LINAC2022 - List of Authors (Valizadeh, R.)

Paper	Title	Page
THPOJO09	Status of CLARA at Daresbury Laboratory	711
	D. Angal-Kalinin, A.R. Bainbridge, A.D. Brynes, R.K. Buckley, S.R. Buckley, H.M. Castañeda Cortés, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, A.J. Gilfellon, A.R. Goulden, J. Henderson, S. Hitchen, F. Jackson, C.R. Jenkins, M.A. Johnson, J.K. Jones, N.Y. Joshi, M.P. King, S.L. Mathisen, J.W. McKenzie, R. Mclean, K.J. Middleman, B.L. Militsyn, K.T. Morrow, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, W.A. Okell, H.L. Owen, T.H. Pacey, A.E. Pollard, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.R. Bainbridge, A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, C.R. Jenkins, K.J. Middleman, A.J. Moss, B.D. Muratori, H.L. Owen, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.J. Vick, A.E. Wheelhouse Cockcroft Institute, Warrington, Cheshire, United Kingdom A.D. Brynes Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy R.J. Cash, R.F. Clarke, M. Colling, G. Cox, B.D. Fell, S.A. Griffiths, M.D. Hancock, T. Hartnett, J.P. Hindley, C. Hodgkinson, G. Marshall, A. Oates, A.J. Vick, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J. Henderson Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The Front End of CLARA has been used for user exploitation programme from 2018. The second exploitation period in 2021-22 provided a range of beam parameters to 8 user experiments. We report on the status, further machine development, and future plans for CLARA including Full Energy Beam Exploitation (FEBE) beamline which will provide 250 MeV/c high brightness beam for novel experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO09
About •	Received ※ 19 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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)

THPOJO10	RF Design and Characterisation of the CLARA 10 Hz Gun with Photocathode Load/Lock Upgrade	715
	A.J. Gilfellon, L.S. Cowie, T.J. Jones, B.L. Militsyn, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The 2.5 cell S-band 10 Hz repetition rate electron gun (Gun-10) for the CLARA (Compact Linear Accelerator for Research and Applications) facility underwent an upgrade during the scheduled shutdown period during the summer of 2019. The existing photocathode/back plate was replaced by a new back plate with interchangeable photocathode socket connected to a load/lock system capable of rapid exchanges of photocathode plugs. Here we outline motivation and RF design of the back plate and also detail the low power RF testing and characterisation of the upgraded gun in terms of the unloaded quality factor, the RF power coupling match, the percent field flatness and the operating frequency of the cavity, calculated from the frequency measured in the laboratory. Finally, via simulations using CST MWS and ASTRA, we produce a dependence of expected beam momentum vs forward power that we predict the gun will deliver once it goes back online.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO10
About •	Received ※ 25 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPORI15	Operation of the CLARA Linear Accelerator with 2.5 Cell 10 Hz Photocathode Gun with Interchangeable Photocathodes	854
	B.L. Militsyn, D. Angal-Kalinin, A.R. Bainbridge, L.S. Cowie, A.J. Gilfellon, F. Jackson, N.Y. Joshi, K.J. Middleman, K.T. Morrow, T.C.Q. Noakes, M.D. Roper, R. Valizadeh, D.A. Walsh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash, B.D. Fell, T.J. Jones, A.J. Vick STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	During commissioning and operation run in 2021-2022 the photoinjector of the CLARA-VELA facility a 2.5 cell cavity S-band photocathode gun originally developed for the APEX experiment was used. The copper back wall of the cavity also served as the gun photocathode. In order to reduce significant time required for replacement and/or reactivation of the photocathode and improve the flexibility of the injector the gun has been upgraded for operation with DESY/INFN style interchangeable photocathodes. This upgrade included a new design of the cavity back wall to accommodate the photocathode socket and equipping the gun with a load-lock system. Modification of the gun also required replacement of the bucking coil, which zeros field in the photocathode emission plane. After the upgrade, the gun was commissioned and then operated with a hybrid Cu/Mo photocathode during the last two years. During winter-spring 2022 experimental run the gun steadily operated with a cathode field of 60 MV/m, limited by the RF power available and with an off-centre diamond turned photocathode which delivered stable bunches with a charge of 100 pC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI15
About •	Received ※ 24 August 2022 — Revised ※ 08 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Status of CLARA at Daresbury Laboratory

