SRF2017 - List of Authors (Ueki, R.)

Paper	Title	Page
MOPB061	Quality Control of Copper Plating in STF-2 Input Power Couplers	186
	E. Kako, R. Ueki KEK, Ibaraki, Japan K. Hiroaki, J. Taguchi Nomura Plating Co, Ltd., Osaka, Japan K. Okihira, K. Sennyu MHI, Hiroshima, Japan F. Saito, H. Umezawa Tokyo Denkai Co., Ltd., Tokyo, Japan O. Yushiro Toshiba Electron Tubes & Devices Co., Ltd, Tokyo, Japan
	Purity of thin copper plating using in input power couplers for superconducting cavities is one of important characteristics for considering thermal losses at low temperature. Various samples of thin copper plating on stainless sheets was fabricated by three companies with their own plating techniques. The RRR values of the samples with different thickness of copper plating were compared in the condition before and after heat treatment at 800oC in a brazing furnace. Deterioration of the RRR was observed in all of samples after heat treatment. The results of the RRR measurements and sample analysis of impurities will be reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB061
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TUPB028	Improvement of Magnetic Condition for KEK-STF Vertical Test Facility Toward High-Q Study	444
	K. Umemori, T. Dohmae, E. Kako, T. Konomi, T. Kubo, M. Masuzawa, G.-T. Park, A. Terashima, K. Tsuchiya, R. Ueki KEK, Ibaraki, Japan T. Okada Sokendai, Ibaraki, Japan
	Improvement of unloaded Q-values of SRF cavities are important to reduce surface loss of cavity and heat loads of He refrigerators. R&D activities have been developed worldwide. We also started work toward high-Q, but soon realized that magnetic condition of KEK-STF vertical test facility was not good enough to carry out high-Q measurements. First, magnetized components were searched. Shafts to move variable coupler were found to be most magnetized one and exceed more than 1 Gauss. Magnetized components were exchanged to non-magnetized one. In order to further reduce remnant magnetic field, a solenoid coil was prepared and used to cancel it. To suppress flux trapping, a heater was located around an upper beampipe of cavity and made thermal gradient. Owing to these efforts, Q-value of more than 1x10¹¹ can be measured with a condition of residual resistance of ~3 nΩ. Clear flux expulsion signal can be also observed. In this presentation, we report about efforts to reduce ambient magnetic field and to realize high-Q measurements. Results of vertical tests, including flux expulsion measurements, are also presented.
	Poster TUPB028 [1.961 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB028
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Quality Control of Copper Plating in STF-2 Input Power Couplers

186

E. Kako, R. Ueki
KEK, Ibaraki, Japan
K. Hiroaki, J. Taguchi
Nomura Plating Co, Ltd., Osaka, Japan
K. Okihira, K. Sennyu
MHI, Hiroshima, Japan
F. Saito, H. Umezawa
Tokyo Denkai Co., Ltd., Tokyo, Japan
O. Yushiro
Toshiba Electron Tubes & Devices Co., Ltd, Tokyo, Japan

Purity of thin copper plating using in input power couplers for superconducting cavities is one of important characteristics for considering thermal losses at low temperature. Various samples of thin copper plating on stainless sheets was fabricated by three companies with their own plating techniques. The RRR values of the samples with different thickness of copper plating were compared in the condition before and after heat treatment at 800oC in a brazing furnace. Deterioration of the RRR was observed in all of samples after heat treatment. The results of the RRR measurements and sample analysis of impurities will be reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB061

Export •

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

TUPB028

Improvement of Magnetic Condition for KEK-STF Vertical Test Facility Toward High-Q Study

444

K. Umemori, T. Dohmae, E. Kako, T. Konomi, T. Kubo, M. Masuzawa, G.-T. Park, A. Terashima, K. Tsuchiya, R. Ueki
KEK, Ibaraki, Japan
T. Okada
Sokendai, Ibaraki, Japan

Improvement of unloaded Q-values of SRF cavities are important to reduce surface loss of cavity and heat loads of He refrigerators. R&D activities have been developed worldwide. We also started work toward high-Q, but soon realized that magnetic condition of KEK-STF vertical test facility was not good enough to carry out high-Q measurements. First, magnetized components were searched. Shafts to move variable coupler were found to be most magnetized one and exceed more than 1 Gauss. Magnetized components were exchanged to non-magnetized one. In order to further reduce remnant magnetic field, a solenoid coil was prepared and used to cancel it. To suppress flux trapping, a heater was located around an upper beampipe of cavity and made thermal gradient. Owing to these efforts, Q-value of more than 1x10¹¹ can be measured with a condition of residual resistance of ~3 nΩ. Clear flux expulsion signal can be also observed. In this presentation, we report about efforts to reduce ambient magnetic field and to realize high-Q measurements. Results of vertical tests, including flux expulsion measurements, are also presented.

Poster TUPB028 [1.961 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB028

Export •

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