SRF2017 - List of Authors (Arias, T.)

Paper	Title	Page
WEXA01	High Performance Nb3Sn Cavities	667
	D.L. Hall, M. Liepe, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, P. Cueva, D. Liarte, D.A. Muller, J.P. Sethna, N. Sitaraman Cornell University, Ithaca, New York, USA
	In recent years, 1.3 GHz single-cell cavities coated with Nb3Sn at Cornell University have repeatedly demonstrated quality factors of >10¹⁰ at 4.2 K and >15 MV/m. Ongoing research is currently focussed on the impact of intrinsic and extrinsic factors that limit the quality factor and quench field in these cavities. New single-cell cavities have been commissioned to enable further exploration of the coating parameter space. Experimental studies on both cavities and sample coupons have been supplemented by theoretical work done on layer growth, trapped vortex motion and flux entry. In this paper, we provide a comprehensive overview of the latest developments on Nb3Sn cavities, including work conducted in collaboration with the new NSF Centre for Bright Beams, with a brief summary on work being done in the field at large.
	Slides WEXA01 [10.681 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-WEXA01
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THPB040	SRF Theory Developments from the Center for Bright Beams	835
	D. Liarte, T. Arias, M. Liepe, J.P. Sethna, N. Sitamaran Cornell University, Ithaca, New York, USA D.L. Hall Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A.R. Pack, M.K. Transtrum Brigham Young University, Provo, USA
	Funding: This work was supported by the US National Science Foundation under Award OIA-1549132, the Center for Bright Beams. We present theoretical studies of SRF materials from the Center for Bright Beams. First, we discuss the effects of disorder, inhomogeneities, and materials anisotropy on the maximum parallel surface field that a superconductor can sustain in an SRF cavity, using linear stability in conjunction with Ginzburg-Landau and Eilenberger theory. We connect our disorder mediated vortex nucleation model to current experimental developments of Nb3Sn and other cavity materials. Second, we use time-dependent Ginzburg-Landau simulations to explore the role of inhomogeneities in nucleating vortices, and discuss the effects of trapped magnetic flux on the residual resistance of weakly-pinned Nb3Sn cavities. Third, we present first-principles density-functional theory (DFT) calculations to uncover and characterize the key fundamental materials processes underlying the growth of Nb3Sn. Our calculations indicate that the observed tin-depleted regions may be the direct result of an exothermic reaction between Nb3Sn and Nb at the growing Nb/Nb3Sn interface. We suggest new growth protocols to mitigate the formation of tin depleted regions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB040
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

High Performance Nb3Sn Cavities

667

D.L. Hall, M. Liepe, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, P. Cueva, D. Liarte, D.A. Muller, J.P. Sethna, N. Sitaraman
Cornell University, Ithaca, New York, USA

In recent years, 1.3 GHz single-cell cavities coated with Nb3Sn at Cornell University have repeatedly demonstrated quality factors of >10¹⁰ at 4.2 K and >15 MV/m. Ongoing research is currently focussed on the impact of intrinsic and extrinsic factors that limit the quality factor and quench field in these cavities. New single-cell cavities have been commissioned to enable further exploration of the coating parameter space. Experimental studies on both cavities and sample coupons have been supplemented by theoretical work done on layer growth, trapped vortex motion and flux entry. In this paper, we provide a comprehensive overview of the latest developments on Nb3Sn cavities, including work conducted in collaboration with the new NSF Centre for Bright Beams, with a brief summary on work being done in the field at large.

Slides WEXA01 [10.681 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-WEXA01

Export •

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

THPB040

SRF Theory Developments from the Center for Bright Beams

835

D. Liarte, T. Arias, M. Liepe, J.P. Sethna, N. Sitamaran
Cornell University, Ithaca, New York, USA
D.L. Hall
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A.R. Pack, M.K. Transtrum
Brigham Young University, Provo, USA

Funding: This work was supported by the US National Science Foundation under Award OIA-1549132, the Center for Bright Beams.
We present theoretical studies of SRF materials from the Center for Bright Beams. First, we discuss the effects of disorder, inhomogeneities, and materials anisotropy on the maximum parallel surface field that a superconductor can sustain in an SRF cavity, using linear stability in conjunction with Ginzburg-Landau and Eilenberger theory. We connect our disorder mediated vortex nucleation model to current experimental developments of Nb3Sn and other cavity materials. Second, we use time-dependent Ginzburg-Landau simulations to explore the role of inhomogeneities in nucleating vortices, and discuss the effects of trapped magnetic flux on the residual resistance of weakly-pinned Nb3Sn cavities. Third, we present first-principles density-functional theory (DFT) calculations to uncover and characterize the key fundamental materials processes underlying the growth of Nb3Sn. Our calculations indicate that the observed tin-depleted regions may be the direct result of an exothermic reaction between Nb3Sn and Nb at the growing Nb/Nb3Sn interface. We suggest new growth protocols to mitigate the formation of tin depleted regions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB040

Export •

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