711

D. Angal-Kalinin, A.R. Bainbridge, A.D. Brynes, R.K. Buckley, S.R. Buckley, H.M. Castañeda Cortés, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, A.J. Gilfellon, A.R. Goulden, J. Henderson, S. Hitchen, F. Jackson, C.R. Jenkins, M.A. Johnson, J.K. Jones, N.Y. Joshi, M.P. King, S.L. Mathisen, J.W. McKenzie, R. Mclean, K.J. Middleman, B.L. Militsyn, K.T. Morrow, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, W.A. Okell, H.L. Owen, T.H. Pacey, A.E. Pollard, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.R. Bainbridge, A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, C.R. Jenkins, K.J. Middleman, A.J. Moss, B.D. Muratori, H.L. Owen, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.J. Vick, A.E. Wheelhouse
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.D. Brynes
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
R.J. Cash, R.F. Clarke, M. Colling, G. Cox, B.D. Fell, S.A. Griffiths, M.D. Hancock, T. Hartnett, J.P. Hindley, C. Hodgkinson, G. Marshall, A. Oates, A.J. Vick, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J. Henderson
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The Front End of CLARA has been used for user exploitation programme from 2018. The second exploitation period in 2021-22 provided a range of beam parameters to 8 user experiments. We report on the status, further machine development, and future plans for CLARA including Full Energy Beam Exploitation (FEBE) beamline which will provide 250 MeV/c high brightness beam for novel experiments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO09

About •

Received ※ 19 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 15 September 2022

Cite •

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

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)

THPOJO10

RF Design and Characterisation of the CLARA 10 Hz Gun with Photocathode Load/Lock Upgrade

715

A.J. Gilfellon, L.S. Cowie, T.J. Jones, B.L. Militsyn, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The 2.5 cell S-band 10 Hz repetition rate electron gun (Gun-10) for the CLARA (Compact Linear Accelerator for Research and Applications) facility underwent an upgrade during the scheduled shutdown period during the summer of 2019. The existing photocathode/back plate was replaced by a new back plate with interchangeable photocathode socket connected to a load/lock system capable of rapid exchanges of photocathode plugs. Here we outline motivation and RF design of the back plate and also detail the low power RF testing and characterisation of the upgraded gun in terms of the unloaded quality factor, the RF power coupling match, the percent field flatness and the operating frequency of the cavity, calculated from the frequency measured in the laboratory. Finally, via simulations using CST MWS and ASTRA, we produce a dependence of expected beam momentum vs forward power that we predict the gun will deliver once it goes back online.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO10

About •

Received ※ 25 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022

Cite •

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

THPORI15

Operation of the CLARA Linear Accelerator with 2.5 Cell 10 Hz Photocathode Gun with Interchangeable Photocathodes

854

B.L. Militsyn, D. Angal-Kalinin, A.R. Bainbridge, L.S. Cowie, A.J. Gilfellon, F. Jackson, N.Y. Joshi, K.J. Middleman, K.T. Morrow, T.C.Q. Noakes, M.D. Roper, R. Valizadeh, D.A. Walsh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash, B.D. Fell, T.J. Jones, A.J. Vick
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

During commissioning and operation run in 2021-2022 the photoinjector of the CLARA-VELA facility a 2.5 cell cavity S-band photocathode gun originally developed for the APEX experiment was used. The copper back wall of the cavity also served as the gun photocathode. In order to reduce significant time required for replacement and/or reactivation of the photocathode and improve the flexibility of the injector the gun has been upgraded for operation with DESY/INFN style interchangeable photocathodes. This upgrade included a new design of the cavity back wall to accommodate the photocathode socket and equipping the gun with a load-lock system. Modification of the gun also required replacement of the bucking coil, which zeros field in the photocathode emission plane. After the upgrade, the gun was commissioned and then operated with a hybrid Cu/Mo photocathode during the last two years. During winter-spring 2022 experimental run the gun steadily operated with a cathode field of 60 MV/m, limited by the RF power available and with an off-centre diamond turned photocathode which delivered stable bunches with a charge of 100 pC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI15

About •

Received ※ 24 August 2022 — Revised ※ 08 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022

Cite •

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