LINAC2022 - List of Authors (Marks, H.S.)

Paper	Title	Page
THPOGE09	Split Thin Film SRF 6 GHz Cavities	814
	B.S. Sian, G. Burt, D.J. Seal Lancaster University, Lancaster, United Kingdom G. Burt, O.B. Malyshev, D.J. Seal, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.S. Marks Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Many current accelerators use cavities that are manufactured as two half cells that are electron beam welded together, the weld is across the peak surface current of the cavity. This weld can lead to large increases in surface resistance and limit the performance of thin film coated cavities. Many problems with the coating process for thin film Superconducting Radio Frequency (SRF) cavities are also due to this weld. Thin film SRF cavities can perform as well as bulk niobium cavities if the cavity is manufactured seamlessly, without any weld, as they have a more uniform surface, however, they are much more difficult and expensive to manufacture. A cavity with a split longitudinally, parallel to the direction of the electric field, would not need to be welded. These seamless cavities are easier to manufacture and coat. This opens the possibilities to coat with new materials and multilayer coatings. These cavities may allow SRF cavities to operate at significantly better parameters (higher quality factor and maximum accelerating field) than current state of the art cavities. This work discusses development and testing of longitudinally split seamless cavities at Daresbury Laboratory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE09
About •	Received ※ 25 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOGE10	RF Characterisation of Bulk Niobium and Thin Film Coated Planar Samples at 7.8 GHz	818
SUPCPA04	use link to see paper's listing under its alternate paper code
	D.J. Seal, G. Burt, O.B. Malyshev, B.S. Sian, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Burt, D.J. Seal, B.S. Sian Lancaster University, Lancaster, United Kingdom E. Chyhyrynets, C. Pira INFN/LNL, Legnaro (PD), Italy O. Hryhorenko, D. Longuevergne Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France O.B. Malyshev, E.A. Marshall, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.S. Marks Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Research is ongoing into the use of superconducting thin films to replace bulk niobium for future radio frequency (RF) cavities. A key part of this research requires measuring the RF properties of candidate films. However, coating and testing thin films on full-sized cavities is both costly and time-consuming. Instead, films are typically deposited on small, flat samples and characterised using a test cavity. A cost-effective facility for testing such samples has recently been built and commissioned at Daresbury Laboratory. The facility allows for low power surface resistance measurements at a resonant frequency of 7.8 GHz, temperatures down to 4 K and sample surface magnetic fields up to 1 mT. A brief overview of this facility as well as recent results from measurements of both bulk Nb and thin film coated samples will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE10
About •	Received ※ 11 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Split Thin Film SRF 6 GHz Cavities

814

B.S. Sian, G. Burt, D.J. Seal
Lancaster University, Lancaster, United Kingdom
G. Burt, O.B. Malyshev, D.J. Seal, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.S. Marks
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Many current accelerators use cavities that are manufactured as two half cells that are electron beam welded together, the weld is across the peak surface current of the cavity. This weld can lead to large increases in surface resistance and limit the performance of thin film coated cavities. Many problems with the coating process for thin film Superconducting Radio Frequency (SRF) cavities are also due to this weld. Thin film SRF cavities can perform as well as bulk niobium cavities if the cavity is manufactured seamlessly, without any weld, as they have a more uniform surface, however, they are much more difficult and expensive to manufacture. A cavity with a split longitudinally, parallel to the direction of the electric field, would not need to be welded. These seamless cavities are easier to manufacture and coat. This opens the possibilities to coat with new materials and multilayer coatings. These cavities may allow SRF cavities to operate at significantly better parameters (higher quality factor and maximum accelerating field) than current state of the art cavities. This work discusses development and testing of longitudinally split seamless cavities at Daresbury Laboratory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE09

About •

Received ※ 25 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022

Cite •

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

THPOGE10

RF Characterisation of Bulk Niobium and Thin Film Coated Planar Samples at 7.8 GHz

818

SUPCPA04

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

D.J. Seal, G. Burt, O.B. Malyshev, B.S. Sian, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Burt, D.J. Seal, B.S. Sian
Lancaster University, Lancaster, United Kingdom
E. Chyhyrynets, C. Pira
INFN/LNL, Legnaro (PD), Italy
O. Hryhorenko, D. Longuevergne
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
O.B. Malyshev, E.A. Marshall, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.S. Marks
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Research is ongoing into the use of superconducting thin films to replace bulk niobium for future radio frequency (RF) cavities. A key part of this research requires measuring the RF properties of candidate films. However, coating and testing thin films on full-sized cavities is both costly and time-consuming. Instead, films are typically deposited on small, flat samples and characterised using a test cavity. A cost-effective facility for testing such samples has recently been built and commissioned at Daresbury Laboratory. The facility allows for low power surface resistance measurements at a resonant frequency of 7.8 GHz, temperatures down to 4 K and sample surface magnetic fields up to 1 mT. A brief overview of this facility as well as recent results from measurements of both bulk Nb and thin film coated samples will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOGE10

About •

Received ※ 11 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

Cite •

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