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Title: Optical gain, phase shift, and profile in free-electron lasers. Interim report

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 have 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 are 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.

Authors:
; ;
Publication Date:
Research Org.:
Naval Research Lab., Washington, DC (USA)
OSTI Identifier:
6088735
Report Number(s):
AD-A-183072/8/XAB; NRL-MR-5998
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; AMPLIFIERS; FREE ELECTRON LASERS; OPTICAL PROPERTIES; DENSITY; DISPERSIONS; DISTRIBUTION; ELECTRON BEAMS; GAIN; NUMERICAL ANALYSIS; PHASE SHIFT; AMPLIFICATION; BEAMS; ELECTRONIC EQUIPMENT; EQUIPMENT; LASERS; LEPTON BEAMS; MATHEMATICS; PARTICLE BEAMS; PHYSICAL PROPERTIES; 420300* - Engineering- Lasers- (-1989); 420800 - Engineering- Electronic Circuits & Devices- (-1989)

Citation Formats

Hafizi, B, Sprangle, P A, and Ting, A. Optical gain, phase shift, and profile in free-electron lasers. Interim report. United States: N. p., 1987. Web.
Hafizi, B, Sprangle, P A, & Ting, A. Optical gain, phase shift, and profile in free-electron lasers. Interim report. United States.
Hafizi, B, Sprangle, P A, and Ting, A. Mon . "Optical gain, phase shift, and profile in free-electron lasers. Interim report". United States.
@article{osti_6088735,
title = {Optical gain, phase shift, and profile in free-electron lasers. Interim report},
author = {Hafizi, B and Sprangle, P A and Ting, A},
abstractNote = {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 have 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 are 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {7}
}

Technical Report:
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