• J. Musson, J. M. Grames, J. Hansknecht, R. Kazimi, M. Poelker
  Jefferson Lab, Newport News, Virginia

Recent upgrades to the CEBAF Polarized Source include a fiber-based seed laser, capable of producing pulses with frequency centered at 499 MHz. Combined with the existing three-beam Chopper, an aliasing, or beat frequency technique is used to produce long time intervals between individual electron microbunches (tens of nanoseconds) by merely varying the nominal 499 MHz drive laser frequency by <20%. This RF Laser modulator uses a divider and heterodyne scheme to maintain coherence with the accelerator Master Oscillator, while providing delay resolution in increments of 2ns. Laser repetition frequencies producing bunch repetition rates between 20 MHz and 100 MHz are demonstrated, resulting in time delays between 50 and 10 ns, respectively. Also, possible uses for such a beam are discussed as well as intended development. Authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177