Author: Wells, R.P.
Paper Title Page
TUA01
 APEX: A Photo-injector for High Average Power Light Sources and Beyond  
 
  • D. Filippetto, C.W. Cork, S. De Santis, L.R. Doolittle, G. Huang, R. Huang, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, F. Sannibale, J.W. Staples, R.P. Wells
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Di­rect ob­ser­va­tion of struc­tural dy­nam­ics in com­plex sys­tems calls for a new gen­er­a­tion of ul­tra­fast in­stru­ments with en­hanced av­er­age bright­ness and in­creased sta­bil­ity. The APEX elec­tron source at LBNL was con­ceived and built for an­swer­ing that de­mand. It com­bines ul­tra-short bunches and high ac­cel­er­at­ing fields of rf guns, with high-rep­e­ti­tion-rate, sta­bil­ity and re­li­a­bil­ity typ­i­cal of CW sources. The suc­cess­ful demon­stra­tion of the source key per­for­mances, such as ac­cel­er­at­ing field, emit­tance and beam cur­rent, would en­able high rep­e­ti­tion rate op­er­a­tions for ap­pli­ca­tions such as X-Ray FELs, and ul­tra­fast elec­tron dif­frac­tion. We pre­sent the lat­est re­sults, in­clud­ing cath­ode tests, photo-beam and dark cur­rent char­ac­ter­i­za­tion, laser and beam jit­ter re­sults, and fu­ture plans. 		 
slides icon Slides TUA01 [18.646 MB]  
 
THP042 The LCLS-II Injector Design 815
 
  • J.F. Schmerge, A. Brachmann, D. Dowell, A.R. Fry, R.K. Li, Z. Li, T.O. Raubenheimer, T. Vecchione, F. Zhou
    SLAC, Menlo Park, California, USA
  • A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Filippetto, R. Huang, C. F. Papadopoulos, G.J. Portmann, J. Qiang, F. Sannibale, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
  • A. Lunin, N. Solyak, A. Vivoli
    Fermilab, Batavia, Illinois, USA
  
  The new LCLS-II pro­ject will con­struct a 4 GeV con­tin­u­ous wave (CW) su­per­con­duct­ing lin­ear ac­cel­er­a­tor to si­mul­ta­ne­ously feed two un­du­la­tors which will cover the spec­tral ranges 0.2-1.2 keV and 1-5 keV, re­spec­tively. The in­jec­tor must pro­vide up to 300 pC/bunch with a nor­mal­ized emit­tance < 0.6 mm and peak cur­rent > 30 A at up to 1 MHz rep­e­ti­tion rate. An elec­tron gun with the re­quired bright­ness at such high rep­e­ti­tion rate has not yet been demon­strated. How­ever, sev­eral dif­fer­ent op­tions have been ex­plored with re­sults that meet or ex­ceed the per­for­mance re­quire­ments of LCLS-II. The avail­able tech­nolo­gies for high rep­e­ti­tion-rate guns, and the need to keep dark cur­rent within ac­cept­able val­ues, limit the ac­cel­er­at­ing gra­di­ent in the elec­tron gun. We pro­pose a CW nor­mal con­duct­ing low fre­quency RF gun for the elec­tron source due to a com­bi­na­tion of the sim­plic­ity of op­er­a­tion and the high­est achieved gra­di­ent in a CW gun, po­ten­tially al­low­ing for lower beam emit­tances. The high gra­di­ent is es­pe­cially sig­nif­i­cant at the 300 pC/bunch charge where beam qual­ity can suf­fer due to space charge. This paper de­scribes the de­sign chal­lenges and pre­sents our so­lu­tions for the LCLS-II in­jec­tor.  
 
THP057 Longitudinal and Transverse Optimization for a High Repetition Rate Injector 864
 
  • C. F. Papadopoulos, D. Filippetto, R. Huang, G.J. Portmann, H.J. Qian, F. Sannibale, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
  • A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A. Brachmann, D. Dowell, P. Emma, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou
    SLAC, Menlo Park, California, USA
  • A. Vivoli
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The in­jec­tor is the low en­ergy part of a linac, where space charge and kine­matic ef­fects may af­fect the elec­tron beam qual­ity sig­nif­i­cantly, and in the case of sin­gle pass sys­tems de­ter­mines the bright­ness in the down­stream com­po­nents. Fol­low­ing the in­creas­ing de­mand for high rep­e­ti­tion rate user fa­cil­i­ties, the VHF-gun, a nor­mal con­duct­ing, high rep­e­ti­tion rate (1 MHz) RF gun op­er­at­ing at 186 MHz has been con­structed at LBNL within the APEX pro­ject and is under op­er­a­tion. In the cur­rent paper, we re­port on the sta­tus of the beam dy­nam­ics stud­ies. For this, a multi-ob­jected ap­proach is used, where both the trans­verse and the lon­gi­tu­di­nal phase space qual­ity is op­ti­mized, as quan­ti­fied by the trans­verse emit­tance and the bunch length and en­ergy spread re­spec­tively. We also re­port on dif­fer­ent bunch charge op­er­at­ing modes.