SRF2021 - List of Authors (Ito, H.)

Paper	Title	Page
SUPCAV008	Design and Construction of Nb₃Sn Vapor Diffusion Coating System at KEK	23
	K. Takahashi, T. Okada Sokendai, Ibaraki, Japan H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	Vapor diffusion Nb₃Sn coating system was developed at KEK. At most 1.3GHz 3-cell cavity can be coat with the coating system. The coating system consists of a coating chamber made of Nb, a vacuum furnace for heating the Nb chamber, and a heating device of Tin in the crucible. The Nb chamber vacuum and the furnace vacuum are isolated to prevent contamination from the furnace. There is a heating device for increasing Tin vapor pressure. In this presentation, the design and construction of the coating system are reported.
	Poster SUPCAV008 [0.986 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV008
About •	Received ※ 21 June 2021 — Accepted ※ 18 November 2021 — Issue date ※ 11 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

SUPCAV009	First Nb₃Sn Coating and Cavity Performance Result at KEK	27
	K. Takahashi, T. Okada Sokendai, Ibaraki, Japan H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori KEK, Ibaraki, Japan
	At KEK, Nb₃Sn vapor diffusion R&D for High-Q has just started. We have performed Nb₃Sn coating on niobium samples and characterized these samples. We optimized the cavity coating parameter from the result of characterized samples. After optimizing the parameter, we have performed Nb₃Sn coating on a TESLA-like single-cell Nb cavity and measured cavity performance in vertical tests. This presentation presents the result of the cavity coating and performance results.
	Poster SUPCAV009 [1.481 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV009
About •	Received ※ 21 June 2021 — Accepted ※ 18 March 2022 — Issue date ※ 16 May 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPCAV006	High-Q/High-G R&D at KEK Using 9-Cell TESLA-Shaped Niobium Cavities	268
	R. Katayama, A. Araki, H. Ito, E. Kako, T. Konomi, S. Michizono, M. Omet, K. Umemori KEK, Ibaraki, Japan
	We will report on the current progress of High-Q/High-G R&D using three 1.3 GHz 9-cell TESLA shape niobium superconducting cavities at the High Energy Accelerator Research Organization (KEK). These cavities are made of bulk niobium of fine grain material with RRR >300 and have been annealed at 900 degrees for 3 hours. The cavity performances were evaluated at the Superconducting RF Test Facility at KEK (KEK-STF) after 2-step bake (70-75°C 4 h + 120°C 48 h), electropolishing at low temperature, and fast cooling procedure were applied to these cavities. In this study, obtained results will be compared with the baseline measurement for the standard recipe at KEK.
	Poster MOPCAV006 [1.880 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV006
About •	Received ※ 22 June 2021 — Revised ※ 14 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 February 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPFAV003	Stable Beam Operation at 33 MV/m in STF-2 Cryomodules at KEK	382
	Y. Yamamoto, M. Akemoto, D.A. Arakawa, A. Araki, S. Araki, A. Aryshev, T. Dohmae, M. Egi, M.K. Fukuda, K. Hara, H. Hayano, Y. Honda, T. Honma, H. Ito, E. Kako, H. Katagiri, R. Katayama, M. Kawamura, N. Kimura, Y. Kojima, Y. Kondou, T. Konomi, M. Masuzawa, T. Matsumoto, S. Michizono, Y. Morikawa, H. Nakai, H. Nakajima, K. Nakanishi, M. Omet, T. Oyama, T. Saeki, H. Sakai, H. Shimizu, S.I. Takahara, R. Ueki, K. Umemori, A. Yamamoto KEK, Ibaraki, Japan S. Aramoto Hiroshima University, Higashi-Hiroshima, Japan M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Z.J. Liptak HU/AdSM, Higashi-Hiroshima, Japan K. Sakaue The University of Tokyo, The School of Engineering, Tokyo, Japan A. Yamamoto CERN, Meyrin, Switzerland
	In STF at KEK, as the operational demonstration of the SRF accelerator for ILC, the STF-2 cryomodules (CM¹⁺CM2a: one and half size CM with 12 cavities) have achieved 33 MV/m as average accelerating gradient with 7 cavities in Mar/2019. After that, one cavity with the lowest performance installed in CM2a was replaced with one N-infused cavity developed for High-Q/High-G R&D between Japan and US. From this April, the beam operation started again and those CMs achieved 33 MV/m as average accelerating gradient with 9 cavities including one N-infused cavity again. This is the very important milestone for ILC. In this report, the detailed results will be presented.
