SRF2023 - List of Authors (Ito, H.)

Paper	Title	Page
MOPMB033	Efforts to Suppress Field Emission in SRF Cavities at KEK	167
	M. Omet, H. Araki, T. Dohmae, H. Ito, R. Katayama, K. Umemori, Y. Yamamoto KEK, Ibaraki, Japan
	Our main objective is to achieve as high as possible quality factors Q₀ and maximal accelerating voltages E_acc within 1.3 GHz superconducting radio frequency (SRF) cavities. Beside an adequate surface treatment, key to achieve good performance is a proper assembly in the clean room prior cavity testing or operation. In this contribution we present the methods and results of our efforts to get a better understanding of our clean room environment and the particulate generation caused during the assembly work. Furthermore, we present the measures taken to suppress filed emission, followed by an analysis of vertical test results of the last six years.
	Poster MOPMB033 [1.532 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB033
About •	Received ※ 14 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUIXA03	Surface Resistance and Trapped Flux Sensitivity as Function of Baking Temperature
	H. Ito, H. Araki, K. Umemori KEK, Ibaraki, Japan
	We have investigated the influence of furnace baking at various baking temperatures on Q-value and trapped flux sensitivity. We find that mid-temperature baking is a promising process for obtaining a high Q-value, but it results in a high flux sensitivity. In particular, 300°C baking results in extremely high Q-value and sensitivity. Instead, 250°C baking is found to be a more effective process than 300°C baking for accelerator applications, as it can reach a higher accelerating gradient while keeping a high Q-value and a lower sensitivity. In addition, we find that 200°C baking can reach a higher Q-value at a high accelerating gradient e.g. 35 MV/m compared to 120°C 48 h baking that is applied to the cavity normally.
	Slides TUIXA03 [32.219 MB]
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TUPTB014	Development of Nb₃Sn Coating System and RF Measurement Results at KEK	414
	H. Ito, H. Sakai, K. Umemori, T. Yamada KEK, Ibaraki, Japan K. Takahashi Sokendai, Ibaraki, Japan
	We have constructed an Nb₃Sn cavity coating system based on the Sn vapor diffusion method. After the construction, improvement of our coating system and environment has been conducted through sample and cavity coating research. Our cavity achieves a Q-value above 1E10 at 4 K after improvement. We will report on the detail of improvement on our coating system and RF measurement results of single-cell Nb₃Sn cavity.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB014
About •	Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTB018	MgB₂ Coating Parameter Optimization Using a 1.3-GHz 1-Cell Cavity	425
	T. Tajima, T.P. Grumstrup, J.D. Thompson LANL, Los Alamos, New Mexico, USA H. Ito, E. Kako, T. Okada, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	Funding: DOE Office of Science, Office of High Energy Physics We have started parameter optimization for the coating of MgB₂ using a 1-cell 1.3-GHz elliptical cavity with holes for small samples. Our coating method is based on a 2-step technique, i.e., coat a B layer by flowing diborane gas in the first step and react it with Mg vapor in the 2nd step. Three 6 mm x 6 mm B-coated flat samples are attached at inlet, outlet beam pipes, and at a cell equator and reacted with Mg vapor with different parameters and conditions. We started to see the superconducting transitions on samples but Tc is still lower than our goal of >35 K. We will present our current status of B-Mg reaction tests and construction of B coating system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB018
About •	Received ※ 06 July 2023 — Revised ※ 26 July 2023 — Accepted ※ 02 September 2023 — Issue date ※ 03 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEIXA04	Development of the Directly-Sliced Niobium Material for High Performance SRF Cavities	634
	A. Kumar, H. Araki, T. Dohmae, H. Ito, T. Saeki, K. Umemori, A. Yamamoto, M. Yamanaka KEK, Ibaraki, Japan A. Yamamoto CERN, Meyrin, Switzerland
	For the purpose of cost reduction for the ILC, KEK has been conducting R&D on direct sliced Nb materials such as large grain and medium grain Nb. Single-cell, 3-cell, and 9-cell cavities have been manufactured, and each has demonstrated a high-performance accelerating gradient exceeding 35 MV/m. The results of applying high-Q/high-G recipes, such as two-step baking and furnace baking to these cavities are also shown. Moreover, mechanical tests have been carried out for the beforementioned materials to evaluate their strength for application to the High-Pressure Gas Safety Law. The status of development of these large grain and Medium grain Nb will be presented.
	Slides WEIXA04 [3.773 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA04
About •	Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 12 July 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Efforts to Suppress Field Emission in SRF Cavities at KEK

