02 Light Sources
T02 - Electron Sources and Injectors

Paper	Title	Page
TUPMA07	Future Upgrades of the NSLS-II Injector	601
	T.V. Shaftan, R.P. Fliller, R. Heese, J. Rose, G.M. Wang, F.J. Willeke BNL, Upton, Long Island, New York, USA
	In 2013 the NSLS-II in­jec­tor, which con­sists of 200 MeV linac, 3 GeV booster, trans­port lines and stor­age ring in­jec­tion straight sec­tion, will be en­ter­ing op­er­a­tions. While build­ing the NSLS-II in­jec­tion sys­tem we in­vested sub­stan­tial ef­forts in de­vel­op­ing and pre­serv­ing op­tions for fu­ture up­grades and en­chance­ments. In this paper we dis­cuss the po­ten­tial of in­cre­men­tal evo­lu­tion of the NSLS-II in­jec­tor per­for­mance by en­abling up­grade op­tions, such as the sec­ond gun, flex­i­ble bunch pat­terns, beam stack­ing in the booster, emit­tance com­pen­sa­tion tech­niques in the trans­port lines, etc. These up­grades will ex­pand ca­pa­bilites of the NSLS-II fa­cil­ity and in­crease op­er­a­tional re­li­a­bil­ity.
TUPMA09	Analysis and Optimization of Coupler Kick in APEX	607
	H.J. Qian, S. Kwiatkowski, C. F. Papadopoulos, Z. Paret, F. Sannibale, J.W. Staples, R.P. Wells LBNL, Berkeley, California, USA
	A high rep­e­ti­tion rate (~MHz) and high bright­ness pho­toin­jec­tor, based on VHF band CW nor­mal con­duct­ing (NC) RF gun, is being de­vel­oped under Ad­vanced Pho­toin­jec­tor EX­per­i­ment (APEX) at Lawrence Berke­ley Lab. A NC 30 MeV L-band linac sys­tem will be added after the gun to demon­strate beam bright­ness with lower rep­e­ti­tion rate (~10 Hz). In this paper, cou­pler kicks from APEX buncher and ac­cel­er­a­tion cav­i­ties are eval­u­ated by 3D RF sim­u­la­tion, an­a­lyt­i­cal model and beam track­ing, and cou­pler cells are op­ti­mized to min­i­mize emit­tance di­lu­tion due to cou­pler kicks.
TUPMA10	LLNL X-band Test Station Status	610
	R.A. Marsh, F. Albert, G.G. Anderson, S.G. Anderson, C.P.J. Barty, E.T. Dayton, S.E. Fisher, D.J. Gibson, F.V. Hartemann, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. An X-band test sta­tion is being built at LLNL to sup­port in­verse Comp­ton-scat­ter­ing x-ray and gamma-ray source de­vel­op­ment. The major com­po­nents for the X-band test sta­tion have been de­signed, fab­ri­cated, in­stalled, and aligned. The XL-4 kly­stron has been de­liv­ered, dressed and in­stalled in the Scan­di­Nova mod­u­la­tor, and tested to full peak power. Final as­sem­bly and bake­out of RF trans­port, test sta­tion sup­ports, and ac­cel­er­a­tor com­po­nents is com­plete, and the cur­rent sta­tus of com­mis­sion­ing and first beam will be pre­sented and dis­cussed. Fu­ture up­grade paths and con­fig­u­ra­tion for a va­ri­ety of x-ray and gamma-ray ap­pli­ca­tions will be dis­cussed along with sched­ule for planned ex­per­i­ments.
TUPMA15	Monte Carlo Simulations of Charge Transport and Electron Emission from GaAs Photocathodes	616
	Y. Choi, D.A. Dimitrov, C. Nieter Tech-X, Boulder, Colorado, USA I.V. Bazarov, S.S. Karkare Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under SBIR grant DE-SC0006246 and Early Career DE-SC0003965. The need for a bright elec­tron beam is in­creas­ing in the fields of x-ray sci­ence, elec­tron dif­frac­tion and elec­tron mi­croscopy which are re­quired for col­lid­ers. GaAs-based pho­to­cath­odes have the po­ten­tial to pro­duce high-bright­ness, un­po­lar­ized and po­lar­ized, elec­tron beams with per­for­mance that meets mod­ern col­lider re­quire­ments. Even after decades of in­ves­ti­ga­tion, how­ever, the exact mech­a­nism of elec­tron emis­sion from GaAs is not well un­der­stood. There­fore, we in­ves­ti­gate pho­toe­mis­sion from a GaAs pho­to­cath­ode using de­tailed Monte Carlo elec­tron trans­port sim­u­la­tions. In­stead of a sim­ple step­wise po­ten­tial, we con­sider a tri­an­gu­lar bar­rier in­clud­ing the ef­fect of the image charge to take into ac­count the ef­fect of the ap­plied field on the emis­sion prob­a­bil­ity. The sim­u­la­tion re­sults are com­pared with the ex­per­i­men­tal re­sults for quan­tum efficiency, an­gu­lar and en­ergy dis­tri­b­u­tions of emit­ted elec­trons with­out the as­sump­tion of any ad hoc pa­ra­me­ters.
