LINAC2018 - List of Authors (Hayano, H.)

Paper	Title	Page
TUPO030	Precise Evaluation of Characteristic of the Multi-layer Thin-film Superconductor Consisting of NbN and Insulator on Pure Nb Substrate	391
TUOP03	use link to see paper's listing under its alternate paper code
	R. Katayama, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of the cavity with a multilayer thin-film structure that consists of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrating into the superconductor layer, and it is predicted to depend on the combination of the film thickness. We made samples that have NbN/SiO2 thin-film structure on pure Nb substrate with several thicknesses of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of the NbN sample with a thickness of 200 nm by using the third-harmonic voltage method. In addition, we report the preliminary results to evaluate the dependence of the effective Hc1 on the thickness of the NbN film in the range 50 nm-200 nm.
	Slides TUPO030 [0.305 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO030
About •	paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO050	Construction of Thin-film Coating System Toward the Realization of Superconducting Multilayered Structure	445
	R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan Y. Iwashita, R. Katayama Kyoto ICR, Uji, Kyoto, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Although S-I-S (superconductor-insulator-superconductor) multilayered structure is expected to increase the maximum acceleration gradient of SRF cavities, in order for it to function in reality, it is necessary to develop a coating processing that can realize high purity and quality superconducting thin-films. We launched the co-sputtering system to create superconducting alloy thin-films such as Nb3Sn and to research how the characteristics of them change depending on the coating conditions. The deposition rate of two elements was optimized by adjusting each input power, so we successfully obtained an alloy thin-film having appropriate composition ratio. In addition, we developed another experimental equipment for coating on the inner surface of the 3GHz TESLA type small cavities. A cylindrical shape Nb in which some permanent magnets are inserted was adopted as the sputtering target. Glow discharge of the target was confirmed, and the inner-sputtering test was conducted. This presentation reports the specifications of the two sputtering apparatuses and the results of the coating test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO050
About •	paper received ※ 18 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO053	Fabrication of Nb Mushroom Shaped Cavity for Evaluation of Multi-layer Thin-film Superconductor	454
	H. Oikawa Utsunomiya University, Utsunomiya, Japan K. Enami, H. Hayano, H. Inoue KEK, Ibaraki, Japan T. Higashiguchi Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
	The accelerating gradient of the Nb superconducting RF cavity seems to reach the limit due to the RF critical magnetic field of the Nb material. To obtain more higher gradient, there has been proposed a method of increasing an RF critical magnetic field of the cavity inner surface by coating of multi-layer thin-film superconductor. It is needed to demonstrate improvement RF critical magnetic field of the RF cavity coated with multi-layer thin-film superconductor. To optimize thin-film superconductor, sample tests are required. A cavity for sample test is necessary to produce a strong RF magnetic field parallel to the surface of the sample for evaluating RF critical magnetic field. For such a cavity, we designed a mushroom shaped cavity made of Nb which is operated in cryogenic temperature. Input and pick up antenna coupler are also designed electrically and mechanically. The connection design of sample plate and cavity bottom plate in superconducting state is also designed. The Nb mushroom shaped cavity is under fabrication. Fabrication method and status are reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO053
About •	paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO066	Lower Critical Field Measurement of Thin Film Superconductor	484
	H. Ito Sokendai, Ibaraki, Japan C.Z. Antoine CEA/IRFU, Gif-sur-Yvette, France A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan R. Ito, T. Nagata ULVAC, Inc, Chiba, Japan Y. Iwashita, R. Katayama, H. Tongu Kyoto ICR, Uji, Kyoto, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839. Superconducting thin film is the promising technology to increase the performance of SRF cavities. The lower critical field Hc1, which is one of the important physical parameters characterizing a superconducting material, will be enhanced by coating Nb with thin film superconductor such as NbN. To investigate the Hc1, we developed the Hc1 measurement system using the third harmonic response of applied AC magnetic field. The measurement system consists of helium cryostat with two of GM refrigerators, sample Cu stage, solenoid coil Cu mount, solenoid coil, temperature sensors, and liquid helium level meter. AC magnetic field is produced by a coil which is driven by function generator and power amplifier at around 1 kHz. In order to control the temperature of the sample, we installed heaters and thermal anchors which could be moved by the motor. By this temperature control the sample state can be easily transferred from Meissner state to mixed state. So that the measurement is repeated for various applied magnetic field, and the transition curve can be made. In this report, measurement result of the bulk Nb sample and NbN-SiO2 multilayer thin film sample will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO066
About •	paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO067	Study on New Removal Thickness Distribution Improvement Methods for Niobium 9-cell Cavity Vertical Electropolishing with Ninja Cathode	488