167

M. Omet, H. Araki, T. Dohmae, H. Ito, R. Katayama, K. Umemori, Y. Yamamoto
KEK, Ibaraki, Japan

Our main objective is to achieve as high as possible quality factors Q₀ and maximal accelerating voltages E_acc within 1.3 GHz superconducting radio frequency (SRF) cavities. Beside an adequate surface treatment, key to achieve good performance is a proper assembly in the clean room prior cavity testing or operation. In this contribution we present the methods and results of our efforts to get a better understanding of our clean room environment and the particulate generation caused during the assembly work. Furthermore, we present the measures taken to suppress filed emission, followed by an analysis of vertical test results of the last six years.

Poster MOPMB033 [1.532 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB033

About •

Received ※ 14 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023

Cite •

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

TUIXA03

Surface Resistance and Trapped Flux Sensitivity as Function of Baking Temperature

H. Ito, H. Araki, K. Umemori
KEK, Ibaraki, Japan

We have investigated the influence of furnace baking at various baking temperatures on Q-value and trapped flux sensitivity. We find that mid-temperature baking is a promising process for obtaining a high Q-value, but it results in a high flux sensitivity. In particular, 300°C baking results in extremely high Q-value and sensitivity. Instead, 250°C baking is found to be a more effective process than 300°C baking for accelerator applications, as it can reach a higher accelerating gradient while keeping a high Q-value and a lower sensitivity. In addition, we find that 200°C baking can reach a higher Q-value at a high accelerating gradient e.g. 35 MV/m compared to 120°C 48 h baking that is applied to the cavity normally.

Slides TUIXA03 [32.219 MB]

Cite •

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

TUPTB014

Development of Nb₃Sn Coating System and RF Measurement Results at KEK

414

H. Ito, H. Sakai, K. Umemori, T. Yamada
KEK, Ibaraki, Japan
K. Takahashi
Sokendai, Ibaraki, Japan

We have constructed an Nb₃Sn cavity coating system based on the Sn vapor diffusion method. After the construction, improvement of our coating system and environment has been conducted through sample and cavity coating research. Our cavity achieves a Q-value above 1E10 at 4 K after improvement. We will report on the detail of improvement on our coating system and RF measurement results of single-cell Nb₃Sn cavity.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB014

About •

Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 28 June 2023

Cite •

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

TUPTB018

MgB₂ Coating Parameter Optimization Using a 1.3-GHz 1-Cell Cavity

425

T. Tajima, T.P. Grumstrup, J.D. Thompson
LANL, Los Alamos, New Mexico, USA
H. Ito, E. Kako, T. Okada, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

Funding: DOE Office of Science, Office of High Energy Physics
We have started parameter optimization for the coating of MgB₂ using a 1-cell 1.3-GHz elliptical cavity with holes for small samples. Our coating method is based on a 2-step technique, i.e., coat a B layer by flowing diborane gas in the first step and react it with Mg vapor in the 2nd step. Three 6 mm x 6 mm B-coated flat samples are attached at inlet, outlet beam pipes, and at a cell equator and reacted with Mg vapor with different parameters and conditions. We started to see the superconducting transitions on samples but Tc is still lower than our goal of >35 K. We will present our current status of B-Mg reaction tests and construction of B coating system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB018

About •

Received ※ 06 July 2023 — Revised ※ 26 July 2023 — Accepted ※ 02 September 2023 — Issue date ※ 03 September 2023

Cite •

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

WEIXA04

Development of the Directly-Sliced Niobium Material for High Performance SRF Cavities

634

A. Kumar, H. Araki, T. Dohmae, H. Ito, T. Saeki, K. Umemori, A. Yamamoto, M. Yamanaka
KEK, Ibaraki, Japan
A. Yamamoto
CERN, Meyrin, Switzerland

For the purpose of cost reduction for the ILC, KEK has been conducting R&D on direct sliced Nb materials such as large grain and medium grain Nb. Single-cell, 3-cell, and 9-cell cavities have been manufactured, and each has demonstrated a high-performance accelerating gradient exceeding 35 MV/m. The results of applying high-Q/high-G recipes, such as two-step baking and furnace baking to these cavities are also shown. Moreover, mechanical tests have been carried out for the beforementioned materials to evaluate their strength for application to the High-Pressure Gas Safety Law. The status of development of these large grain and Medium grain Nb will be presented.

Slides WEIXA04 [3.773 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA04

About •

Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 12 July 2023

Cite •

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