SRF2021 - List of Authors (Mitsunobu, S.)

Paper	Title	Page
TUPFAV002	Calibration of SRF Cavity Voltage by Measurement of Synchrotron Frequency in SuperKEKB	376
	M. Nishiwaki, K. Akai, T. Furuya, T. Kobayashi, S. Mitsunobu, Y. Morita, T. Okada KEK, Ibaraki, Japan
	Eight SRF cavity modules, which have been operated in KEKB for more than ten years, are stably operating also in SuperKEKB. As for calibration of the cavity voltage Vc, non-negligible discrepancy was observed between the results obtained from two different methods: one is using external Q value (Q_ext) of pickup ports, and the other is using loaded Q value (QL) of the cavities. The discrepancy comes from inaccuracy of power measurement in high power RF system and uncertainty of the Q_ext or QL values. In order to solve the discrepancy by improving the accuracy of the calibration for each individual cavity, we investigated a method by measuring synchrotron frequency fs of stored beam. With this method, Vc calibration can be performed without affected by inaccuracy of high-power measurement or uncertainty of the Q_ext or QL values. The fs measurement studies were carried out in SuperKEKB. With these studies, Vc calibration was obtained with a high accuracy of about 1%. The results are applied to the SuperKEKB operation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV002
About •	Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 October 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Calibration of SRF Cavity Voltage by Measurement of Synchrotron Frequency in SuperKEKB

376

M. Nishiwaki, K. Akai, T. Furuya, T. Kobayashi, S. Mitsunobu, Y. Morita, T. Okada
KEK, Ibaraki, Japan

Eight SRF cavity modules, which have been operated in KEKB for more than ten years, are stably operating also in SuperKEKB. As for calibration of the cavity voltage Vc, non-negligible discrepancy was observed between the results obtained from two different methods: one is using external Q value (Q_ext) of pickup ports, and the other is using loaded Q value (QL) of the cavities. The discrepancy comes from inaccuracy of power measurement in high power RF system and uncertainty of the Q_ext or QL values. In order to solve the discrepancy by improving the accuracy of the calibration for each individual cavity, we investigated a method by measuring synchrotron frequency fs of stored beam. With this method, Vc calibration can be performed without affected by inaccuracy of high-power measurement or uncertainty of the Q_ext or QL values. The fs measurement studies were carried out in SuperKEKB. With these studies, Vc calibration was obtained with a high accuracy of about 1%. The results are applied to the SuperKEKB operation.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV002

About •

Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 14 October 2021

Cite •

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