TUPMA19	Wisconsin SRF Electron Gun Commissioning	622
	J. Bisognano, M.J. Bissen, R.A. Bosch, M.Y. Efremov, D. Eisert, M.V. Fisher, M.A. Green, K. Jacobs, R.G. Keil, K.J. Kleman, G.C. Rogers, M.C. Severson, D. Yavuz UW-Madison/SRC, Madison, Wisconsin, USA R. Bachimanchi, C. Hovater, R.A. Legg, T. E. Plawski, T. Powers JLAB, Newport News, Virginia, USA
	Funding: Work supported by DOE Award #DE-SC0005264 and the University of Wisconsin The Uni­ver­sity of Wis­con­sin has com­pleted fab­ri­ca­tion and com­mis­sion­ing of a low fre­quency (199.6 MHz) su­per­con­duct­ing elec­tron gun based on a quar­ter wave res­onator (QWR) cav­ity. Its con­cept was op­ti­mized to be the source for a CW free elec­tron laser fa­cil­ity. The gun de­sign in­cludes ac­tive tun­ing and a high tem­per­a­ture su­per­con­duct­ing so­le­noid. We will re­port on the sta­tus of the Wis­con­sin SRF elec­tron gun pro­gram, in­clud­ing com­mis­sion­ing ex­pe­ri­ence and first beam mea­sure­ments.
TUPMA20	Effect of RF Gradient upon the Performance of the Wisconsin SRF Electron Gun	625
	R.A. Bosch UW-Madison/SRC, Madison, Wisconsin, USA R.A. Legg JLAB, Newport News, Virginia, USA
	The per­for­mance of the Wis­con­sin 200-MHz SRF elec­tron gun is sim­u­lated for sev­eral val­ues of the RF gra­di­ent. Bunches with charge of 200 pC are mod­eled for the case where emit­tance com­pen­sa­tion is com­pleted dur­ing post-ac­cel­er­a­tion to 85 MeV in a TESLA mod­ule. We first per­form sim­u­la­tions in which the ini­tial bunch ra­dius is op­ti­mal for the de­sign gra­di­ent of 41 MV/m. We then op­ti­mize the ra­dius as a func­tion of RF gra­di­ent to im­prove the per­for­mance for low gra­di­ents.
WEOAA4	Low Emittance in the Cornell ERL Injector Prototype	706
	C.M. Gulliford, A.C. Bartnik, I.V. Bazarov, B.M. Dunham Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by National Science Foundation (Grant No. DMR-0807731) We pre­sent a de­tailed study of the emit­tances pro­duced in the Cor­nell En­ergy Re­cov­ery Linac Pho­toin­jec­tor. Both the hor­i­zon­tal and ver­ti­cal trans­verse phase spaces, as well as the time-re­solved (sliced) hor­i­zon­tal phase space, were sim­u­lated and di­rectly mea­sured at the end of the in­jec­tor for 19 pC and 77 pC bunches at roughly 8 MeV. The re­sult­ing 90% nor­mal­ized trans­verse emit­tances for 19 (77) pC/bunch were 0.23 ± 0.02 (0.51 ± 0.04) μm in the hor­i­zon­tal plane, and 0.14 ± 0.01 (0.29 ± 0.02) μm in the ver­ti­cal plane, re­spec­tively. These emit­tances were mea­sured with a cor­re­spond­ing bunch length of 2.1±0.1 (3.0±0.2) ps, re­spec­tively. For both bunch charges, the rms mo­men­tum spread was de­ter­mined to be on the order of 10-3. Ex­cel­lent over­all agree­ment be­tween mea­sure­ment and sim­u­la­tion has been demon­strated. The beam bright­ness mea­sured in this work is sig­nif­i­cantly bet­ter than the best of mod­ern stor­age rings, and rep­re­sents a mile­stone for the field of high-bright­ness, high-cur­rent pho­toin­jec­tors.
	Slides WEOAA4 [7.284 MB]