SRF2017 - List of Authors (Kato, S.)

Paper	Title	Page
TUYBA01	Progress on Characterization and Optimization of Multilayers	368
	C.Z. Antoine CEA/DSM/IRFU, France M. Aburas, A. Four CEA/DRF/IRFU, Gif-sur-Yvette, France H. Hayano, S. Kato, T. Kubo, T. Saeki KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan
	Multilayers MgO/NbN/MgO/Nb with several thicknesses are being tested by local magnetometry, Scanning tunneling and various standard structural techniques experiment providing usefull information to compare experiments and recent theoretical advances proposed by A. Gurevich or T. Kubo.
	Slides TUYBA01 [5.819 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUYBA01
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TUPB073	Vertical Electro-polishing Collaboration Between Cornell, KEK, and Marui Galvanizing Co. Ltd	563
	F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi MGH, Hyogo-ken, Japan H. Hayano, S. Kato, T. Saeki KEK, Ibaraki, Japan
	Cornell's SRF group, KEK, and Marui Galvanizing Co. Ltd (MGI) have collaborated since 2014 on Vertical Electro-Polishing (VEP) R&D as a part of a US/Japan Program for Cooperation in High Energy Physics. We have focused on an improvement of removal uniformity during the VEP process. MGI and KEK have developed their original VEP cathode named i-cathode Ninja®, which has four retractable wing-shape parts per cell. Cornell processed one single cell cavity with VEP using this cathode and performed a vertical test. KEK also provided one 9-cell cavity to Cornell. Cornell then performed surface treatments including Cornell VEP and RF test on this 9-cell cavity. The progress by the VEP collaboration and RF test results are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB073
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TUPB091	Study on Vertical Electropolising of 9-cell Niobium Coupon Cavity	602
	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
	Authors report a study on vertical electropolishing (VEP) carried out for a 1.3 GHz 9-cell niobium (Nb) coupon cavity using a unique cathode namely 'Ninja Cathode'. The design of the cathode for VEP of a 9-cell cavity was based on the Ninja cathode used for 1-cell cavity since the 1-cell Ninja cathode was found effective to reduce longitudinal asymmetry in material removal and to obtain a smooth surface of a 1-cell cavity. Moreover, 1-cell Nb cavities after being treated in VEP using the Ninja cathode showed good performance in vertical RF tests. The 9-cell coupon cavity used in this study was designed to have totally nine coupons set on the iris and equator positions of the first, fifth and ninth cells. These three cells contain viewports as well at their upper and lower iris positions. Measurement of currents from the individual coupons and in-situ observation are possible using the cavity to understand EP phenomenon at different locations of the cavity. VEP results, which include removal thicknesses at different positions of the cavity and surface study of the coupons, are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB091
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TUPB092	Analysis of Niobium Surface and Generated Particles in Vertical Electropolishing of Single-cell Coupon Cavity	607
	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
	In our previous studies, we have reported parameter investigation for vertical electropolishing (VEP) of 1-cell niobium (Nb) tesla/ILC type cavities using a Ninja cathode. A 1-cell coupon cavity containing six Nb disk coupons at its different positions was found effective to reduce time and cost to establish an optimized VEP recipe. In this work, we present surface analyses of VEPed Nb coupon surfaces using scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS). Surfaces contained micro- and nano-sized particles which were found with random distributions and different number densities on the beam pipe and iris coupons. Surfaces of equator coupons were found to have relatively less number of particles or almost clean. To analyze particles, a few particles were picked-up from a coupon surface using a tungsten tip under SEM and analyzed with EDX while the coupon was moved out from the SEM chamber to avoid its effect in EDX spectra. The particles were confirmed as oxygen-rich niobium and contained fluorine and carbon also. XPS analysis of the coupon surfaces was also carried out for further study of surface chemistry.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB092
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TUPB093	Nb Single-cell Cavity Vertical Electro-polishing with Ninja Cathode and Evaluation of its Accelerating Gradient	612
	K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi MGH, Hyogo-ken, Japan P. Carbonnier, Y. Gasser, L. Maurice CEA/IRFU, Gif-sur-Yvette, France F. Éozénou, C. Servouin CEA/DSM/IRFU, France H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe KEK, Ibaraki, Japan Th. Proslier CEA/DRF/IRFU, Gif-sur-Yvette, France
	Marui Galvanizing Co. Ltd. has been improving Vertical Electro-Polishing (VEP) technology for Nb superconducting RF cavity in collaboration with KEK. In this collaboration, we developed a unique cathode namely Ninja cathode for VEP treatment of Nb cavities. We have already reported that longitudinal symmetry in niobium removal and surface state of a single cell cavity were improved after VEP using the Ninja cathode. In this article, we report a result of accelerating gradient evaluation for 1.3 GHz single cell RF cavity after VEP with Ninja cathode in collaboration with KEK and CEA Saclay.
	Poster TUPB093 [0.704 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB093
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THPB055	Plasma-enhanced ALD System for SRF Cavity	870
	S. Kato, H. Hayano KEK, Ibaraki, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program by MEXT and partly by JST-CREST. A remote PEALD (Plasma-enhanced Atomic Layer Deposition) system which would offer a high conformality and a low deposition temperature has been being developed for deposition of NbN on an SRF cavity. The deposition equipment consists of a deposition chamber, a remote plasma exciter, a precursor supply system, vacuum pumps, a quartz crystal microbalance (QCM) as a film growth rate meter, a detoxifying system and a safety system. An RF frequency of 13.56MHz was used for the inductively coupled plasma exciter of a reactant gas. The whole equipment is in a draft booth for operation safety. For ALD of an SRF cavity, the ALD system allows us to easily replace the deposition chamber with a single cell Nb cavity. The prepared precursors are tris[ethylmethylamido][tert-butylimido] niobium (TBTEMN) and trimethylaluminium (TMA). Ammonia, hydrogen and water are also prepared as reactants. We will report the ALD system design and result of the NbN deposition on sample coupons which are analysed with SEM, EDX and XPS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB055
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Progress on Characterization and Optimization of Multilayers

