SRF2017 - List of Authors (Tamashevich, Y.)

Paper	Title	Page
TUPB082	Setup of a Spatially Resolving Vector Magnetometry System for the Investigation of Flux Trapping in Superconducting Cavities	580
	B. Schmitz, K. Alomari, J. Knobloch, O. Kugeler, J.M. Köszegi, Y. Tamashevich HZB, Berlin, Germany
	Flux trapping is the major contribution to the residual resistance of superconducting cavities. In order to gain a better understanding of the mechanisms involved and aiming at an eventual minimization of trapped flux, a measurement setup based on AMR sensors was devised that allows for monitoring the magnetic field vector at various positions near the cavity surface. First results of the efforts are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB082
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB111	R&D Activities on Centrifugal Barrel Polishing of 1.3 GHz Niobium Cavities at DESY/University of Hamburg	655
	A.L. Prudnikava, B. Foster, Y. Tamashevich University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany A. Ermakov, B. Foster DESY, Hamburg, Germany Y. Tamashevich HZB, Berlin, Germany
	In this paper the status of research activities at ILC-HiGrade Lab (DESY/University of Hamburg) on Centrifugal Barrel Polishing (CBP) of 1.3 GHz Niobium Cavities is presented. We focus on CBP based on the polishing recipe reported by Fermi National Laboratory and Jefferson Lab. The aim is to gain a better understanding of the limitations of this technique, detailed characterization of the treated surface after each polishing step using a "coupon" single cell cavity. Plastic deformations upon initial CBP steps, embedded polishing media and residual damage upon final polishing were investigated at different areas of the cavity. C. A. Cooper, L. D. Cooley, Supercond. Sci. Technol. 26 (2013) 015011
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB111
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB113	Surface Characterization of Nitrided Niobium Surfaces	663
	A.L. Prudnikava, B. Foster University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany B. Foster DESY, Hamburg, Germany Y. Tamashevich HZB, Berlin, Germany Y. Tamashevich University of Hamburg, Hamburg, Germany
	Thermal treatment of niobium radio frequency cavities in nitrogen atmosphere is employed in ILCLS-II Project in order to improve the quality factor of Nb cavities. A so called "N-infusion" thermal treatment is applied without any post processing, , whereas "N-doping" requires the removal of the upper layer of 5-30 um. For better understanding the mechanism of such an improvement, a detailed characterization of the nitrided surface is necessary. Our studies are focused on characterization of the niobium surface subjected to such treatments (surface morphology, nitrogen concentration profile, hardness, phase composition). The sample preparation technique for studying the hydride precipitation in N-Nb system is presented, and current activities on studying of N-infused Nb samples by SQUID and PPMS are briefly discussed. A. Grassellino, et al, Supercond. Sci. Technol. 26 (2013) 102001. ** A. Grassellino, arXiv:1701.06077
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB113
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXA06	Advanced OST System for the Second-sound Test of Fully Dressed Cavities	703
	Y. Tamashevich HZB, Berlin, Germany Y. Tamashevich University of Hamburg, Hamburg, Germany
	Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.
	Slides THXA06 [9.681 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Setup of a Spatially Resolving Vector Magnetometry System for the Investigation of Flux Trapping in Superconducting Cavities

580

B. Schmitz, K. Alomari, J. Knobloch, O. Kugeler, J.M. Köszegi, Y. Tamashevich
HZB, Berlin, Germany

Flux trapping is the major contribution to the residual resistance of superconducting cavities. In order to gain a better understanding of the mechanisms involved and aiming at an eventual minimization of trapped flux, a measurement setup based on AMR sensors was devised that allows for monitoring the magnetic field vector at various positions near the cavity surface. First results of the efforts are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB082

Export •

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

TUPB111

R&D Activities on Centrifugal Barrel Polishing of 1.3 GHz Niobium Cavities at DESY/University of Hamburg

655

A.L. Prudnikava, B. Foster, Y. Tamashevich
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
A. Ermakov, B. Foster
DESY, Hamburg, Germany
Y. Tamashevich
HZB, Berlin, Germany

In this paper the status of research activities at ILC-HiGrade Lab (DESY/University of Hamburg) on Centrifugal Barrel Polishing (CBP) of 1.3 GHz Niobium Cavities is presented. We focus on CBP based on the polishing recipe reported by Fermi National Laboratory and Jefferson Lab*. The aim is to gain a better understanding of the limitations of this technique, detailed characterization of the treated surface after each polishing step using a "coupon" single cell cavity. Plastic deformations upon initial CBP steps, embedded polishing media and residual damage upon final polishing were investigated at different areas of the cavity.
* C. A. Cooper, L. D. Cooley, Supercond. Sci. Technol. 26 (2013) 015011

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB111

Export •

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

TUPB113

Surface Characterization of Nitrided Niobium Surfaces

663

A.L. Prudnikava, B. Foster
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
B. Foster
DESY, Hamburg, Germany
Y. Tamashevich
HZB, Berlin, Germany
Y. Tamashevich
University of Hamburg, Hamburg, Germany

Thermal treatment of niobium radio frequency cavities in nitrogen atmosphere is employed in ILCLS-II Project in order to improve the quality factor of Nb cavities. A so called "N-infusion" thermal treatment is applied without any post processing*, **, whereas "N-doping" requires the removal of the upper layer of 5-30 um. For better understanding the mechanism of such an improvement, a detailed characterization of the nitrided surface is necessary. Our studies are focused on characterization of the niobium surface subjected to such treatments (surface morphology, nitrogen concentration profile, hardness, phase composition). The sample preparation technique for studying the hydride precipitation in N-Nb system is presented, and current activities on studying of N-infused Nb samples by SQUID and PPMS are briefly discussed.
* A. Grassellino, et al, Supercond. Sci. Technol. 26 (2013) 102001.
** A. Grassellino, arXiv:1701.06077

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB113

Export •

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

THXA06

Advanced OST System for the Second-sound Test of Fully Dressed Cavities

703

Y. Tamashevich
HZB, Berlin, Germany
Y. Tamashevich
University of Hamburg, Hamburg, Germany

Cavities which exhibit a low field quench are normally discarded from usage in accelerator projects. However, they can be repaired if the exact location of the quench is known. Optical inspection alone cannot reliably locate the source of a quench. Methods that directly measure the quench, such as thermometry or second sound detection, could so far only be performed at undressed cavities. A new, specially designed, second-sound system for the first time allows the localization of the quench in multicell cavities equipped with a helium vessel. It can be easily installed in the helium pipe of the cavity. Information on the quench location can be acquired during a standard rf test. A new algorithm localizes the quench based on the real path of the second-sound wave around the cavity surface, rather than using simple triangulation. The implemented pathfinding method leads to a high precision and high accuracy of the quench location. This was verified by testing standard dressed 9-cell XFEL cavities. The system can be easily applied to other cavity shapes and sizes.

Slides THXA06 [9.681 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THXA06

Export •

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