ERL2019 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
WEPNEC17	Developments in Photocathode R&D at STFC Daresbury Laboratory: New Transverse Energy Spread Measurements and the Development of a Multi-Alkali Photocathode Preparation Facility	cathode, vacuum, electron, emittance	103
	L.B. Jones, B.L. Militsyn, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom L.B. Jones, D.P. Juarez-Lopez, B.L. Militsyn, T.C.Q. Noakes, L.A.J. Soomary, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom D.P. Juarez-Lopez, L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Photocathode R&D activity within ASTeC is focussed on further development of the tools required for the preparation and characterisation of high performance photocathodes for X-FELs. Our Transverse Energy Spread Spectrometer (TESS)* experimental facility can be used with III-V semiconductor, multi-alkali and metal photocathodes to measure transverse and longitudinal energy distributions of the emitted electrons. Recently TESS has been upgraded to increase the instrument sensitivity for operation with low QE materials under UV illumination. Our R&D facilities also include in-vacuum quantum efficiency measurement, XPS, STM, plus ex-vacuum optical and STM microscopy for surface metrology. Intrinsic photocathode emittance is affected by many factors including illumination wavelength and surface roughness. We present energy distribution measurements for electrons emitted from copper, niobium and zirconium photocathode samples with measured levels of surface roughness under illumination by wavelengths between 256 and 291 nm. We also present an update on progress to establish a multi-alkali photocathode preparation facility to support the CLARA** linear accelerator. * Proc. FEL’13, TUPPS033, 290-293 ** CLARA Conceptual Design Report J. Inst. 9 T05001
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC17
About •	paper received ※ 04 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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WEPNEC25	Research on Alkali Antimonide Photocathode Fabrication Recipe at PKU	cathode, emittance, vacuum, electron	120
	D.M. Ouyang, L.W. Feng, S. Huang, K.X. Liu, S.W. Quan, H.M. Xie, X.K. Zhang, S. Zhao PKU, Beijing, People’s Republic of China
	Low emittance, high QE and long lifetime photocathode is widely studied for X-ray Free Electron Laser (XFEL)and Energy Recovery Linacs (ERL) applications. A deposition system for alkali antimonide photocathode (K2CsSb, Cs3Sb etc.) is being commissioned at Peking University. In this paper, we present our experimental results on alkali antimonide photocathode with this deposition system. We successfully fabricated Cs3Sb photocathode on oxygen free copper, p-type Si (100) and Mo substrates with QE of 1.4%, 2.6% and 2.6% respectively.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC25
About •	paper received ※ 27 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WECOYBS04	Commissioning of theBERLinPro Diagnostics Line using Machine Learning Techniques	gun, booster, MMI, diagnostics	123
	B.C. Kuske HZB, Berlin, Germany A. Adelmann PSI, Villigen PSI, Switzerland
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association BERLinPro is an Energy Recovery Linac (ERL) project currently being set up at HZB, Berlin. Commissioning is planned for early 2020. HZB triggered and supported the development of release 2.0 of the particle tracking code OPAL, that is now also applicable to ERLs. OPAL is set up as an open source, highly parallel tracking code for large accelerator systems and many particles. Thus, it is idially suited to serve attempts of applying machine learning approaches to beam dynamics, as demonstrated in [1]. OPAL is used to calculate hundreds of randomized machines close to the commissioning optics of BERLinPro. This data base will be used to train a neural network, to establish a surrogate model of BERLinPro, much faster than any physical model including particle tracking. First steps, like the setup of the sampler and a sensitivity analysis of the resulting data are presented. The ultimate goal of this work is to use machine learning techniques during the commissioning of BERLinPro. Future steps are outlined. [1] A. Edelen, A. Adelmann, N. Neveu, Y. Huber, M. Frey, ’Machine Learning to enable orders of magnitude speedup in multi-objective optimization of particle accelerator systems’
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WECOYBS04
About •	paper received ※ 30 October 2019 paper accepted ※ 07 November 2019 issue date ※ 24 June 2020
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THCOYBS01	Metal and Semiconductor Photocathodes in HZDR SRF Gun	cathode, gun, SRF, cavity	142
	R. Xiang, A. Arnold, P. Murcek, J. Schaber, J. Teichert HZDR, Dresden, Germany J. Schaber TU Dresden, Dresden, Germany
	Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. Quality of photocathode in a photoinjector is one of the critical issues for the stability and reliability of the whole accelerator facility. In April 2013, the IR FEL lasing was demonstrated for the first time with the electron beam from the SRF gun with Cs2Te at HZDR. Cs2Te photocathode worked in SRF gun-I for more than one year without degradation. Currently, Mg photocathodes with QE up to 0.5% are applied in SRF Gun-II, generating e^- beam with bunch charge up to 300 pC in CW mode with sub-ps bunch length for the high power THz radiation. It is an excellent demonstration that SRF guns can work reliably in a high power user facility.
	Slides THCOYBS01 [3.868 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOYBS01
About •	paper received ※ 18 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THCOYBS02	High Charge High Current Beam From BNL 113 MHz SRF Gun	cathode, gun, cavity, electron	145
	I. Pinayev, I. Ben-Zvi, J.C. Brutus, M. Gaowei, T. Hayes, Y.C. Jing, V. Litvinenko, J. Ma, K. Mihara, G. Narayan, I. Petrushina, F. Severino, K. Shih, J. Skaritka, E. Wang, G. Wang, Y.H. Wu BNL, Upton, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA I. Petrushina, Y.H. Wu SUNY SB, Stony Brook, New York, USA K. Shih SBU, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 113 MHz superconducting gun is used an electron source for the coherent electron cooling experiment. The unique feature of the gun is that a photocathode is held at room temperature. It allowed to preserve the quantum efficiency of Cs2KSb cathode which is adversely affected by cryogenic temperatures. Relatively low frequency permitted fully realize the accelerating field gradient what in turn helps to achieve 10 nC charge and 0.3 microns normalized emittance. We present the achieved performance and operational experience as well.
	Slides THCOYBS02 [4.350 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOYBS02
About •	paper received ※ 03 September 2019 paper accepted ※ 08 July 2020 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FRCOXBS04	Status of the Control System for the Energy Recovery Linac BERLinPro at HZB	controls, EPICS, operation, linac	159
	T. Birke, P. Echevarria, D. Eichel, R. Fleischhauer, J.G. Hwang, G. Klemz, R. Müller, C. Schröder, E. Suljoti, A. Ushakov HZB, Berlin, Germany
	BERLinPro is an energy recovery linac (ERL) demonstrator project built at HZB. It features CW SRF technology for the low emittance, high brightness gun, the booster module and the recovery linac. Construction and civil engineering are mostly completed. Synchronized with the device integration the EPICS based control system is being set-up for testing, commissioning and finally operation. In the warm part of the accelerator technology is used that is already operational at BESSY and MLS (e.g. CAN-bus and PLC/OPCUA). New implementations like the machine protection system and novel major subsystems (e.g. LLRF, Cryo-Controls, photo cathode laser) need to be integrated. The first RF transmitters have been tested and commissioned. Around the time of this workshop the first segment of the accelerator is scheduled to become online. For commissioning and operation of the facility the standard set of EPICS tools form the back-bone. A set of generic python applications already developed at BESSY/MLS will be adapted to the specifics of BERLinPro. Scope and current project status are described in this paper.
	Slides FRCOXBS04 [11.021 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-FRCOXBS04
About •	paper received ※ 05 September 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

