IPAC2018 - List of Authors (Valizadeh, R.)

Paper	Title	Page
THPAL086	Superconducting Thin Film RF Measurements	3856
	P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt, L. Gurran Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom L. Gurran, T. Junginger Lancaster University, Lancaster, United Kingdom
	As part of an ongoing programme of SRF Thin Films development, a radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The resonator has now been used for measurements on Thin Film samples. Results from a test on a sample previously tested at Cornell University are presented. In order to simplify the measurements and achieve a faster turnaround, the experiment will be moved to a new cryostat fitted with a cryocooler. This will limit the measurements to low power only, but will allow a much faster sorting of samples to identify those that would benefit from further investigation. A description of the system and initial results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086
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THPAL098	Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating	3869
	Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper Loughborough University, Leicestershre, United Kingdom A.N. Hannah, O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL098
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THPMK059	Commissioning of Front End of CLARA Facility at Daresbury Laboratory	4426
	D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.J. Price, 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, T.M. Weston, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom R.J. Cash, R.F. Clarke, G. Cox, G.P. Diakun, A. Gallagher, K.D. Gleave, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility being developed at STFC Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. The installation of the Front End (FE) section of CLARA, a S-bend merging with existing VELA (Versatile Electron Linear Accelerator) beam line and installation of a high repetition rate RF gun on VELA was completed in 2017. First beam commissioning results and high level software developments are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK059
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THPMK063	Photocathode Preparation and Characteristics of the Electron Source for the VELA/CLARA Facility	4442
	T.C.Q. Noakes, D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, M.D. Roper, E.W. Snedden, R. Valizadeh, D.A. Walsh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The VELA and CLARA front end accelerators at Daresbury are test facilities with a focus on FEL research and industrial applications of electron beams. Recently the CLARA injector has been commissioned with acceleration of beam to 50 MeV. For several years a normal conducting 2.5 cell S-band cavity RF gun operated at up to 80 MV/m has been used as the electron source for both VELA and CLARA. For further beam acceleration an S-band travelling wave 2m long cavity has been used. The gun has used several different copper cathodes throughout its operational life, employing different preparation techniques. Oxygen plasma treatment is a well-known procedure for removing hydrocarbon contamination from surfaces whereas Argon plasma treatment also removes contaminants and typically leaves a thinner oxide at the surface. In this study we compare dark current (from field emission), as measured directly after the gun, for these alternate surface preparations and also present results from post-use electron microscopy analysis of the photocathodes. Electromagnetic simulations are used to help explain the results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK063
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THPAL089	Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing	3859
	O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Pizzol The University of Liverpool, Liverpool, United Kingdom
	An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089
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THPAL092	Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples	3862
	O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom Sirvinskaite, R. Sirvinskaite Loughborough University, Loughborough, Leicestershire, United Kingdom
	The pumping properties of the NEG coated vacuum chambers play an important role in the efficiency of vac-uum system of accelerators. The sticking probability of the NEG films is one the most important parameters to characterise the pumping properties of the NEG coated vacuum chambers. In order to investigate the NEG film sticking probability, Test Particle Monte-Carlo (TPMC) models were used. The models were based on the design of the installed experimental setup in ASTeC Vacuum Science group laboratory at Daresbury Laboratory (DL). The results of the simulations have been used for inter-preting the results of the measurements in the experi-mental setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092
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THPAL095	Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory	3865
	A.N. Hannah, J.A. Conlon, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V. R. Dhanak The University of Liverpool, Liverpool, United Kingdom L.B. Jones, B.L. Militsyn Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Lederer DESY Zeuthen, Zeuthen, Germany S. Lederer DESY, Hamburg, Germany
	The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10^-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL095
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THPAL133	LASE Surfaces for Mitigation of Electron Cloud in Accelerators	3958
SUSPL084	use link to see paper's listing under its alternate paper code
	B.S. Sian UMAN, Manchester, United Kingdom O.B. Malyshev, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133
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Paper

Title

Page

Superconducting Thin Film RF Measurements

3856

P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
L. Gurran, T. Junginger
Lancaster University, Lancaster, United Kingdom

As part of an ongoing programme of SRF Thin Films development, a radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The resonator has now been used for measurements on Thin Film samples. Results from a test on a sample previously tested at Cornell University are presented. In order to simplify the measurements and achieve a faster turnaround, the experiment will be moved to a new cryostat fitted with a cryocooler. This will limit the measurements to low power only, but will allow a much faster sorting of samples to identify those that would benefit from further investigation. A description of the system and initial results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086

