MC2: Photon Sources and Electron Accelerators
T02: Electron Sources

Paper	Title	Page
THPOST046	CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG)	2544
SUSPMF021	use link to see paper's listing under its alternate paper code
	G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai, A. Suraj UCLA, Los Angeles, California, USA
	Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409 Pro­duc­ing higher bright­ness beams at the cath­ode is one of the main fo­cuses for fu­ture elec­tron beam ap­pli­ca­tions. For pho­to­cath­odes op­er­at­ing close to their emis­sion thresh­old, the cath­ode lat­tice tem­per­a­ture be­gins to dom­i­nate the min­i­mum achiev­able in­trin­sic emit­tance. At UCLA, we are de­sign­ing a ra­diofre­quency (RF) test bed for mea­sur­ing the tem­per­a­ture de­pen­dence of the mean trans­verse en­ergy (MTE) and quan­tum ef­fi­ciency for a num­ber of can­di­date cath­ode ma­te­ri­als. We in­tend to quan­tify the at­tain­able bright­ness im­prove­ments at the cath­ode from cryo­genic op­er­a­tion and es­tab­lish a proof-of-prin­ci­ple cryo­genic RF gun for fu­ture stud­ies of a 1.6-cell cryo­genic pho­toin­jec­tor for the UCLA ultra com­pact XFEL con­cept (UC-XFEL). The test bed will use a C-band 0.5-cell RF gun de­signed to op­er­ate down to 45 K, pro­duc­ing an on-axis ac­cel­er­at­ing field of 120 MV/m. The cryo­genic sys­tem uses con­duc­tion cool­ing and a load-lock sys­tem is being de­signed for trans­port and stor­age of air-sen­si­tive high bright­ness cath­odes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST046
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 01 July 2022
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THPOPT005	Field Enhanced, Compact S-Band Gun Employing a Pin Cathode	2567
SUSPMF020	use link to see paper's listing under its alternate paper code
	R. Bazrafshan, T. Rohwer Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany M. Fakhari, K. Flöttmann, F.X. Kaernter DESY, Hamburg, Germany N.H. Matlis CFEL, Hamburg, Germany
	S-band RF-guns are highly de­vel­oped for pro­duc­tion of low emit­tance rel­a­tivis­tic elec­tron bunches, but need pow­er­ful kly­strons for dri­ving. Here, we pre­sent the de­sign and first ex­per­i­men­tal tests of a com­pact S-band gun, which can ac­cel­er­ate elec­trons up to 180 keV pow­ered by only 10 kW from a com­pact rack-mount­able solid-state am­pli­fier. A pin-cath­ode is used to en­hance the RF elec­tric field on the cath­ode up to 100 MV/m as in large-scale S-band guns. An elec­tron bunch is gen­er­ated through pho­toe­mis­sion off a flat cop­per sur­face on the pin ex­cited by a UV laser pulse fol­lowed by a fo­cus­ing so­le­noid pro­duc­ing a low emit­tance bunch with 0.1 mm mrad trans­verse emit­tance for up to 100 fC bunch charge. We are cur­rently in the con­di­tion­ing phase of the gun and first ex­per­i­ments show good agree­ment with sim­u­la­tions. The com­pact gun will serve three pur­poses: (i) it can be used di­rectly for ul­tra­fast elec­tron dif­frac­tion; (ii) as an in­jec­tor into a THz booster pro­duc­ing 0.3MeV to 2 MeV elec­tron bunches for ul­tra­fast elec­tron dif­frac­tion; (iii) The sys­tem in (ii) serves as an in­jec­tor into a THz lin­ear ac­cel­er­a­tor pro­duc­ing a 20 MeV beam for the AXSIS X-ray source pro­ject.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT005
About •	Received ※ 21 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 10 July 2022
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THPOPT019	Multi-Alkali Antimonide Photocathode Development for High Brightness Beams	2610
