eeFACT2018 - List of Authors (Nakanishi, K.)

Paper	Title	Page
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
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WEPAB04	KEKB/SuperKEKB Cryogenics Operation	276
	K. Nakanishi, K. Hara, T. Honma, K. Hosoyama, M.K. Kawai, Y. Kojima, Y. Morita, H. Nakai, N. Ohuchi, H. Shimizu KEK, Ibaraki, Japan T. Endo, T. Kanekiyo Hitachi Plant Mechanics Co,.Ltd., Kudamatsu city, Japan
	KEKB/SuperKEKB cryogenics operation will be introduced. KEKB was built in the tunnel of the TRISTAN accelerator. The TRISTAN accelerator was operated from 1986 to 1995. The superconducting acceleration cavities were installed in 1988 to increase the beam energy. The cryogenic system for superconducting cavities was also established simultaneously. In 1989 superconducting cavities were added, and cryogenic systems were also enhanced from 4kW to 6.5kW. KEKB took over many facilities from TRISTAN. The cryogenic system for superconducting cavities is one of them. This old refrigerator is used also in SuperKEKB. In operation of the cryogenic system, it is necessary to cool down the equipment from room temperature. In KEKB, its cooling rate of cavities are limited to 2.5~3K/h. In the steady state, the pressure and the liquid level in the superconducting cavity cryomodule should be kept constant. To keep the condition in the cryomodule stably, the sum of the heat generated by RF and the heater is controlled as constant. In KEKB/SuperKEKB, superconducting magnets are also used. They have their own refrigerator. In the workshop, they are also introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEPAB04
About •	paper received ※ 24 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

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)

WEPAB04

KEKB/SuperKEKB Cryogenics Operation

276

K. Nakanishi, K. Hara, T. Honma, K. Hosoyama, M.K. Kawai, Y. Kojima, Y. Morita, H. Nakai, N. Ohuchi, H. Shimizu
KEK, Ibaraki, Japan
T. Endo, T. Kanekiyo
Hitachi Plant Mechanics Co,.Ltd., Kudamatsu city, Japan

KEKB/SuperKEKB cryogenics operation will be introduced. KEKB was built in the tunnel of the TRISTAN accelerator. The TRISTAN accelerator was operated from 1986 to 1995. The superconducting acceleration cavities were installed in 1988 to increase the beam energy. The cryogenic system for superconducting cavities was also established simultaneously. In 1989 superconducting cavities were added, and cryogenic systems were also enhanced from 4kW to 6.5kW. KEKB took over many facilities from TRISTAN. The cryogenic system for superconducting cavities is one of them. This old refrigerator is used also in SuperKEKB. In operation of the cryogenic system, it is necessary to cool down the equipment from room temperature. In KEKB, its cooling rate of cavities are limited to 2.5~3K/h. In the steady state, the pressure and the liquid level in the superconducting cavity cryomodule should be kept constant. To keep the condition in the cryomodule stably, the sum of the heat generated by RF and the heater is controlled as constant. In KEKB/SuperKEKB, superconducting magnets are also used. They have their own refrigerator. In the workshop, they are also introduced.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEPAB04

About •

paper received ※ 24 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)