a horizontal HPR. In this method, a nozzle for water jet is inserted horizontally into the cavity module without disassembly of the cavity. We applied the horizontal HPR to our degraded cavities. The RF performances of those cavities have been successfully recovered. In this report, present status of our cavity will be presented. Additionally, LLRF control issues for SuperKEKB will be introduced.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEYAA03

About •

paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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