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THPAL098

Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating

3869

Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper
Loughborough University, Leicestershre, United Kingdom
A.N. Hannah, O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL098

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THPMK059

Commissioning of Front End of CLARA Facility at Daresbury Laboratory

4426

D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.J. Price, 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, T.M. Weston, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.J. Cash, R.F. Clarke, G. Cox, G.P. Diakun, A. Gallagher, K.D. Gleave, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility being developed at STFC Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. The installation of the Front End (FE) section of CLARA, a S-bend merging with existing VELA (Versatile Electron Linear Accelerator) beam line and installation of a high repetition rate RF gun on VELA was completed in 2017. First beam commissioning results and high level software developments are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK059

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THPMK063

Photocathode Preparation and Characteristics of the Electron Source for the VELA/CLARA Facility

4442

T.C.Q. Noakes, D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, M.D. Roper, E.W. Snedden, R. Valizadeh, D.A. Walsh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The VELA and CLARA front end accelerators at Daresbury are test facilities with a focus on FEL research and industrial applications of electron beams. Recently the CLARA injector has been commissioned with acceleration of beam to 50 MeV. For several years a normal conducting 2.5 cell S-band cavity RF gun operated at up to 80 MV/m has been used as the electron source for both VELA and CLARA. For further beam acceleration an S-band travelling wave 2m long cavity has been used. The gun has used several different copper cathodes throughout its operational life, employing different preparation techniques. Oxygen plasma treatment is a well-known procedure for removing hydrocarbon contamination from surfaces whereas Argon plasma treatment also removes contaminants and typically leaves a thinner oxide at the surface. In this study we compare dark current (from field emission), as measured directly after the gun, for these alternate surface preparations and also present results from post-use electron microscopy analysis of the photocathodes. Electromagnetic simulations are used to help explain the results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK063

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THPAL089

Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing

3859

O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Pizzol
The University of Liverpool, Liverpool, United Kingdom

An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089

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THPAL092

Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples

3862

O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Sirvinskaite, R. Sirvinskaite
Loughborough University, Loughborough, Leicestershire, United Kingdom

The pumping properties of the NEG coated vacuum chambers play an important role in the efficiency of vac-uum system of accelerators. The sticking probability of the NEG films is one the most important parameters to characterise the pumping properties of the NEG coated vacuum chambers. In order to investigate the NEG film sticking probability, Test Particle Monte-Carlo (TPMC) models were used. The models were based on the design of the installed experimental setup in ASTeC Vacuum Science group laboratory at Daresbury Laboratory (DL). The results of the simulations have been used for inter-preting the results of the measurements in the experi-mental setup.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092

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THPAL095

Metal Photocathodes Preparation for Compact Linear Accelerator at Daresbury Laboratory

3865

A.N. Hannah, J.A. Conlon, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V. R. Dhanak
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, B.L. Militsyn
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Lederer
DESY Zeuthen, Zeuthen, Germany
S. Lederer
DESY, Hamburg, Germany

The photoinjector of the CLARA FEL test facility Front End at Daresbury Laboratory is based on a S-band 10 Hz photocathode RF-gun operating with a copper photocath-ode which is driven by the third harmonic of a Ti:Sapphire laser (266 nm). The main aim of this study was to establish a procedure to prepare the Cu surface prior to installation so a Quantum Efficiency (QE) of 10^-5 or higher can be achieved at laser power density below the ablation threshold of copper. The best results have been obtained by ex-situ chemical cleaning. This removed the surface oxide layer whilst at the same time producing a surface buffer layer. This inhibited the regrowth of native oxide for up to a week when exposed to normal ambient atmospheric conditions. With either chemical cleaning or Ar plasma cleaning after heating the sample in-situ to 150 °C for 90 minutes or 250 °C for 40 hours, almost all of the surface oxide was removed. For these surfaces a QE of 4.10-5 or better was measured. Oxygen plasma cleaning at 100% and 20% power produced CuO layer with surface carbon contaminant to 3 atomic %, however in-situ thermal cycling resulted in at best a QE of 3·10-6.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL095

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THPAL133

LASE Surfaces for Mitigation of Electron Cloud in Accelerators

3958

SUSPL084

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

B.S. Sian
UMAN, Manchester, United Kingdom
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133

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