ABSTRACT
An amplitude and phase compensation system has been developed and tested at the University of Hawai'i for the optimization of the RF drive system to the Mark V free-electron laser. Temporal uniformity of the RF drive is essential to the generation of an electron beam suitable for optimal free-electron laser performance and the operation of an inverse Compton scattering x-ray source. The design of the RF measurement and compensation system is described in detail and the results of RF phase compensation are presented. Performance of the free-electron laser was evaluated by comparing the measured effects of phase compensation with the results of a computer simulation. Finally, preliminary results are presented for the effects of amplitude compensation on the performance of the complete system.
ABSTRACT
The design and application of an uncoated sapphire plate that acts as both the beam splitter and the output coupler of an interferometric laser resonator are described. Output coupling is provided at one of the surfaces by p-polarized (TM) reflection near the Brewster angle, and axial-mode selection is enforced at the other surface by s-polarized (TE) reflection at the same angle of incidence. The design is discussed in the context of the phase-locked, rf linac free-electron laser, in which the coupling of adjacent optical pulses at the beam splitter induces temporal phase coherence among all the pulses in the output beam; this coherence is manifested in the frequency domain as a reduction in the number of axial modes per rf frequency interval. The Michelson and Fox-Smith resonator designs are compared, and applications to cavity dumping are discussed.
