NAPAC2016 - List of Keywords (niobium)

Paper	Title	Other Keywords	Page
MOPOB68	A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films	ion, laser, controls, electron	221
	J. Musson, K. Macha, H.L. Phillips JLab, Newport News, Virginia, USA W. Cao, H. Elsayed-Ali ODU, Norfolk, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB68
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WEB1CO02	Investigation of Structural Development in the Two-Step Diffusion Coating of Nb3Sn on Niobium	ion, SRF, experiment, cavity	659
	U. Pudasaini, M.J. Kelley The College of William and Mary, Williamsburg, Virginia, USA G.V. Eremeev, M.J. Kelley, C.E. Reece JLab, Newport News, Virginia, USA M.J. Kelley, J. Tuggle Virginia Polytechnic Institute and State University, Blacksburg, USA
	Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475. The potential for higher operating temperatures and increased accelerating gradient has attracted SRF researchers to Nb3Sn coatings on niobium for nearly 50 years. The two-step tin vapor diffusion: nucleation followed by deposition appears to be a promising technique to prepare Nb3Sn coatings on interior cavity surface. We have undertaken a fundamental materials study of the nucleation and deposition steps. Nucleation was accomplished within parameter ranges: 300 - 500 °C, 1 - 5 hrs duration, 5 mg - 1 g SnCl2 and 1 g Sn. The resulting deposit consists of (< 10%) coverage of tin particles, as determined by SEM/EDS, while XPS and SAM discovered extra tin film between these particles. Preliminary results by EBSD show no evident effect of substrate crystallography on the crystallography of the final coating. Substantial topography was found to develop during the coating growth.
	Slides WEB1CO02 [3.299 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO02
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WEB1CO03	Surface Impurity Content Optimization to Maximize Q-factors of Superconducting Resonators	ion, cavity, SRF, factory	663
	M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov Fermilab, Batavia, Illinois, USA M. Checchin Illinois Institute of Technology, Chicago, Illlinois, USA J. Zasadzinski IIT, Chicago, Illinois, USA
	Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of trapped flux, depends on the mean free path. A systematic study of a variety of 1.3 GHz cavities with different surface treatments (EP, 120 ^°C bake and different N-doping) is carried out. A bell shaped trend appears for the range of mean free path studied. Over-doped cavities fall at the maximum of this curve defining the largest values of sensitivity. In addition, we have studied the trend of the BCS surface resistance contribution as a function of mean free path, showing that N-doped cavities follow close to the theoretical minimum. Adding these results together we show that the 2/6 N-doping treatment gives the highest Q-factor values at 2 K and 16 MV/m, as long as the magnetic field fully trapped during the cavity cooldown is lower than 10 mG.
	Slides WEB1CO03 [4.500 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO03
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPOB68

A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films

ion, laser, controls, electron

221

J. Musson, K. Macha, H.L. Phillips
JLab, Newport News, Virginia, USA
W. Cao, H. Elsayed-Ali
ODU, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University
Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB68

Export •

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

WEB1CO02

Investigation of Structural Development in the Two-Step Diffusion Coating of Nb3Sn on Niobium

ion, SRF, experiment, cavity

659

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA

Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475.
The potential for higher operating temperatures and increased accelerating gradient has attracted SRF researchers to Nb3Sn coatings on niobium for nearly 50 years. The two-step tin vapor diffusion: nucleation followed by deposition appears to be a promising technique to prepare Nb3Sn coatings on interior cavity surface. We have undertaken a fundamental materials study of the nucleation and deposition steps. Nucleation was accomplished within parameter ranges: 300 - 500 °C, 1 - 5 hrs duration, 5 mg - 1 g SnCl2 and 1 g Sn. The resulting deposit consists of (< 10%) coverage of tin particles, as determined by SEM/EDS, while XPS and SAM discovered extra tin film between these particles. Preliminary results by EBSD show no evident effect of substrate crystallography on the crystallography of the final coating. Substantial topography was found to develop during the coating growth.

Slides WEB1CO02 [3.299 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO02

Export •

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

WEB1CO03

Surface Impurity Content Optimization to Maximize Q-factors of Superconducting Resonators

ion, cavity, SRF, factory

663

M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA
M. Checchin
Illinois Institute of Technology, Chicago, Illlinois, USA
J. Zasadzinski
IIT, Chicago, Illinois, USA

Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of trapped flux, depends on the mean free path. A systematic study of a variety of 1.3 GHz cavities with different surface treatments (EP, 120 ^°C bake and different N-doping) is carried out. A bell shaped trend appears for the range of mean free path studied. Over-doped cavities fall at the maximum of this curve defining the largest values of sensitivity. In addition, we have studied the trend of the BCS surface resistance contribution as a function of mean free path, showing that N-doped cavities follow close to the theoretical minimum. Adding these results together we show that the 2/6 N-doping treatment gives the highest Q-factor values at 2 K and 16 MV/m, as long as the magnetic field fully trapped during the cavity cooldown is lower than 10 mG.

Slides WEB1CO03 [4.500 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB1CO03

Export •

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