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	Marui Galvanizing Co., Ltd. has been developing niobium 9-cell cavity vertical electropolishing (VEP) technologies with Ninja cathode in collaboration with KEK. Conventional 9-cell cavity VEP had a serious problem, which was asymmetry of removal thickness distribution. Usually removal thickness of upper side became larger than lower side in case of both in-cell and inter-cell. So far, as one solution, we proposed bubble diffusion prevention method and proved it was effective for uniform removal. This time, as other new solution, we tried cavity flip upside down and Ninja cathode masking VEP methods. In this article we will report the purpose, intention and VEP experiment result of these methods.
	Poster TUPO067 [0.858 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO067
About •	paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO068	Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance	491
	V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan H. Oikawa Utsunomiya University, Utsunomiya, Japan
	Vertical electropolishing (VEP) technique have been successfully developed for 1.3 GHz niobium (Nb) single cell cavity to achieve a smooth surface with uniform removal and better RF performance as achieved after horizontal EP (HEP) process. VEP parameters for 1.3 GHz Nb nine-cell cavities are being studied using a nine-cell coupon cavity and our unique Ninja cathode. The investigated VEP parameters heretofore were applied on a 1.3 GHz Tesla shape nine-cell superconducting RF cavity for bulk removal of 100 µm followed by fine removal of 20 and 10 µm. The interior surface was found to be smooth and shiny after the VEP process. Our recently developed dual flow technique, in which the EP acid is flown separately in the Ninja cathode housing and cavity, yielded lower asymmetry in removal along the cavity length. The cavity was tested in a vertical cryostat after the final VEP process. The cavity achieved 28.3 MV/m at Q0 value of 6.7x109. The cavity performance was almost the same as in the baseline vertical test performed after the HEP process.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO068
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO069	Development of Vertical Electropolishing Facility for Nb 9-cell Cavity (2)	494
	Y.I. Ida, V. Chouhan, K.N. Nii MGH, Hyogo-ken, Japan T. Akabori, G.M. Mitoya, K. Miyano HKK, Morioka, Japan Y. Anetai, F. Takahashi WING. Co.Ltd, Iwate-ken, Japan H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	In IPAC18 (Vancouver, Canada), we reported our first step of development of niobium 9-cell cavity vertical electropolishing (VEP) facility. In this article, we will report the method, system for uniform polishing for niobium 9-cell cavities and the current situation of our 9-cell cavity VEP facility (The result of polishing uniformity, vertical test will be presented in other posters of this conference). In addition, we will show the movie of experiments of VEP-3 with Ninja cathode. This facility aims not only for test VEP but also for mass production and long-time operation.
	Poster TUPO069 [0.316 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO069
About •	paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO076	An Innovative Nb3Sn Film Approach and Its Potential for SRF Applications	513
	E.Z. Barzi, D. Turrioni, C. Ciaccia Fermilab, Batavia, Illinois, USA G.V. Eremeev, R.L. Geng, R.A. Rimmer, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA S. Falletta Politecnico di Torino, Torino, Italy H. Hayano, T. Saeki KEK, Ibaraki, Japan H. Ito Sokendai, Ibaraki, Japan A. Kikuchi NIMS, Tsukuba, Ibaraki, Japan
	Funding: Work supported by U.S. DOE contract No. DE-AC02-07CH11359 A novel electro-chemical technique to produce Nb3Sn films on Nb substrates was developed and optimized at Fermilab. The Nb3Sn phase is obtained in a two-electrode cell, by electrodeposition from aqueous solutions of Sn layers and Cu intermediate layers onto Nb substrates. Subsequent thermal treatments in inert atmosphere are realized at a maximum temperature of 700°C to obtain the Nb3Sn superconducting phase. Several superconduct-ing Nb3Sn films were obtained on Nb substrates by study-ing and optimizing most parameters of the electro-plating process. Samples were characterized at Fermilab, NIMS, KEK and JLAB, including EPMA analyses, DC and in-ductive tests of critical temperature Tc0, and lower critical field Hc1(4.2 K) by SQUID. In parallel to sample devel-opment and fabrication at FNAL, at JLAB and KEK effort was put into etching and electro-polishing techniques adequate to remove the Cu and bronze phases from the samples’ outer surface. This is necessary prior to meas-urements at JLAB of the surface impedance of flat sam-ples in a setup that make use of an RF host cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO076
About •	paper received ※ 21 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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THPO005	High Aspect Ratio Beam Generation with the Phase-space Rotation Technique for Linear Colliders	685
	M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan P. Piot Northern Illinois University, DeKalb, Illinois, USA J.G. Power ANL, Argonne, Illinois, USA K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Funding: This work is partly supported by Grant-in-Aid for Scientific Research (B) and US-Japan Science and Technology Cooperation Program in High Energy Physics. Linear colliders is the only way to realize e⁺ e⁻ collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO005
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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Paper

