SRF2021 - List of Authors (Gaitan, G.)

Paper	Title	Page
SUPTEV007	Development of a System for Coating SRF Cavities Using Remote Plasma CVD	129
	G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, M. Liepe, J. Sears, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the National Science Foundation under Grant No. PHY-1549132. Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. A vacuum quality monitor (VQM) is used to characterize the residual gases before coating. The CVD system has been designed and is currently under assembly and commissioning.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV007
About •	Received ※ 09 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 10 February 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEOTEV03	Toward Stoichiometric and Low-Surface-Roughness Nb₃Sn Thin Films via Direct Electrochemical Deposition	710
	Z. Sun, G. Gaitan, M. Ge, K. Howard, M. Liepe, T.E. Oseroff, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller, J.P. Sethna, N. Sitaraman Cornell University, Ithaca, New York, USA K.D. Dobson University of Delaware, Newark, Delaware, USA
	Reducing surface roughness and attaining stoichiometry of Nb₃Sn superconducting films are required to push their superheating field to the theoretical limit in SRF cavities. As such, we explore direct electrochemical processes that minimize involving foreign elements to deposit high-quality Sn, Nb, and NbxSn films on Nb and Cu surfaces. These films are then thermally annealed to Nb₃Sn. We find that smooth Sn pre-depositions via electroplating on Nb surfaces significantly reduce the average roughness of resultant Nb₃Sn to 65 nm, with a dramatic reduction in power intensity at medium special frequencies. Structural and superconducting properties demonstrate a Nb₃Sn A15 phase with a stoichiometry of 25 at% Sn. This process is being scaled-up to a 3.9 GHz cavity. Moreover, preliminary results on electroplating on Cu surface show that Nb plating undergoes a slow growth rate while subsequent Sn plating on the plated Nb surface can be controlled with varied thickness. The Nb plating process is currently being optimized.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOTEV03
About •	Received ※ 09 July 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 16 January 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Development of a System for Coating SRF Cavities Using Remote Plasma CVD

129

G. Gaitan, P. Bishop, A.T. Holic, G. Kulina, M. Liepe, J. Sears, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the National Science Foundation under Grant No. PHY-1549132.
Next-generation, thin-film surfaces employing Nb₃Sn, NbN, NbTiN, and other compound superconductors are destined to allow reaching superior RF performance levels in SRF cavities. Optimized, advanced deposition processes are required to enable high-quality films of such materials on large and complex-shaped cavities. For this purpose, Cornell University is developing a remote plasma-enhanced chemical vapor deposition (CVD) system that facilitates coating on complicated geometries with a high deposition rate. This system is based on a high-temperature tube furnace with a clean vacuum and furnace loading system. The use of plasma alongside reacting precursors will significantly reduce the required processing temperature and promote precursor decomposition. A vacuum quality monitor (VQM) is used to characterize the residual gases before coating. The CVD system has been designed and is currently under assembly and commissioning.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-SUPTEV007

About •

Received ※ 09 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 10 February 2022

Cite •

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

WEOTEV03

Toward Stoichiometric and Low-Surface-Roughness Nb₃Sn Thin Films via Direct Electrochemical Deposition

710

Z. Sun, G. Gaitan, M. Ge, K. Howard, M. Liepe, T.E. Oseroff, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, Z. Baraissov, M.M. Kelley, D.A. Muller, J.P. Sethna, N. Sitaraman
Cornell University, Ithaca, New York, USA
K.D. Dobson
University of Delaware, Newark, Delaware, USA

Reducing surface roughness and attaining stoichiometry of Nb₃Sn superconducting films are required to push their superheating field to the theoretical limit in SRF cavities. As such, we explore direct electrochemical processes that minimize involving foreign elements to deposit high-quality Sn, Nb, and NbxSn films on Nb and Cu surfaces. These films are then thermally annealed to Nb₃Sn. We find that smooth Sn pre-depositions via electroplating on Nb surfaces significantly reduce the average roughness of resultant Nb₃Sn to 65 nm, with a dramatic reduction in power intensity at medium special frequencies. Structural and superconducting properties demonstrate a Nb₃Sn A15 phase with a stoichiometry of 25 at% Sn. This process is being scaled-up to a 3.9 GHz cavity. Moreover, preliminary results on electroplating on Cu surface show that Nb plating undergoes a slow growth rate while subsequent Sn plating on the plated Nb surface can be controlled with varied thickness. The Nb plating process is currently being optimized.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SRF2021-WEOTEV03

About •

Received ※ 09 July 2021 — Revised ※ 09 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 16 January 2022

Cite •

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