IPAC2022 - List of Authors (Liepe, M.)

Paper	Title	Page
TUPOTK035	CVD Nb₃Sn-on-Copper SRF Accelerator Cavities	1291
SUSPMF111	use link to see paper's listing under its alternate paper code
	G. Gaitan, P.N. Koufalis, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V.M. Arrieta, S.R. McNeal Ultramet, Pacoima, California, USA M. Liepe Cornell University, Ithaca, New York, USA
	Funding: This work is supported by the US Department of Energy SBIR program under grant number DE-SC0017902. Gabriel Gaitan is supported by the National Science Foundation under Grant No. PHY-1549132. Nb₃Sn is the most promising alternative material for achieving superior performance in Superconducting Radio-Frequency (SRF) cavities, compared to conventional bulk Nb cavities now used in accelerators. Chemical vapor deposition (CVD) is an alternative to the vapor diffusion-based Nb₃Sn growth technique predominantly used on bulk niobium cavities and may enable reaching superior RF performance at reduced cost. In collaboration with Cornell, Ultramet has developed CVD process capabilities and reactor designs to coat copper SRF cavities with thick and thin films of Nb and Nb₃Sn. In this paper, we present our latest research efforts on CVD Nb₃Sn-on-copper SRF cavities, including RF performance test results from two 1.3 GHz SRF cavities coated by Ultramet.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK035
About •	Received ※ 15 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOTK036	Study of Chemical Treatments to Optimize Niobium-3 Tin Growth in the Nucleation Phase	1295
	L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, Z. Sun Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Arias, M.M. Kelley, N. Sitaraman Cornell University, Ithaca, New York, USA
	Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams. Niobium-3 Tin (Nb₃Sn) is a high-potential material for next-generation Superconducting Radiofrequency (SRF) cavities in particle accelerators. The most promising growth method to date is based on vapor diffusion of tin into a niobium substrate with nucleating agent Tin Chloride (SnCl₂). Still, the current vapor diffusion recipe has significant room for realizing further performance improvement. We are investigating how different chemical treatments on the niobium substrate before coating influence the growth of a smooth and uniform Nb₃Sn layer. More specifically, this study focuses on the interaction between the SnCl₂ nucleating agent and the niobium surface oxides. We compare the effect of different chemical treatments with different pH values on the tin droplet distribution on niobium after the nucleation stage of coating. We also look at the effect that the nucleation temperature has on the smoothness and uniformity of the tin distribution, with the ultimate goal of optimizing the recipe to coat smooth Nb₃Sn cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK036
About •	Received ※ 12 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOTK037	Status Update on Cornell’s SRF Compact Conduction Cooled Cryomodule	1299
SUSPMF112	use link to see paper's listing under its alternate paper code
	N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, J. Sears, V.D. Shemelin, J. Turco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A new frontier in Superconducting RF (SRF) development is increasing the accessibility of SRF technology to small-scale accelerator operations which are used in various industrial or research applications. This is made possible by using commercial cryocoolers as a cooling source, which removes the need for expensive liquid cryogenics and their supporting infrastructure. Cornell University is currently developing a new cryomodule based on a conduction cooling scheme. This cryomodule will use two pulse tube cryocoolers in place of liquid cryogenics in order to cool the system. A new 1.3 GHz cavity has been designed with a set of four niobium rings welded at the equator and irises which allow for a direct thermal link between the cavity and cryocooler cold heads. The cavity will use two coaxial RF input couplers capable of delivering up to 100 kW total RF power for high-current beam operation. This coupler design was modified from the Cornell ERL injector couplers, including simplifications such as removing the cold RF window and most outer bellows, while retaining inner bellows for adjustable coupling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK037
About •	Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOTK038	Next Generation SRF Cavities at Cornell University	1303
SUSPMF113	use link to see paper's listing under its alternate paper code
	N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb₃Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038
About •	Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