Title

Page

Precise Evaluation of Characteristic of the Multi-layer Thin-film Superconductor Consisting of NbN and Insulator on Pure Nb Substrate

391

TUOP03

use link to see paper's listing under its alternate paper code

R. Katayama, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of the cavity with a multilayer thin-film structure that consists of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrating into the superconductor layer, and it is predicted to depend on the combination of the film thickness. We made samples that have NbN/SiO2 thin-film structure on pure Nb substrate with several thicknesses of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of the NbN sample with a thickness of 200 nm by using the third-harmonic voltage method. In addition, we report the preliminary results to evaluate the dependence of the effective Hc1 on the thickness of the NbN film in the range 50 nm-200 nm.

Slides TUPO030 [0.305 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO030

About •

paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO050

Construction of Thin-film Coating System Toward the Realization of Superconducting Multilayered Structure

445

R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
Y. Iwashita, R. Katayama
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Although S-I-S (superconductor-insulator-superconductor) multilayered structure is expected to increase the maximum acceleration gradient of SRF cavities, in order for it to function in reality, it is necessary to develop a coating processing that can realize high purity and quality superconducting thin-films. We launched the co-sputtering system to create superconducting alloy thin-films such as Nb3Sn and to research how the characteristics of them change depending on the coating conditions. The deposition rate of two elements was optimized by adjusting each input power, so we successfully obtained an alloy thin-film having appropriate composition ratio. In addition, we developed another experimental equipment for coating on the inner surface of the 3GHz TESLA type small cavities. A cylindrical shape Nb in which some permanent magnets are inserted was adopted as the sputtering target. Glow discharge of the target was confirmed, and the inner-sputtering test was conducted. This presentation reports the specifications of the two sputtering apparatuses and the results of the coating test.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO050

About •

paper received ※ 18 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO053

Fabrication of Nb Mushroom Shaped Cavity for Evaluation of Multi-layer Thin-film Superconductor

454

H. Oikawa
Utsunomiya University, Utsunomiya, Japan
K. Enami, H. Hayano, H. Inoue
KEK, Ibaraki, Japan
T. Higashiguchi
Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan

The accelerating gradient of the Nb superconducting RF cavity seems to reach the limit due to the RF critical magnetic field of the Nb material. To obtain more higher gradient, there has been proposed a method of increasing an RF critical magnetic field of the cavity inner surface by coating of multi-layer thin-film superconductor. It is needed to demonstrate improvement RF critical magnetic field of the RF cavity coated with multi-layer thin-film superconductor. To optimize thin-film superconductor, sample tests are required. A cavity for sample test is necessary to produce a strong RF magnetic field parallel to the surface of the sample for evaluating RF critical magnetic field. For such a cavity, we designed a mushroom shaped cavity made of Nb which is operated in cryogenic temperature. Input and pick up antenna coupler are also designed electrically and mechanically. The connection design of sample plate and cavity bottom plate in superconducting state is also designed. The Nb mushroom shaped cavity is under fabrication. Fabrication method and status are reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO053

About •

paper received ※ 17 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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

TUPO066

Lower Critical Field Measurement of Thin Film Superconductor

484

H. Ito
Sokendai, Ibaraki, Japan
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
Y. Iwashita, R. Katayama, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839.
Superconducting thin film is the promising technology to increase the performance of SRF cavities. The lower critical field Hc1, which is one of the important physical parameters characterizing a superconducting material, will be enhanced by coating Nb with thin film superconductor such as NbN. To investigate the Hc1, we developed the Hc1 measurement system using the third harmonic response of applied AC magnetic field. The measurement system consists of helium cryostat with two of GM refrigerators, sample Cu stage, solenoid coil Cu mount, solenoid coil, temperature sensors, and liquid helium level meter. AC magnetic field is produced by a coil which is driven by function generator and power amplifier at around 1 kHz. In order to control the temperature of the sample, we installed heaters and thermal anchors which could be moved by the motor. By this temperature control the sample state can be easily transferred from Meissner state to mixed state. So that the measurement is repeated for various applied magnetic field, and the transition curve can be made. In this report, measurement result of the bulk Nb sample and NbN-SiO2 multilayer thin film sample will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO066

About •

paper received ※ 19 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

Export •

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

TUPO067

Study on New Removal Thickness Distribution Improvement Methods for Niobium 9-cell Cavity Vertical Electropolishing with Ninja Cathode

488

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Marui Galvanizing Co., Ltd. has been developing niobium 9-cell cavity vertical electropolishing (VEP) technologies with Ninja cathode in collaboration with KEK. Conventional 9-cell cavity VEP had a serious problem, which was asymmetry of removal thickness distribution. Usually removal thickness of upper side became larger than lower side in case of both in-cell and inter-cell. So far, as one solution, we proposed bubble diffusion prevention method and proved it was effective for uniform removal. This time, as other new solution, we tried cavity flip upside down and Ninja cathode masking VEP methods. In this article we will report the purpose, intention and VEP experiment result of these methods.