Developments in Photocathode R&D at STFC Daresbury Laboratory: New Transverse Energy Spread Measurements and the Development of a Multi-Alkali Photocathode Preparation Facility

cathode, vacuum, electron, emittance

103

L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
L.B. Jones, D.P. Juarez-Lopez, B.L. Militsyn, T.C.Q. Noakes, L.A.J. Soomary, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.P. Juarez-Lopez, L.A.J. Soomary, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Photocathode R&D activity within ASTeC is focussed on further development of the tools required for the preparation and characterisation of high performance photocathodes for X-FELs. Our Transverse Energy Spread Spectrometer (TESS)* experimental facility can be used with III-V semiconductor, multi-alkali and metal photocathodes to measure transverse and longitudinal energy distributions of the emitted electrons. Recently TESS has been upgraded to increase the instrument sensitivity for operation with low QE materials under UV illumination. Our R&D facilities also include in-vacuum quantum efficiency measurement, XPS, STM, plus ex-vacuum optical and STM microscopy for surface metrology. Intrinsic photocathode emittance is affected by many factors including illumination wavelength and surface roughness. We present energy distribution measurements for electrons emitted from copper, niobium and zirconium photocathode samples with measured levels of surface roughness under illumination by wavelengths between 256 and 291 nm. We also present an update on progress to establish a multi-alkali photocathode preparation facility to support the CLARA** linear accelerator.
* Proc. FEL’13, TUPPS033, 290-293
** CLARA Conceptual Design Report J. Inst. 9 T05001

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC17

About •

paper received ※ 04 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

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

WEPNEC25

Research on Alkali Antimonide Photocathode Fabrication Recipe at PKU

cathode, emittance, vacuum, electron

120

D.M. Ouyang, L.W. Feng, S. Huang, K.X. Liu, S.W. Quan, H.M. Xie, X.K. Zhang, S. Zhao
PKU, Beijing, People’s Republic of China

Low emittance, high QE and long lifetime photocathode is widely studied for X-ray Free Electron Laser (XFEL)and Energy Recovery Linacs (ERL) applications. A deposition system for alkali antimonide photocathode (K2CsSb, Cs3Sb etc.) is being commissioned at Peking University. In this paper, we present our experimental results on alkali antimonide photocathode with this deposition system. We successfully fabricated Cs3Sb photocathode on oxygen free copper, p-type Si (100) and Mo substrates with QE of 1.4%, 2.6% and 2.6% respectively.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC25

About •

paper received ※ 27 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

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

WECOYBS04

Commissioning of theBERLinPro Diagnostics Line using Machine Learning Techniques

gun, booster, MMI, diagnostics

123

B.C. Kuske
HZB, Berlin, Germany
A. Adelmann
PSI, Villigen PSI, Switzerland

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
BERLinPro is an Energy Recovery Linac (ERL) project currently being set up at HZB, Berlin. Commissioning is planned for early 2020. HZB triggered and supported the development of release 2.0 of the particle tracking code OPAL, that is now also applicable to ERLs. OPAL is set up as an open source, highly parallel tracking code for large accelerator systems and many particles. Thus, it is idially suited to serve attempts of applying machine learning approaches to beam dynamics, as demonstrated in [1]. OPAL is used to calculate hundreds of randomized machines close to the commissioning optics of BERLinPro. This data base will be used to train a neural network, to establish a surrogate model of BERLinPro, much faster than any physical model including particle tracking. First steps, like the setup of the sampler and a sensitivity analysis of the resulting data are presented. The ultimate goal of this work is to use machine learning techniques during the commissioning of BERLinPro. Future steps are outlined. [1] A. Edelen, A. Adelmann, N. Neveu, Y. Huber, M. Frey, ’Machine Learning to enable orders of magnitude speedup in multi-objective optimization of particle accelerator systems’

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WECOYBS04

About •

paper received ※ 30 October 2019 paper accepted ※ 07 November 2019 issue date ※ 24 June 2020

Export •

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

THCOYBS01

Metal and Semiconductor Photocathodes in HZDR SRF Gun

cathode, gun, SRF, cavity

142

R. Xiang, A. Arnold, P. Murcek, J. Schaber, J. Teichert
HZDR, Dresden, Germany
J. Schaber
TU Dresden, Dresden, Germany

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
Quality of photocathode in a photoinjector is one of the critical issues for the stability and reliability of the whole accelerator facility. In April 2013, the IR FEL lasing was demonstrated for the first time with the electron beam from the SRF gun with Cs2Te at HZDR. Cs2Te photocathode worked in SRF gun-I for more than one year without degradation. Currently, Mg photocathodes with QE up to 0.5% are applied in SRF Gun-II, generating e^- beam with bunch charge up to 300 pC in CW mode with sub-ps bunch length for the high power THz radiation. It is an excellent demonstration that SRF guns can work reliably in a high power user facility.

Slides THCOYBS01 [3.868 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOYBS01

About •

paper received ※ 18 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

Export •

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

THCOYBS02

High Charge High Current Beam From BNL 113 MHz SRF Gun

cathode, gun, cavity, electron

145

I. Pinayev, I. Ben-Zvi, J.C. Brutus, M. Gaowei, T. Hayes, Y.C. Jing, V. Litvinenko, J. Ma, K. Mihara, G. Narayan, I. Petrushina, F. Severino, K. Shih, J. Skaritka, E. Wang, G. Wang, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
I. Petrushina, Y.H. Wu
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 113 MHz superconducting gun is used an electron source for the coherent electron cooling experiment. The unique feature of the gun is that a photocathode is held at room temperature. It allowed to preserve the quantum efficiency of Cs2KSb cathode which is adversely affected by cryogenic temperatures. Relatively low frequency permitted fully realize the accelerating field gradient what in turn helps to achieve 10 nC charge and 0.3 microns normalized emittance. We present the achieved performance and operational experience as well.

Slides THCOYBS02 [4.350 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOYBS02

About •

paper received ※ 03 September 2019 paper accepted ※ 08 July 2020 issue date ※ 24 June 2020

Export •

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

FRCOXBS04

Status of the Control System for the Energy Recovery Linac BERLinPro at HZB

controls, EPICS, operation, linac

159

T. Birke, P. Echevarria, D. Eichel, R. Fleischhauer, J.G. Hwang, G. Klemz, R. Müller, C. Schröder, E. Suljoti, A. Ushakov
HZB, Berlin, Germany

BERLinPro is an energy recovery linac (ERL) demonstrator project built at HZB. It features CW SRF technology for the low emittance, high brightness gun, the booster module and the recovery linac. Construction and civil engineering are mostly completed. Synchronized with the device integration the EPICS based control system is being set-up for testing, commissioning and finally operation. In the warm part of the accelerator technology is used that is already operational at BESSY and MLS (e.g. CAN-bus and PLC/OPCUA). New implementations like the machine protection system and novel major subsystems (e.g. LLRF, Cryo-Controls, photo cathode laser) need to be integrated. The first RF transmitters have been tested and commissioned. Around the time of this workshop the first segment of the accelerator is scheduled to become online. For commissioning and operation of the facility the standard set of EPICS tools form the back-bone. A set of generic python applications already developed at BESSY/MLS will be adapted to the specifics of BERLinPro. Scope and current project status are described in this paper.

Slides FRCOXBS04 [11.021 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-FRCOXBS04

About •

paper received ※ 05 September 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020

Export •

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