	Poster TUPFAV003 [3.020 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV003
About •	Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 01 November 2021
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPFDV008	Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University	421
	Y. Fuwa JAEA/J-PARC, Tokai-mura, Japan H. Hayano, H. Ito, R. Katayama, T. Kubo, T. Saeki KEK, Ibaraki, Japan Y. Iwashita, Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	We have been developing SRF instrumentations by which the effective lower critical magnetic field H_c1,eff of superconducting-material sample is evaluated through the method of the third-order harmonic voltage measurement mainly for the studies of new SRF thin-film structures. Recently, the quad coil system, which enables us to measure four samples simultaneously in a single batch of an experiment, has been developed. In order to study the creation of thin-film structures inside the SRF cavity, we developed 3-GHz-shaped coupon cavities and an XT-map system for the performance tests of 3 GHz cavities. This article reports the details of these works.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFDV008
About •	Received ※ 01 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 02 April 2022 — Issue date ※ 02 May 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPCAV001	Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: First Results	431
	F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin CEA-DRF-IRFU, France V. Chouhan, Y.I. Ida, K. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki KEK, Ibaraki, Japan G. Jullien CEA-IRFU, Gif-sur-Yvette, France
	Vertical Electro-Polishing (VEP) of elliptical cavities using rotating Ninja cathodes (Marui Company patented technology) has continually been improved since 2012 and successfully applied for 1300MHz multicell ILC-type resonators. The goal of the presented study is to apply this technology to 704 MHz ESS-type resonators with both better Q₀ and accelerating gradients in mind. We intend to demonstrate the superiority of VEP compared to standard Buffer Chemical Polishing (BCP), for possible applications such as MYRRHA accelerator. We describe here the promising results achieved on β=0.86 single-cell cavity after 200 µm uniform removal. The cavity quenched at 27 MV/m without any heat treatment. The surface resistance achieved was less than 5nΩ at 1.8K. Substantial performance improvement is expected after heat treatment of the cavity and additional 20 µm VEP sequence. A cathode for 5-Cell ESS cavity is concomitantly under design stage.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV001
About •	Received ※ 21 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 17 March 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FROFDV01	Systematic Investigation of Mid-T Furnace Baking for High-Q Performance	881
	H. Ito, A. Araki, K. Umemori KEK, Ibaraki, Japan K. Takahashi Sokendai, Ibaraki, Japan
	We report on an investigation of the effect of a new baking process called "furnace baking" on the quality factor. Furnace baking is performed as the final step of the cavity surface treatment; the cavities are heated in a vacuum furnace in a temperature range of 200-800C for 3 h, followed by high-pressure rinsing and radio-frequency measurement. We find the anti-Q-slope for cavities furnace-baked at a temperature range of 250 to 400C and a reduction in the residual resistance for all cavities. In particular, an extremely high Q value of 5·10¹⁰ at 16 MV/m and 2.0 K is obtained for cavities furnace-baked at 300C.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-FROFDV01
About •	Received ※ 21 June 2021 — Accepted ※ 24 February 2022 — Issue date ※ 30 April 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Design and Construction of Nb₃Sn Vapor Diffusion Coating System at KEK

23

K. Takahashi, T. Okada
Sokendai, Ibaraki, Japan
H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

Vapor diffusion Nb₃Sn coating system was developed at KEK. At most 1.3GHz 3-cell cavity can be coat with the coating system. The coating system consists of a coating chamber made of Nb, a vacuum furnace for heating the Nb chamber, and a heating device of Tin in the crucible. The Nb chamber vacuum and the furnace vacuum are isolated to prevent contamination from the furnace. There is a heating device for increasing Tin vapor pressure. In this presentation, the design and construction of the coating system are reported.

