LINAC2014 - List of Authors (Kubo, T.)

Paper

Title

Page

Vortex-Penetration Field at a Groove with a Depth Smaller than the Penetration Depth

590

T. Kubo
KEK, Ibaraki, Japan

Analytical models of the magnetic field enhancement at pits were presented at SRF2013 last year. In this presentation, I will show updated models.
proceedings of SRF 2013, Paris, France (2013), p. 430

TUPP074

Study on Fabrication of Superconducting RF 9-cell Cavity for ILC at KEK.

T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara
SPS, Funabashi-shi, Japan
F. Yasuda
The University of Tokyo, Institute of Physics, Tokyo, Japan

We had constructed the Cavity Fabrication Facility (CFF) for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the study on the fabrication of 9-cell cavity for International Linear Collier (ILC) from 2009 using this facility. The study is focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We finished the fabrication of two 9-cell cavities by using tools, machines, and equipment of this facility. This article reports the current status of the studies on fabrication of cavity, including the results of vertical tests for the 9-cell cavities which were fabricated in this facillity.

THPP074

Superconducting Nano-Layer Coating Without Insulator

1026

T. Kubo
KEK, Ibaraki, Japan

Last year, we submitted a theoretical paper on a multilayered structure with a single superconductor layer and a single insulator layer formed on a bulk superconductor, where the magnetic field on the interface of the bulk superconductor were derived with a rigorous calculation of the magnetic field attenuation in the multilayered structure and the general formula for the vortex penetration field of the superconductor layer were computed in terms of the force acting on a vortex. Using the formulae, a combination of the thicknesses of superconductor and insulator layers that can realize the enhanced field limit can be found for any given materials. Then our results on optimum combinations of layer thicknesses and resultant field limits were reproduced by other group, where they carried out the same computation in terms of energy. To confirm these theoretical implications, experiments to measure vortex penetration fields of multilayered superconductors are planned. Theoretical studies to help the planned experiments are also in progress. In this presentation we will explain our ongoing experimental and theoretical studies.
T. Kubo, Y. Iwashita, T. Saeki, Applied Physics Letters 104, 032603 (2014);
proceedings of SRF 2013, Paris, France (2013), p. 427;
proceedings of IPAC13, Shanghai, China (2013), p. 2343.

THPP075

Development of Superconducting Spoke Cavity for Electron Accelerators

1030

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
E. Cenni, H. Fujisawa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, M. Sawamura
JAEA, Ibaraki-ken, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have launched a development program of a superconducting spoke cavity for electron acceleration, in order to realize a compact industrial-use X-ray source with the laser-Compton scattering. Efforts for optimizing a cavity design by the electromagnetic field simulation, tracking of multipactor electrons and mechanical property calculations have been continued so far. The optimization processes reached the final stage, and studies toward fabrication processes started. In this presentation, we will show results and processes of the optimization. Attempts to fabricate the spoke cavity, which have just begun, will also be presented.

THPP093

Combined System of Optical Inspection and Local Grinder

1065

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
H. Hayano, T. Kubo, K. Watanabe, Y. Yamamoto
KEK, Ibaraki, Japan

Optical inspections on superconducting accelerating tubes have been playing an important role on improving their accelerating gradients. Instead of treatments on whole cavity inner surfaces to eliminate the found defects on the surfaces, the local grinding method succeeds to remove them efficiently. A combined system of the optical inspection and the local Grinding machines are fabricated. The overview of the system will be presented.

Paper	Title	Page
TUPP071	Vortex-Penetration Field at a Groove with a Depth Smaller than the Penetration Depth	590
	T. Kubo KEK, Ibaraki, Japan
	Analytical models of the magnetic field enhancement at pits were presented at SRF2013 last year. In this presentation, I will show updated models. proceedings of SRF 2013, Paris, France (2013), p. 430

TUPP074	Study on Fabrication of Superconducting RF 9-cell Cavity for ILC at KEK.
	T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara SPS, Funabashi-shi, Japan F. Yasuda The University of Tokyo, Institute of Physics, Tokyo, Japan
	We had constructed the Cavity Fabrication Facility (CFF) for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the study on the fabrication of 9-cell cavity for International Linear Collier (ILC) from 2009 using this facility. The study is focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We finished the fabrication of two 9-cell cavities by using tools, machines, and equipment of this facility. This article reports the current status of the studies on fabrication of cavity, including the results of vertical tests for the 9-cell cavities which were fabricated in this facillity.

THPP074	Superconducting Nano-Layer Coating Without Insulator	1026
	T. Kubo KEK, Ibaraki, Japan
	Last year, we submitted a theoretical paper on a multilayered structure with a single superconductor layer and a single insulator layer formed on a bulk superconductor, where the magnetic field on the interface of the bulk superconductor were derived with a rigorous calculation of the magnetic field attenuation in the multilayered structure and the general formula for the vortex penetration field of the superconductor layer were computed in terms of the force acting on a vortex. Using the formulae, a combination of the thicknesses of superconductor and insulator layers that can realize the enhanced field limit can be found for any given materials. Then our results on optimum combinations of layer thicknesses and resultant field limits were reproduced by other group, where they carried out the same computation in terms of energy. To confirm these theoretical implications, experiments to measure vortex penetration fields of multilayered superconductors are planned. Theoretical studies to help the planned experiments are also in progress. In this presentation we will explain our ongoing experimental and theoretical studies. T. Kubo, Y. Iwashita, T. Saeki, Applied Physics Letters 104, 032603 (2014); proceedings of SRF 2013, Paris, France (2013), p. 427; proceedings of IPAC13, Shanghai, China (2013), p. 2343.

THPP075	Development of Superconducting Spoke Cavity for Electron Accelerators	1030
	T. Kubo, T. Saeki KEK, Ibaraki, Japan E. Cenni, H. Fujisawa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan R. Hajima, M. Sawamura JAEA, Ibaraki-ken, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have launched a development program of a superconducting spoke cavity for electron acceleration, in order to realize a compact industrial-use X-ray source with the laser-Compton scattering. Efforts for optimizing a cavity design by the electromagnetic field simulation, tracking of multipactor electrons and mechanical property calculations have been continued so far. The optimization processes reached the final stage, and studies toward fabrication processes started. In this presentation, we will show results and processes of the optimization. Attempts to fabricate the spoke cavity, which have just begun, will also be presented.

THPP093	Combined System of Optical Inspection and Local Grinder	1065
	Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan H. Hayano, T. Kubo, K. Watanabe, Y. Yamamoto KEK, Ibaraki, Japan
	Optical inspections on superconducting accelerating tubes have been playing an important role on improving their accelerating gradients. Instead of treatments on whole cavity inner surfaces to eliminate the found defects on the surfaces, the local grinding method succeeds to remove them efficiently. A combined system of the optical inspection and the local Grinding machines are fabricated. The overview of the system will be presented.