368

C.Z. Antoine
CEA/DSM/IRFU, France
M. Aburas, A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, S. Kato, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan

Multilayers MgO/NbN/MgO/Nb with several thicknesses are being tested by local magnetometry, Scanning tunneling and various standard structural techniques experiment providing usefull information to compare experiments and recent theoretical advances proposed by A. Gurevich or T. Kubo.

Slides TUYBA01 [5.819 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUYBA01

Export •

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

TUPB073

Vertical Electro-polishing Collaboration Between Cornell, KEK, and Marui Galvanizing Co. Ltd

563

F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, T. Saeki
KEK, Ibaraki, Japan

Cornell's SRF group, KEK, and Marui Galvanizing Co. Ltd (MGI) have collaborated since 2014 on Vertical Electro-Polishing (VEP) R&D as a part of a US/Japan Program for Cooperation in High Energy Physics. We have focused on an improvement of removal uniformity during the VEP process. MGI and KEK have developed their original VEP cathode named i-cathode Ninja®, which has four retractable wing-shape parts per cell. Cornell processed one single cell cavity with VEP using this cathode and performed a vertical test. KEK also provided one 9-cell cavity to Cornell. Cornell then performed surface treatments including Cornell VEP and RF test on this 9-cell cavity. The progress by the VEP collaboration and RF test results are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB073

