The wakefields due to the rough surface of the vacuum chamber have a major influence on the beam
dynamics in future Linear Colliders and Linac based Free Electron Lasers. Some different models are
developed to predict its effect, however, rather different predictions are presented with these models.
An experiment to characterize the effects of the surface roughness is designed and carried out at
Brookhaven Accelerator Test Facility (ATF) in order to test these models. It is experimentally
demonstrated that the surface roughness wakefield induced energy spread can be predicted well by
the model of pure inductive impedance combined with the low-frequency resonator mode.
Measurements for the energy loss are agreed well with the expectations by the resonator mode.The
National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL) is considering
an upgrade based on the Photoinjected Energy Recovering Linac (PERL). The various injector
schemes for this machine are being extensively investigated at BNL. One of the possible options is
photocathode DC gun. The schematic layout of a PERL DC gun based injector and its preliminary
beam dynamics are presented in this paper. The transverse and longitudinal emittance of
photo-electron beam were optimized for a DC field 500 kV.
Talk Slides:
part 1,
part 2
(Coffee & Cookies before the seminar starting 10:00 am)