Poster SUPCAV008 [0.986 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV008

About •

Received ※ 21 June 2021 — Accepted ※ 18 November 2021 — Issue date ※ 11 April 2022

Cite •

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

SUPCAV009

First Nb₃Sn Coating and Cavity Performance Result at KEK

27

K. Takahashi, T. Okada
Sokendai, Ibaraki, Japan
H. Ito, E. Kako, T. Konomi, H. Sakai, K. Umemori
KEK, Ibaraki, Japan

At KEK, Nb₃Sn vapor diffusion R&D for High-Q has just started. We have performed Nb₃Sn coating on niobium samples and characterized these samples. We optimized the cavity coating parameter from the result of characterized samples. After optimizing the parameter, we have performed Nb₃Sn coating on a TESLA-like single-cell Nb cavity and measured cavity performance in vertical tests. This presentation presents the result of the cavity coating and performance results.

Poster SUPCAV009 [1.481 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPCAV009

About •

Received ※ 21 June 2021 — Accepted ※ 18 March 2022 — Issue date ※ 16 May 2022

Cite •

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

MOPCAV006

High-Q/High-G R&D at KEK Using 9-Cell TESLA-Shaped Niobium Cavities

268

R. Katayama, A. Araki, H. Ito, E. Kako, T. Konomi, S. Michizono, M. Omet, K. Umemori
KEK, Ibaraki, Japan

We will report on the current progress of High-Q/High-G R&D using three 1.3 GHz 9-cell TESLA shape niobium superconducting cavities at the High Energy Accelerator Research Organization (KEK). These cavities are made of bulk niobium of fine grain material with RRR >300 and have been annealed at 900 degrees for 3 hours. The cavity performances were evaluated at the Superconducting RF Test Facility at KEK (KEK-STF) after 2-step bake (70-75°C 4 h + 120°C 48 h), electropolishing at low temperature, and fast cooling procedure were applied to these cavities. In this study, obtained results will be compared with the baseline measurement for the standard recipe at KEK.

Poster MOPCAV006 [1.880 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-MOPCAV006

About •

Received ※ 22 June 2021 — Revised ※ 14 January 2022 — Accepted ※ 22 February 2022 — Issue date ※ 28 February 2022

Cite •

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

TUPFAV003

Stable Beam Operation at 33 MV/m in STF-2 Cryomodules at KEK

382

Y. Yamamoto, M. Akemoto, D.A. Arakawa, A. Araki, S. Araki, A. Aryshev, T. Dohmae, M. Egi, M.K. Fukuda, K. Hara, H. Hayano, Y. Honda, T. Honma, H. Ito, E. Kako, H. Katagiri, R. Katayama, M. Kawamura, N. Kimura, Y. Kojima, Y. Kondou, T. Konomi, M. Masuzawa, T. Matsumoto, S. Michizono, Y. Morikawa, H. Nakai, H. Nakajima, K. Nakanishi, M. Omet, T. Oyama, T. Saeki, H. Sakai, H. Shimizu, S.I. Takahara, R. Ueki, K. Umemori, A. Yamamoto
KEK, Ibaraki, Japan
S. Aramoto
Hiroshima University, Higashi-Hiroshima, Japan
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Z.J. Liptak
HU/AdSM, Higashi-Hiroshima, Japan
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
A. Yamamoto
CERN, Meyrin, Switzerland

In STF at KEK, as the operational demonstration of the SRF accelerator for ILC, the STF-2 cryomodules (CM¹⁺CM2a: one and half size CM with 12 cavities) have achieved 33 MV/m as average accelerating gradient with 7 cavities in Mar/2019. After that, one cavity with the lowest performance installed in CM2a was replaced with one N-infused cavity developed for High-Q/High-G R&D between Japan and US. From this April, the beam operation started again and those CMs achieved 33 MV/m as average accelerating gradient with 9 cavities including one N-infused cavity again. This is the very important milestone for ILC. In this report, the detailed results will be presented.