Export •

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

TUPB091

Study on Vertical Electropolising of 9-cell Niobium Coupon Cavity

602

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

Authors report a study on vertical electropolishing (VEP) carried out for a 1.3 GHz 9-cell niobium (Nb) coupon cavity using a unique cathode namely 'Ninja Cathode'. The design of the cathode for VEP of a 9-cell cavity was based on the Ninja cathode used for 1-cell cavity since the 1-cell Ninja cathode was found effective to reduce longitudinal asymmetry in material removal and to obtain a smooth surface of a 1-cell cavity. Moreover, 1-cell Nb cavities after being treated in VEP using the Ninja cathode showed good performance in vertical RF tests. The 9-cell coupon cavity used in this study was designed to have totally nine coupons set on the iris and equator positions of the first, fifth and ninth cells. These three cells contain viewports as well at their upper and lower iris positions. Measurement of currents from the individual coupons and in-situ observation are possible using the cavity to understand EP phenomenon at different locations of the cavity. VEP results, which include removal thicknesses at different positions of the cavity and surface study of the coupons, are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB091

Export •

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

TUPB092

Analysis of Niobium Surface and Generated Particles in Vertical Electropolishing of Single-cell Coupon Cavity

607

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

In our previous studies, we have reported parameter investigation for vertical electropolishing (VEP) of 1-cell niobium (Nb) tesla/ILC type cavities using a Ninja cathode. A 1-cell coupon cavity containing six Nb disk coupons at its different positions was found effective to reduce time and cost to establish an optimized VEP recipe. In this work, we present surface analyses of VEPed Nb coupon surfaces using scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray photoelectron spectroscopy (XPS). Surfaces contained micro- and nano-sized particles which were found with random distributions and different number densities on the beam pipe and iris coupons. Surfaces of equator coupons were found to have relatively less number of particles or almost clean. To analyze particles, a few particles were picked-up from a coupon surface using a tungsten tip under SEM and analyzed with EDX while the coupon was moved out from the SEM chamber to avoid its effect in EDX spectra. The particles were confirmed as oxygen-rich niobium and contained fluorine and carbon also. XPS analysis of the coupon surfaces was also carried out for further study of surface chemistry.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB092

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

TUPB093

Nb Single-cell Cavity Vertical Electro-polishing with Ninja Cathode and Evaluation of its Accelerating Gradient

612

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
P. Carbonnier, Y. Gasser, L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
F. Éozénou, C. Servouin
CEA/DSM/IRFU, France
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
Th. Proslier
CEA/DRF/IRFU, Gif-sur-Yvette, France

Marui Galvanizing Co. Ltd. has been improving Vertical Electro-Polishing (VEP) technology for Nb superconducting RF cavity in collaboration with KEK. In this collaboration, we developed a unique cathode namely Ninja cathode for VEP treatment of Nb cavities. We have already reported that longitudinal symmetry in niobium removal and surface state of a single cell cavity were improved after VEP using the Ninja cathode. In this article, we report a result of accelerating gradient evaluation for 1.3 GHz single cell RF cavity after VEP with Ninja cathode in collaboration with KEK and CEA Saclay.

Poster TUPB093 [0.704 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB093

Export •

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

THPB055

Plasma-enhanced ALD System for SRF Cavity

870

S. Kato, H. Hayano
KEK, Ibaraki, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program by MEXT and partly by JST-CREST.
A remote PEALD (Plasma-enhanced Atomic Layer Deposition) system which would offer a high conformality and a low deposition temperature has been being developed for deposition of NbN on an SRF cavity. The deposition equipment consists of a deposition chamber, a remote plasma exciter, a precursor supply system, vacuum pumps, a quartz crystal microbalance (QCM) as a film growth rate meter, a detoxifying system and a safety system. An RF frequency of 13.56MHz was used for the inductively coupled plasma exciter of a reactant gas. The whole equipment is in a draft booth for operation safety. For ALD of an SRF cavity, the ALD system allows us to easily replace the deposition chamber with a single cell Nb cavity. The prepared precursors are tris[ethylmethylamido][tert-butylimido] niobium (TBTEMN) and trimethylaluminium (TMA). Ammonia, hydrogen and water are also prepared as reactants. We will report the ALD system design and result of the NbN deposition on sample coupons which are analysed with SEM, EDX and XPS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB055

Export •

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