TUPOTK035

CVD Nb₃Sn-on-Copper SRF Accelerator Cavities

1291

SUSPMF111

use link to see paper's listing under its alternate paper code

G. Gaitan, P.N. Koufalis, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V.M. Arrieta, S.R. McNeal
Ultramet, Pacoima, California, USA
M. Liepe
Cornell University, Ithaca, New York, USA

Funding: This work is supported by the US Department of Energy SBIR program under grant number DE-SC0017902. Gabriel Gaitan is supported by the National Science Foundation under Grant No. PHY-1549132.
Nb₃Sn is the most promising alternative material for achieving superior performance in Superconducting Radio-Frequency (SRF) cavities, compared to conventional bulk Nb cavities now used in accelerators. Chemical vapor deposition (CVD) is an alternative to the vapor diffusion-based Nb₃Sn growth technique predominantly used on bulk niobium cavities and may enable reaching superior RF performance at reduced cost. In collaboration with Cornell, Ultramet has developed CVD process capabilities and reactor designs to coat copper SRF cavities with thick and thin films of Nb and Nb₃Sn. In this paper, we present our latest research efforts on CVD Nb₃Sn-on-copper SRF cavities, including RF performance test results from two 1.3 GHz SRF cavities coated by Ultramet.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK035

About •

Received ※ 15 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022

Cite •

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

TUPOTK036

Study of Chemical Treatments to Optimize Niobium-3 Tin Growth in the Nucleation Phase

1295

L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, Z. Sun
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Arias, M.M. Kelley, N. Sitaraman
Cornell University, Ithaca, New York, USA

Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams.
Niobium-3 Tin (Nb₃Sn) is a high-potential material for next-generation Superconducting Radiofrequency (SRF) cavities in particle accelerators. The most promising growth method to date is based on vapor diffusion of tin into a niobium substrate with nucleating agent Tin Chloride (SnCl₂). Still, the current vapor diffusion recipe has significant room for realizing further performance improvement. We are investigating how different chemical treatments on the niobium substrate before coating influence the growth of a smooth and uniform Nb₃Sn layer. More specifically, this study focuses on the interaction between the SnCl₂ nucleating agent and the niobium surface oxides. We compare the effect of different chemical treatments with different pH values on the tin droplet distribution on niobium after the nucleation stage of coating. We also look at the effect that the nucleation temperature has on the smoothness and uniformity of the tin distribution, with the ultimate goal of optimizing the recipe to coat smooth Nb₃Sn cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK036

About •

Received ※ 12 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

Cite •

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

TUPOTK037

Status Update on Cornell’s SRF Compact Conduction Cooled Cryomodule

1299

SUSPMF112

use link to see paper's listing under its alternate paper code

N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, J. Sears, V.D. Shemelin, J. Turco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A new frontier in Superconducting RF (SRF) development is increasing the accessibility of SRF technology to small-scale accelerator operations which are used in various industrial or research applications. This is made possible by using commercial cryocoolers as a cooling source, which removes the need for expensive liquid cryogenics and their supporting infrastructure. Cornell University is currently developing a new cryomodule based on a conduction cooling scheme. This cryomodule will use two pulse tube cryocoolers in place of liquid cryogenics in order to cool the system. A new 1.3 GHz cavity has been designed with a set of four niobium rings welded at the equator and irises which allow for a direct thermal link between the cavity and cryocooler cold heads. The cavity will use two coaxial RF input couplers capable of delivering up to 100 kW total RF power for high-current beam operation. This coupler design was modified from the Cornell ERL injector couplers, including simplifications such as removing the cold RF window and most outer bellows, while retaining inner bellows for adjustable coupling.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK037

About •

Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022

Cite •

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

TUPOTK038

Next Generation SRF Cavities at Cornell University

1303

SUSPMF113

use link to see paper's listing under its alternate paper code

N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb₃Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038

About •

Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022

Cite •

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