Poster TUPFAV003 [3.020 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFAV003

About •

Received ※ 21 June 2021 — Revised ※ 11 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 01 November 2021

Cite •

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

TUPFDV008

Instrumentation R&D for the Studies of SRF Thin-Film Structures at KEK and Kyoto University

421

Y. Fuwa
JAEA/J-PARC, Tokai-mura, Japan
H. Hayano, H. Ito, R. Katayama, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
Y. Iwashita, Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

We have been developing SRF instrumentations by which the effective lower critical magnetic field H_c1,eff of superconducting-material sample is evaluated through the method of the third-order harmonic voltage measurement mainly for the studies of new SRF thin-film structures. Recently, the quad coil system, which enables us to measure four samples simultaneously in a single batch of an experiment, has been developed. In order to study the creation of thin-film structures inside the SRF cavity, we developed 3-GHz-shaped coupon cavities and an XT-map system for the performance tests of 3 GHz cavities. This article reports the details of these works.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPFDV008

About •

Received ※ 01 July 2021 — Revised ※ 19 December 2021 — Accepted ※ 02 April 2022 — Issue date ※ 02 May 2022

Cite •

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

TUPCAV001

Vertical Electro-Polishing of 704 MHz Resonators Using Ninja Cathode: First Results

431

F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin
CEA-DRF-IRFU, France
V. Chouhan, Y.I. Ida, K. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki
KEK, Ibaraki, Japan
G. Jullien
CEA-IRFU, Gif-sur-Yvette, France

Vertical Electro-Polishing (VEP) of elliptical cavities using rotating Ninja cathodes (Marui Company patented technology) has continually been improved since 2012 and successfully applied for 1300MHz multicell ILC-type resonators. The goal of the presented study is to apply this technology to 704 MHz ESS-type resonators with both better Q₀ and accelerating gradients in mind. We intend to demonstrate the superiority of VEP compared to standard Buffer Chemical Polishing (BCP), for possible applications such as MYRRHA accelerator. We describe here the promising results achieved on β=0.86 single-cell cavity after 200 µm uniform removal. The cavity quenched at 27 MV/m without any heat treatment. The surface resistance achieved was less than 5nΩ at 1.8K. Substantial performance improvement is expected after heat treatment of the cavity and additional 20 µm VEP sequence. A cathode for 5-Cell ESS cavity is concomitantly under design stage.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-TUPCAV001

About •

Received ※ 21 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 23 August 2021 — Issue date ※ 17 March 2022

Cite •

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

FROFDV01

Systematic Investigation of Mid-T Furnace Baking for High-Q Performance

881

H. Ito, A. Araki, K. Umemori
KEK, Ibaraki, Japan
K. Takahashi
Sokendai, Ibaraki, Japan

We report on an investigation of the effect of a new baking process called "furnace baking" on the quality factor. Furnace baking is performed as the final step of the cavity surface treatment; the cavities are heated in a vacuum furnace in a temperature range of 200-800C for 3 h, followed by high-pressure rinsing and radio-frequency measurement. We find the anti-Q-slope for cavities furnace-baked at a temperature range of 250 to 400C and a reduction in the residual resistance for all cavities. In particular, an extremely high Q value of 5·10¹⁰ at 16 MV/m and 2.0 K is obtained for cavities furnace-baked at 300C.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-FROFDV01

About •

Received ※ 21 June 2021 — Accepted ※ 24 February 2022 — Issue date ※ 30 April 2022

Cite •

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