	S. Mistry, T. Kamps, J. Kühn, C. Wang HZB, Berlin, Germany T. Kamps HU Berlin, Berlin, Germany C. Wang University Siegen, Siegen, Germany
	Funding: This work is funded by the DFG CO 1509/10-1 | MI 2917/1-1 Pho­to­cath­ode R&D at the Helmholtz-Zen­trum Berlin (HZB) is dri­ven by the mo­ti­va­tion to pro­duce high bright­ness elec­tron beams for the SRF pho­toin­jec­tor test fa­cil­ity, Sealab/ bERLinPro. Multi-al­kali an­ti­monides are the choice pho­to­cath­ode ma­te­r­ial due to high quan­tum ef­fi­ciency (QE) and low in­trin­sic emit­tance in the vis­i­ble range. In this work a more ro­bust al­ter­na­tive to the tried and tested Cs-K-Sb is con­sid­ered. Na-K-Sb of­fers sim­i­lar ad­van­tages to Cs-K-Sb in­clud­ing, high QE at green wave­lengths but more­over, it of­fers ex­cel­lent sta­bil­ity at el­e­vated tem­per­a­tures. This prop­erty could lengthen the cath­ode life­time by en­hanc­ing the ro­bust­ness of the pho­to­cath­ode in­side the SRF gun. In this work, a sta­tus re­port show­cas­ing first re­sults to­wards the de­vel­op­ment of a growth pro­ce­dure for Na-K-Sb is pre­sented by means of spec­tral re­sponse and XPS mea­sure­ments con­ducted in the HZB pho­to­cath­ode lab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT019
About •	Received ※ 03 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 04 July 2022
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THPOPT020	Status and Plans for the New CLS Electron Source Lab	2614
	M.J. Boland, D. Bertwistle, F. Le Pimpec CLS, Saskatoon, Saskatchewan, Canada X.F.D. Stragier TUE, Eindhoven, The Netherlands
	The Cana­dian Light Source (CLS) has re­cently cre­ated a new Elec­tron Source Lab (ESL) that can run in­de­pen­dently from user op­er­a­tions. A sec­tion of the old Saskatchewan Ac­cel­er­a­tor Lab­o­ra­tory ex­per­i­men­tal nu­clear physics tun­nels has been re­built with new shield­ing and a sep­a­rate en­trance. The lab­o­ra­tory will be used to pre­pare an op­er­a­tional spare elec­tron gun for the 250 MeV linac. In ad­di­tion, there are plans to de­velop RF guns for a fu­ture branch line to in­ject into the linac and for pos­si­ble short pulse pro­duc­tion. This paper will give an overview of the ESL space and the first elec­tron guns which plan to be in­stalled.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT020
About •	Received ※ 16 June 2022 — Revised ※ 29 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 08 July 2022
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THPOPT022	Study on QE Evolution of Cs2Te Photocathodes in ELBE SRF Gun-II	2617
	R. Xiang, A. Arnold, S. Ma, P. Michel, P. Murcek, A.A. Ryzhov, J. Schaber, J. Teichert, P.Z. Zwartek HZDR, Dresden, Germany
	The qual­ity of the pho­to­cath­odes is crit­i­cal for the sta-bil­ity and re­li­a­bil­ity of the pho­toin­jec­tor’s op­er­a­tion. Thanks to the ro­bust mag­ne­sium and Cs2Te pho­to­cath­odes, SRF gun-II at HZDR has been proven to be a suc-cess­ful ex­am­ple in CW mode for high cur­rent user op­er­a­tion. In this con­tri­bu­tion, we will pre­sent our ob­ser­va­tion of the QE evo­lu­tion of Cs2Te pho­to­cath­odes dur­ing SRF gun op­er­a­tion. The vari­ables in­clud­ing sub­strate sur­face, film thick­ness, Cs/Te sto­i­chio­met­ric, mul­ti­pact­ing, RF load­ing and charge ex­tract are con­sid­ered in the analy­sis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT022
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 06 July 2022
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THPOPT024	MIST - The MESA-Injector Source Two	2624
	M.A. Dehn, P.S. Plattner IKP, Mainz, Germany K. Aulenbacher HIM, Mainz, Germany K. Aulenbacher GSI, Darmstadt, Germany K. Aulenbacher KPH, Mainz, Germany
	Funding: Work supported by the German science ministry BMBF through Verbundforschung The new ac­cel­er­a­tor MESA (Mainz En­ergy Re­cov­er­ing Su­per­con­duct­ing Ac­cel­er­a­tor) will pro­vide an av­er­age CW elec­tron beam cur­rent of up to 10 mA. Op­er­at­ing at 1.3 GHz, this cor­re­sponds to a bunch charge of 7.7 pC. The new DC pho­toe­mis­sion source MIST is op­ti­mized for these re­quire­ments. A chal­lenge is heat­ing of the pho­to­cath­ode at high laser power. By a suit­able me­chan­i­cal con­struc­tion and the use of spe­cific ma­te­ri­als, the heat can be dis­si­pated dur­ing op­er­a­tion. Op­tions for fur­ther im­prove­ments are dis­cussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT024
About •	Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 01 July 2022
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THPOPT025	Photocathode Stress Test Bench at INFN LASA	2627
	D. Sertore, D. Giove, L. Monaco INFN/LASA, Segrate (MI), Italy A. Bacci, F. Canella, S. Cialdi, I. Drebot, D. Giannotti, L. Serafini INFN-Milano, Milano, Italy D. Cipriani, E. Suerra Università degli Studi di Milano, Milano, Italy G. Galzerano POLIMI, Milano, Italy G. Guerini Rocco Università degli Studi di Milano & INFN, Segrate, Italy
	A UHV test bench based on a 100 kV DC gun and a 100 MHz rep­e­ti­tion rate laser has been setup up at INFN LASA to test Cs2Te pho­to­cath­odes. This op­er­a­tion mode is the base­line of the BriXSinO pro­ject, cur­rently in the de­sign phase in our lab­o­ra­tory, and the qual­i­fi­ca­tion of the Cs2Te pho­to­cath­odes is a key issue. In this paper, we pre­sent the re­cent ad­vances in the dif­fer­ent as­pects of this R&D ac­tiv­ity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT025
About •	Received ※ 10 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022
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THPOPT026	Assembly and Characterization of Low-Energy Electron Transverse Momentum Measurement Device (TRAMM) at INFN LASA	2630
	D. Sertore, M. Bertucci, A. Bosotti, D. Giove, L. Monaco, R. Paparella INFN/LASA, Segrate (MI), Italy G. Guerini Rocco, C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	In the frame­work of high-bright­ness elec­tron beam gen­er­a­tion, ther­mal emit­tance is nowa­days a key pa­ra­me­ter. While al­kali tel­lurides are ex­ten­sively used in ad­vanced elec­tron sources, al­kali an­ti­monides pho­to­cath­odes demon­strated high QE in the vis­i­ble, thus mak­ing fea­si­ble CW op­er­a­tions for RF-based pho­toin­jec­tors. The INFN LASA lab­o­ra­tory in Milan is fully equipped with ded­i­cated pro­duc­tion sys­tems for pho­to­cath­ode prepa­ra­tion and op­ti­cal setup for QE eval­u­a­tion. In this paper, we de­scribe a newly de­signed de­vice ded­i­cated to elec­tron trans­verse mo­men­tum mea­sure­ment (TRAMM). It will be con­nected to the main pro­duc­tion cham­bers and will serve as an "emit­tance mon­i­tor­ing" sys­tem dur­ing pho­to­cath­ode growth. From the de­sign phase, through the pa­ra­me­ter es­ti­mate, as­sem­bly of the com­po­nents, to the in­stal­la­tion and first mea­sure­ments, we de­scribe the sta­tus of this pro­ject and its fu­ture de­vel­op­ments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT026
About •	Received ※ 09 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 07 July 2022
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THPOPT027	R&D on High QE Photocathodes at INFN LASA	2633
	D. Sertore, M. Bertucci, L. Monaco INFN/LASA, Segrate (MI), Italy G. Guerini Rocco Università degli Studi di Milano & INFN, Segrate, Italy S.K. Mohanty, H.J. Qian, F. Stephan DESY Zeuthen, Zeuthen, Germany
	We pre­sent the re­cent ac­tiv­i­ties on an­ti­monide and tel­luride al­kali based pho­to­cath­odes at INFN LASA. The R&D on Cs2Te ma­te­ri­als is fo­cused on in­ves­ti­gat­ing ef­fects of ma­te­r­ial thick­ness and growth pro­ce­dures on the pho­to­cath­odes per­for­mances dur­ing op­er­a­tion in RF guns. We aim to im­prove ther­mal emit­tance and long term sta­bil­ity of these films. The more re­cent work on al­kali an­ti­monide showed the need for sub­stan­tial im­prove­ments in sta­bil­ity and QE dur­ing op­er­a­tion. We pre­sent here our re­cent achieve­ments and plans for fu­ture ac­tiv­i­ties.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT027
About •	Received ※ 09 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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THPOPT028	Dependence of CsK2Sb Photocathode Performance on the Quality of Graphene Substrate Film	2637
	L. Guo, K. Goto, Y. Takashima Nagoya University, Nagoya, Japan H. Yamaguchi LANL, Los Alamos, New Mexico, USA M. Yamamoto KEK, Ibaraki, Japan
	Funding: U.S.-Japan Science and Technology Cooperation Program in High Energy Physics A pho­to­cath­ode that ex­tracts elec­trons by ir­ra­di­at­ing a semi­con­duc­tor or metal with a laser is ap­plied to ad­vanced ac­cel­er­a­tors and elec­tron mi­cro­scopes as a high-per­for­mance cath­ode. In par­tic­u­lar, the CsK2Sb pho­to­cath­ode is of in­ter­est be­cause it has fea­tures such as low emit­tance, ex­citabil­ity with vis­i­ble light, and high quan­tum ef­fi­ciency. Gen­er­ally, the CsK2Sb pho­to­cath­ode is pro­duced by de­posit­ing a cath­ode el­e­ment on a sub­strate, so that the cath­ode per­for­mance strongly de­pends on the sur­face con­di­tion of the sub­strate. We have found graphene as reusable sub­strate, which has the prop­erty of being chem­i­cally in­ac­tive. In this study, graphene film qual­ity de­pen­dence of CsK2Sb photo-cath­ode per­for­mance was eval­u­ated. Specif­i­cally, CsK2Sb cath­ode was de­posited using dif­fer­ent qual­ity graphene film sub­strates and their QE val­ues and uni­for­mity were com­pared. The qual­ity of graphene films was an­a­lyzed using X-ray Pho­to­elec­tron Spec­troscopy (XPS) and X-ray ab­sorp­tion spec­troscopy (XAS). We found that the graphene film can be cleaned by heat­ing at 500 deg. The QE of the cath­ode on a good qual­ity graphene film was higher and more uni­form than that on a poor qual­ity graphene film.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT028
About •	Received ※ 16 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 10 June 2022 — Issue date ※ 24 June 2022
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THPOPT029	Study on the Performance Improvement of Alkali Antimonide Photocathodes for Radio Frequency Electron Guns	2640
	R. Fukuoka, K. Ezawa, Y. Koshiba, M. Washio Waseda University, Tokyo, Japan K. Sakaue The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
	Semi­con­duc­tor pho­to­cath­odes such as Cs-Te and Cs-K-Sb are used as elec­tron sources in ac­cel­er­a­tors to gen­er­ate high bright­ness beams using radio fre­quency (rf) elec­tron guns. Al­kali an­ti­monide pho­to­cath­odes have a high quan­tum ef­fi­ciency (Q.E.) of ~10%, and their ex­ci­ta­tion wave­length is in the vis­i­ble light re­gion (532 nm), so that they are ex­pected to re­duce the re­quire­ments on the op­ti­cal sys­tem and in­crease the amount of charge com­pared to Cs-Te. How­ever, al­kali an­ti­monide pho­to­cath­odes have a short life­time and de­grade under poor vac­uum con­di­tions, so it is es­sen­tial to im­prove dura­bil­ity by pro­tec­tive film coat­ings. There­fore, we are cur­rently work­ing on the fab­ri­ca­tion of high Q.E. al­kali an­ti­monide pho­to­cath­odes that can with­stand the Q.E. re­duc­tion dur­ing coat­ing. In this pre­sen­ta­tion, we will re­port the re­sults of com­par­i­son be­tween the fab­ri­cated al­kali an­ti­monide pho­to­cath­ode and Cs-Te pho­to­cath­ode, and fu­ture prospects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT029
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022
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THPOPT030	Design Study of 30 MeV Linac for a Compact THz Radiation Source	2643
	S. Jummunt, S. Chunjarean, N. Juntong, S. Klinkhieo SLRI, Nakhon Ratchasima, Thailand K. Manasatitpong Synchrotron Light Research Institute (SLRI), Muang District, Thailand
	Funding: This work is supported by Science, Research, and Innovation Fund (SRI Fund) A com­pact THz ra­di­a­tion source plays a pos­si­bil­ity to achieve in­tense THz ra­di­a­tion at tun­able fre­quen­cies be­tween 0.5 and 5.0 THz, with a peak power of sev­eral MW and nar­row-band­width. This source re­quires es­sen­tially the re­li­able high gra­di­ent s-band lin­ear ac­cel­er­a­tor (linac) to pro­vide an elec­tron beam en­ergy up to 30 MeV with high bunch charge. In order to ob­tain a high gra­di­ent linac men­tioned, the cav­ity struc­ture has been op­ti­mized and per­formed using the soft­ware CST. The pre­lim­i­nary de­sign of linac and beam dy­nam­ics study are pre­sented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT030
About •	Received ※ 14 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 16 June 2022
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THPOPT033	Performance Characterisation at Daresbury Laboratory of Cs-Te Photocathodes Grown at CERN	2653
	L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C. Benjamin, H.M. Churn, L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C. Benjamin University of Warwick, Coventry, United Kingdom E. Chevallay, V.N. Fedosseev, E. Granados, M. Himmerlich, H. Panuganti CERN, Meyrin, Switzerland L.B. Jones, T.C.Q. Noakes, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: STFC Doctoral Training Studentship The search for high-per­for­mance pho­to­cath­odes is a pri­or­ity in the field of par­ti­cle ac­cel­er­a­tors. The sur­face char­ac­ter­is­tics of a pho­to­cath­ode af­fect many im­por­tant fac­tors of the pho­toe­mis­sion process in­clud­ing the pho­toe­mis­sion thresh­old, the in­trin­sic emit­tance and the quan­tum ef­fi­ciency. These fac­tors in turn de­fine the elec­tron beam qual­ity, which is mea­sur­able using fig­ures of merit like beam emit­tance, bright­ness and en­ergy spread. We pre­sent char­ac­ter­i­sa­tion mea­sure­ments for four cae­sium tel­luride pho­to­cath­odes syn­the­sized at CERN. The pho­to­cath­odes were trans­ported under ul­tra-high vac­uum (UHV) and analysed at STFC Dares­bury Lab­o­ra­tory, using ASTeC’s Mul­ti­probe (SAPI)* for sur­face char­ac­ter­i­sa­tion via XPS and STM, and for Mean Trans­verse En­ergy (MTE) mea­sure­ments using the Trans­verse En­ergy Spread Spec­trom­e­ter (TESS)**. The MTE mea­sure­ments were es­ti­mated at cryo­genic and room tem­per­a­tures based on the re­spec­tive trans­verse en­ergy dis­tri­b­u­tion curves. We dis­cuss cor­re­la­tions found be­tween the syn­the­sis pa­ra­me­ters, and the mea­sured sur­face char­ac­ter­is­tics and MTE val­ues. *B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017 **L.B. Jones et al., Proc. FEL ’13, TUPPS033, 290-293; https://accelconf.web.cern.ch/FEL2013/papers/tupso33.pdf
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT033
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 05 July 2022
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THPOPT034	Controlled Degradation of a Ag Photocathode by Exposure to Multiple Gases	2657
	L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom L.B. Jones, T.C.Q. Noakes, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: STFC Doctoral Training Studentship The search for high per­for­mance pho­to­cath­ode elec­tron sources is a pri­or­ity in the ac­cel­er­a­tor sci­ence com­mu­nity. The sur­face char­ac­ter­is­tics of a pho­to­cath­ode de­fine many im­por­tant fac­tors of the pho­toe­mis­sion process in­clud­ing the work func­tion, the in­trin­sic emit­tance and the quan­tum ef­fi­ciency of the pho­to­cath­ode. These fac­tors in turn de­fine the ul­ti­mate elec­tron beam qual­ity, which is mea­sur­able as nor­malised emit­tance, bright­ness and en­ergy spread. Strate­gies for im­prov­ing these pa­ra­me­ters vary, but un­der­stand­ing and in­flu­enc­ing the rel­e­vant cath­ode sur­face physics which un­der­pin these at­trib­utes is a pri­mary focus for the com­mu­nity*. We pre­sent per­for­mance data under il­lu­mi­na­tion at 266 nm for Ag (100) sin­gle-crys­tal cath­ode and a Ag poly­crys­talline cath­ode after pro­gres­sive ex­po­sure to O2, CO2, CO and N2 using our TESS** in­stru­ment both at room and cryo­genic tem­per­a­tures. Cru­cially the data shows the ef­fect of pro­gres­sive degra­da­tion*** in the pho­to­cath­ode per­for­mance as a con­se­quence of ex­po­sure to con­trolled lev­els of O2 and that ex­pos­ing an ox­i­dized Ag sur­face to CO can drive par­tial QE re­cov­ery. *K.L. Jensen; Appl. Phys. Lett. 89, 224103 (2006); **L.B. Jones et al.; Proc. FEL ’13, TUPPS033, 290-293; ***N. Chanlek et al.; J. Phys. D: Appl. Phys. (2014) 47, 055110;
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT034
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 10 July 2022
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THPOPT036	New Microwave Thermionic Electron Gun for APS Upgrade: Test Results and Operation Experience	2665
	S.V. Kutsaev, R.B. Agustsson, A.C. Araujo Martinez, R.D. Berry, O. Chimalpopoca, A.Y. Murokh, M. Ruelas, A.Yu. Smirnov, S.U. Thielk RadiaBeam, Santa Monica, California, USA J.E. Hoyt, W.G. Jansma, A. Nassiri, Y. Sun, G.J. Waldschmidt ANL, Lemont, Illinois, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Science, under contracts DE-SC0015191 and DE- AC02-06CH11357 Re­cently, Ra­di­a­Beam has de­signed and built a ro­bust thermionic RF gun with op­ti­mized elec­tro­mag­netic per-for­mance, im­proved ther­mal en­gi­neer­ing, and a ro­bust cath­ode mount­ing tech­nique. This gun al­lows to im­prove the per­for­mance of ex­ist­ing and fu­ture light sources, in­dus­trial ac­cel­er­a­tors, and elec­tron beam dri­ven te-ra­hertz sources. Un­like con­ven­tional elec­tri­cally or side-cou­pled RF guns, this new gun op­er­ates in ’-mode with the help of mag­netic cou­pling holes. Such a de­sign al-lows op­er­a­tion at longer pulses and has neg­li­gi­ble di­pole and quadru­pole com­po­nents. The gun pro­to­type was built, then in­stalled and tested at the Ad­vanced Pho­ton Source (APS) in­jec­tor. This paper pre­sents the re­sults of high power and beam tests of this RF gun, and op­er­a­tion-al ex­pe­ri­ence at APS to this mo­ment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT036
About •	Received ※ 31 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 27 June 2022
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THPOPT044	The Alkali-Metal Photocathode Preparation Facility at Daresbury Laboratory: First Caesium Telluride Deposition Results	2693
	H.M. Churn, C. Benjamin, L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C. Benjamin University of Warwick, Coventry, United Kingdom H.M. Churn, L.B. Jones, T.C.Q. Noakes Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Fourth gen­er­a­tion light sources re­quire high bright­ness elec­tron beams. To achieve this a pho­to­cath­ode with a high quan­tum ef­fi­ciency and low in­trin­sic emit­tance is re­quired, which is also ro­bust with a long op­er­a­tional life­time and low dark cur­rent. Al­kali-metal pho­to­cath­odes have the po­ten­tial to ful­fil these re­quire­ments, so are an im­por­tant re­search area for the ac­cel­er­a­tor physics com­mu­nity. STFC Dares­bury Lab­o­ra­tory are cur­rently com­mis­sion­ing the Al­kali-metal Pho­to­cath­ode Prepa­ra­tion Fa­cil­ity (APPF) which will be used to grow al­kali pho­to­cath­odes. Pho­to­cath­odes pro­duced by the APPF will be analysed using Dares­bury Lab­o­ra­tory’s ex­ist­ing Mul­ti­probe sys­tem* and the Trans­verse En­ergy Spread Spec­trom­e­ter (TESS)**. Mul­ti­probe can per­form a va­ri­ety of sur­face analy­sis tech­niques while the TESS can mea­sure the Mean Trans­verse En­ergy of a pho­to­cath­ode from its Trans­verse En­ergy Dis­tri­b­u­tion Curve over a large range of il­lu­mi­na­tion wave­lengths. We pre­sent an overview on our cur­rent progress in the com­mis­sion­ing and test­ing of the APPF, the re­sults from the first Cs-Te de­po­si­tion and de­tail the work planned to fa­cil­i­tate the man­u­fac­ture of Cs2Te pho­to­cath­odes for the CLARA ac­cel­er­a­tor***. *B.L. Militsyn, 4th EuCARD2 WP12.5 meeting, Warsaw, 14-15 Mar. 2017 **L. Jones et al., Proc. FEL ’13, TUPPS033, 290-293 ***D. Angal-Kalinin et al., Phys. Rev. Accel. Beams, Vol. 23, Iss. 4, 2020
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT044
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 23 June 2022
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THPOTK014	100 keV Electron Source Design for the New 3 GeV Synchrotron Facility in Thailand	2800
	N. Juntong, S. Bootiew, T. Chanwattana, Ch. Dhammatong, S. Jummunt, K. Kittimanapun, W. Phacheerak SLRI, Nakhon Ratchasima, Thailand K. Manasatitpong Synchrotron Light Research Institute (SLRI), Muang District, Thailand
	The Syn­chro­tron Light Re­search In­sti­tute (SLRI) is de­vel­op­ing a new syn­chro­tron light source with an elec­tron beam en­ergy of 3 GeV. The DC thermionic elec­tron gun was cho­sen be­cause it is sim­ple and less cost. The de­sign process is well known. The op­er­a­tion is more sta­ble com­pared to the RF gun. The cath­ode Y-646B was con­sid­ered be­cause it had al­ready been used at the old syn­chro­tron ma­chine and the pos­si­bil­ity of shar­ing the stock out­weighs other dis­ad­van­tages. More­over, it is used in many syn­chro­tron fa­cil­i­ties, so it is easy to find ref­er­ences. The pre­sent of the fo­cus­ing elec­trode was dis­cussed. The fo­cus­ing elec­trode will in­crease the com­plex­ity of the gun, but it is nec­es­sary to get a high-qual­ity beam from the gun. The de­signed elec­tron gun can pro­duce 1.1 A beams cur­rent with the nor­mal­ized emit­tance of 0.910 Pi·mm·mrad, which sat­is­fied the re­quire­ment of the linac in­jec­tor. The de­sign and study re­sults will be dis­cussed in this re­port.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK014
About •	Received ※ 20 May 2022 — Accepted ※ 14 June 2022 — Issue date ※ 29 June 2022
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