Small signal gain based on analytic models of thin intense electron beams
We develop the free-electron laser theory of the effective energy distribution and the small signal gain for a thin electron beam. The assumption of thinness allows us to treat various transverse locations and electron beam trajectory angles as introducing phase shifts that have the same effect as those introduced by a change in energy of the electron. We have extended these ideas in five important ways. The first is the ability to treat electron beams with three different classes of matching or symmetry conditions: (1) electron beams with separate betatron matching in each plane, (2) those with aspect ratio matching, and (3) crossed matched beams. Manifestations of these symmetries include elliptical cross sections and electron beams that have modulated spatial profiles. Second, two emittance parameters for the electron beam are shown to consolidate into a single parameter that describes most of the energy variation of the effective energy distributions. Third, these calculations extend to energy distributions, angular distributions, and spatial distributions that all follow gaussian profiles. Fourth, this model incorporates the description of the incident gaussian optical beam and the above electron beam dynamics into a single influence function kernal. Fifth, three-dimensional profiles of the optical fields are computed. In this work the parameters of the incident optical beam are included. The resulting transverse dependence of the fields may be characterized by an optical beam radius. This optical beam width starts out large compared to the thin electron beam and then, in the example given, contracts to a size that becomes so small that the thin beam assumption is violated. 10 refs., 5 figs.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOD
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6362135
- Report Number(s):
- LA-UR-90-3595; CONF-9009166-9; ON: DE91001874
- Resource Relation:
- Conference: 12. international free electron laser conference (FEL-12), Paris (France), 17-21 Sep 1990
- Country of Publication:
- United States
- Language:
- English
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MATHEMATICAL MODELS
ANALYTICAL SOLUTION
ASPECT RATIO
BEAM BUNCHING
BEAM DYNAMICS
BEAM EMITTANCE
BEAM OPTICS
BETATRONS
DIFFRACTION
ENERGY SPECTRA
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AMPLIFICATION
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COHERENT SCATTERING
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