Poster TUPO067 [0.858 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO067

About •

paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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

TUPO068

Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance

491

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Vertical electropolishing (VEP) technique have been successfully developed for 1.3 GHz niobium (Nb) single cell cavity to achieve a smooth surface with uniform removal and better RF performance as achieved after horizontal EP (HEP) process. VEP parameters for 1.3 GHz Nb nine-cell cavities are being studied using a nine-cell coupon cavity and our unique Ninja cathode. The investigated VEP parameters heretofore were applied on a 1.3 GHz Tesla shape nine-cell superconducting RF cavity for bulk removal of 100 µm followed by fine removal of 20 and 10 µm. The interior surface was found to be smooth and shiny after the VEP process. Our recently developed dual flow technique, in which the EP acid is flown separately in the Ninja cathode housing and cavity, yielded lower asymmetry in removal along the cavity length. The cavity was tested in a vertical cryostat after the final VEP process. The cavity achieved 28.3 MV/m at Q0 value of 6.7x109. The cavity performance was almost the same as in the baseline vertical test performed after the HEP process.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO068

About •

paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO069

Development of Vertical Electropolishing Facility for Nb 9-cell Cavity (2)

494

Y.I. Ida, V. Chouhan, K.N. Nii
MGH, Hyogo-ken, Japan
T. Akabori, G.M. Mitoya, K. Miyano
HKK, Morioka, Japan
Y. Anetai, F. Takahashi
WING. Co.Ltd, Iwate-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

In IPAC18 (Vancouver, Canada), we reported our first step of development of niobium 9-cell cavity vertical electropolishing (VEP) facility. In this article, we will report the method, system for uniform polishing for niobium 9-cell cavities and the current situation of our 9-cell cavity VEP facility (The result of polishing uniformity, vertical test will be presented in other posters of this conference). In addition, we will show the movie of experiments of VEP-3 with Ninja cathode. This facility aims not only for test VEP but also for mass production and long-time operation.

Poster TUPO069 [0.316 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO069

About •

paper received ※ 13 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO076

An Innovative Nb3Sn Film Approach and Its Potential for SRF Applications

513

E.Z. Barzi, D. Turrioni, C. Ciaccia
Fermilab, Batavia, Illinois, USA
G.V. Eremeev, R.L. Geng, R.A. Rimmer, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
S. Falletta
Politecnico di Torino, Torino, Italy
H. Hayano, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
A. Kikuchi
NIMS, Tsukuba, Ibaraki, Japan

Funding: Work supported by U.S. DOE contract No. DE-AC02-07CH11359
A novel electro-chemical technique to produce Nb3Sn films on Nb substrates was developed and optimized at Fermilab. The Nb3Sn phase is obtained in a two-electrode cell, by electrodeposition from aqueous solutions of Sn layers and Cu intermediate layers onto Nb substrates. Subsequent thermal treatments in inert atmosphere are realized at a maximum temperature of 700°C to obtain the Nb3Sn superconducting phase. Several superconduct-ing Nb3Sn films were obtained on Nb substrates by study-ing and optimizing most parameters of the electro-plating process. Samples were characterized at Fermilab, NIMS, KEK and JLAB, including EPMA analyses, DC and in-ductive tests of critical temperature Tc0, and lower critical field Hc1(4.2 K) by SQUID. In parallel to sample devel-opment and fabrication at FNAL, at JLAB and KEK effort was put into etching and electro-polishing techniques adequate to remove the Cu and bronze phases from the samples’ outer surface. This is necessary prior to meas-urements at JLAB of the surface impedance of flat sam-ples in a setup that make use of an RF host cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO076

About •

paper received ※ 21 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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

THPO005

High Aspect Ratio Beam Generation with the Phase-space Rotation Technique for Linear Colliders

685

M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.G. Power
ANL, Argonne, Illinois, USA
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan
H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Funding: This work is partly supported by Grant-in-Aid for Scientific Research (B) and US-Japan Science and Technology Cooperation Program in High Energy Physics.
Linear colliders is the only way to realize e⁺ e⁻ collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO005

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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