Author: Welch, J.J.
Paper Title Page
TUAL2 Commissioning the New LCLS X-band Transverse Deflecting Cavity with Femtosecond Resolution 308
 
  • P. Krejcik, F.-J. Decker, Y. Ding, J.C. Frisch, Z. Huang, J.R. Lewandowski, H. Loos, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch
    SLAC, Menlo Park, California, USA
  • C. Behrens
    DESY, Hamburg, Germany
  
  Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515
The new X-band trans­verse de­flect­ing cav­ity began op­er­a­tion in May 2013 and is in­stalled down­stream of the LCLS un­du­la­tor. It is op­er­ated at the full 120 Hz beam rate with­out in­ter­fer­ing with the nor­mal FEL op­er­a­tion for the pho­ton users. The de­flected beam is ob­served on the elec­tron beam dump pro­file mon­i­tor, which acts as an en­ergy spec­trom­e­ter in the ver­ti­cal plane. We ob­serve, on a pulse by pulse basis, the time re­solved en­ergy pro­file of the spent elec­tron beam from the un­du­la­tor. The struc­ture is pow­ered from a 50 MW X-band kly­stron, giv­ing a 48 MV kick to the beam which yields a 1 fs rms time res­o­lu­tion on the screen. We have mea­sured the lon­gi­tu­di­nal pro­file of the elec­tron bunches both with the FEL op­er­at­ing and with the las­ing sup­pressed, al­low­ing re­con­struc­tion of both the lon­gi­tu­di­nal pro­file of the in­com­ing elec­tron beam and the time-re­solved pro­file of the X-ray pulse gen­er­ated in the FEL. We are im­me­di­ately able to see whether the bunch is chirped and which parts of the bunch are las­ing, giv­ing us new in­sight into tun­ing the ma­chine for peak per­for­mance. The per­for­mance of the sys­tem will be pre­sented along with ex­am­ples of mea­sure­ments taken dur­ing LCLS op­er­a­tion. 		 
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