LINAC2022 - List of Authors (Burt, G.)

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)

FRCTA01	Closing LINAC2022 – Announcement of LINAC2024
	P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Warrington, Cheshire, United Kingdom J.M. Byrd ANL, Lemont, Illinois, USA
	Closing and Farewell of LINAC2022 by the Conference Chair Peter McIntosh and the Scientific Programme Committee Chair Graeme Burt. Officially handing over the legacy LINAC ’Gavel and Block’ to the incoming conference chair John Byrd from Argonne National Laboratory, for the next LINAC conference which is to be held in Chicago in 2024.

	please see instructions how to view/control embeded videos
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI24	Monte Carlo Model of High-Voltage Conditioning and Operation	283
	W.L. Millar, W. Wuensch CERN, Meyrin, Switzerland G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	To synthesise the experimental results and theory pertaining to high-field phenomena, a model has been developed to simulate the conditioning and operation of high-field systems. By using a mesh-based method, the high-field conditioning of any arbitrary geometry and surface electric field distribution may be simulated for both RF and DC devices. Several phenomena observed in previous high-field tests such as the probabilistic behaviour of vacuum arcs and the inhomogeneous distribution of arc locations are described by this approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI24
About •	Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI26	Limits on Standing Wave Cavity Performance Due to Thermal Effects	287
SUPCRI02	use link to see paper's listing under its alternate paper code
	S.J. Smith, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	After an RF cavity has been designed, a thermal analysis is typically performed to assess the effects of RF heating on the operating frequency and field flatness. A multi-physics approach (coupled electromagnetic, thermal, and mechanical) is normally employed, sometimes combined with computational fluid dynamics (CFD) simulations to incorporate flowing water, which is used for cooling in normal conducting structures. Performing a CFD analysis can add significant time to the design process because of the long and complex simulations and instead, approximations of the heat transfer coefficients and inlet/outlet water temperature rises are made and used directly in the multi-physics analysis. In this work, we first explore the limits of these approximations, identifying when they apply and how accurate they are. We then investigate different pipe geometries and water flow rates to find the thermal limits from RF heating on cavity performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI26
About •	Received ※ 17 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA13	Pulsed DC High Field Measurements of Irradiated and Non-Irradiated Electrodes of Different Materials	441
SUPCJO07	use link to see paper's listing under its alternate paper code
	R.C. Peacock, G. Burt Lancaster University, Lancaster, United Kingdom G. Bellodi, S. Calatroni, C.F. Da Palma Serafim, A. Grudiev, A.M. Lombardi, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch CERN, Meyrin, Switzerland
	Beam loss occurs in Radio Frequency Quadrupoles (RFQ), and has been observed in the H⁻ linear accelerator Linac4 (L4) at CERN. To determine if beam loss can induce breakdowns, and to compare the robustness of different materials, tests have been done using pulsed high-voltage DC systems. Electrical breakdown phenomena and conditioning processes have been studied using these systems. Cathodes of different materials were irradiated with 1.2x10¹⁹ H⁻ p/cm², the estimated beam loss of the L4 RFQ over 10 days. The irradiated electrodes were installed in a system to observe if the irradiated area coincided with the breakdown locations, with pulsing parameters similar to the RFQ. Tests of irradiated and non-irradiated electrodes of the same material were done for comparison. The main difference observed was an increase in the number of breakdowns during the initial conditioning that returned to non-irradiated sample values with further running. Visual observations after irradiation show the beam centre and a halo the same diameter of the beam pipe. Breakdown clusters occur in the centre and halo regions, suggesting irradiation is not the only factor determining the breakdown probability.
	Poster TUPOPA13 [3.845 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA13
About •	Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 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)

FRCTA01

Closing LINAC2022 – Announcement of LINAC2024

P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J.M. Byrd
ANL, Lemont, Illinois, USA

Closing and Farewell of LINAC2022 by the Conference Chair Peter McIntosh and the Scientific Programme Committee Chair Graeme Burt. Officially handing over the legacy LINAC ’Gavel and Block’ to the incoming conference chair John Byrd from Argonne National Laboratory, for the next LINAC conference which is to be held in Chicago in 2024.

please see instructions how to view/control embeded videos

Cite •

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

MOPORI24

Monte Carlo Model of High-Voltage Conditioning and Operation

283

W.L. Millar, W. Wuensch
CERN, Meyrin, Switzerland
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

To synthesise the experimental results and theory pertaining to high-field phenomena, a model has been developed to simulate the conditioning and operation of high-field systems. By using a mesh-based method, the high-field conditioning of any arbitrary geometry and surface electric field distribution may be simulated for both RF and DC devices. Several phenomena observed in previous high-field tests such as the probabilistic behaviour of vacuum arcs and the inhomogeneous distribution of arc locations are described by this approach.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI24

About •

Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022

Cite •

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

MOPORI26

Limits on Standing Wave Cavity Performance Due to Thermal Effects

287

SUPCRI02

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

S.J. Smith, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

After an RF cavity has been designed, a thermal analysis is typically performed to assess the effects of RF heating on the operating frequency and field flatness. A multi-physics approach (coupled electromagnetic, thermal, and mechanical) is normally employed, sometimes combined with computational fluid dynamics (CFD) simulations to incorporate flowing water, which is used for cooling in normal conducting structures. Performing a CFD analysis can add significant time to the design process because of the long and complex simulations and instead, approximations of the heat transfer coefficients and inlet/outlet water temperature rises are made and used directly in the multi-physics analysis. In this work, we first explore the limits of these approximations, identifying when they apply and how accurate they are. We then investigate different pipe geometries and water flow rates to find the thermal limits from RF heating on cavity performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI26

About •

Received ※ 17 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022

Cite •

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

TUPOPA13

Pulsed DC High Field Measurements of Irradiated and Non-Irradiated Electrodes of Different Materials

441

SUPCJO07

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

R.C. Peacock, G. Burt
Lancaster University, Lancaster, United Kingdom
G. Bellodi, S. Calatroni, C.F. Da Palma Serafim, A. Grudiev, A.M. Lombardi, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch
CERN, Meyrin, Switzerland

Beam loss occurs in Radio Frequency Quadrupoles (RFQ), and has been observed in the H⁻ linear accelerator Linac4 (L4) at CERN. To determine if beam loss can induce breakdowns, and to compare the robustness of different materials, tests have been done using pulsed high-voltage DC systems. Electrical breakdown phenomena and conditioning processes have been studied using these systems. Cathodes of different materials were irradiated with 1.2x10¹⁹ H⁻ p/cm², the estimated beam loss of the L4 RFQ over 10 days. The irradiated electrodes were installed in a system to observe if the irradiated area coincided with the breakdown locations, with pulsing parameters similar to the RFQ. Tests of irradiated and non-irradiated electrodes of the same material were done for comparison. The main difference observed was an increase in the number of breakdowns during the initial conditioning that returned to non-irradiated sample values with further running. Visual observations after irradiation show the beam centre and a halo the same diameter of the beam pipe. Breakdown clusters occur in the centre and halo regions, suggesting irradiation is not the only factor determining the breakdown probability.

Poster TUPOPA13 [3.845 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA13

About •

Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 September 2022

Cite •

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