Accession Number : ADA183072

Title :   Optical Gain, Phase Shift and Profile in Free-Electron Lasers.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Hafizi,B ; Sprangle,Phillip A ; Ting,A

PDF Url : ADA183072

Report Date : 20 Jul 1987

Pagination or Media Count : 49

Abstract : The gain, phase shift, wavefront curvature and radius of the radiation envelope in a free electron laser amplifier are obtained in the small signal regime. The electron beam is assumed to have a Gaussian density distribution in the transverse direction. Numerical calculations indicate that the radius and curvature of the radiation beam entering a wiggler asymptote to unique, spatially constant values after a finite transition region. However, in the asymptotic region the wavefronts are divergent. Analytical expressions for the gain, phase shift, curvature and spot size and derived. It is shown analytically that small perturbations of the optical waist and curvature about the matched value are spatially damped out, indicating the stability of the matched envelope. When the electron beam envelope is modulated in space, the optical spot size oscillates with an almost identical wavelength but is delayed in phase. In the case of small amplitude long wavelength betatron modulation of the electron beam envelope, generation of optical sidebands in wave number space is examined and the effect on the dispersions characteristics of the primary wave is found to be negligible for typical experimental parameters.

Descriptors :   *FREE ELECTRON LASERS, *LASER AMPLIFIERS, MATHEMATICAL ANALYSIS, DENSITY, DISTRIBUTION, ELECTRON BEAMS, TRANSITIONS, MATCHING, GAIN, CONSTANTS, DISPERSIONS, ENVELOPE(SPACE), MATCHING, COMPUTATIONS, NUMERICAL ANALYSIS, OPTICAL PROPERTIES, LASER SPOTS, SIZES(DIMENSIONS), RADIATION, TRANSVERSE, PHASE SHIFT, PERTURBATIONS, CURVATURE, WAVEFRONTS

Subject Categories : Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE