Multimode nonlinear analysis of free-electron laser amplifiers in three dimensions
The nonlinear evolution of a free-electron laser (FEL) amplifier is investigated for a configuration in which an electron beam propagates through an overmoded rectangular waveguide in the presence of a planar wiggler with parabolically tapered pole pieces. The analysis is fully three dimensional and describes the evolution of an arbitrary number of resonant TE and/or TM modes of the rectangular guide as well as the trajectories of an ensemble of electrons. Numerical simulations are conducted for parameters consistent with the 35-GHz amplifier experiment performed by Orzechowski and co-workers (Phys. Rev. Lett. 54, 889 (1985); 57, 2172 (1986)), in which the TE/sub 01/, TE/sub 21/, and TM/sub 21/ modes were observed. The theory is found to be in good agreement with the experiment. Surprisingly, comparison with a single-mode analysis shows that the enhancement of the efficiency of the TE/sub 01/ mode obtained by means of a tapered wiggler is significantly greater (as well as being in substantial agreement with the experiment) when the TE/sub 21/ and TM/sub 21/ modes are included in the simulation.
- Research Organization:
- Science Applications International Corporation, McLean, Virginia 22102
- OSTI ID:
- 5276254
- Journal Information:
- Phys. Rev. A; (United States), Vol. 37:9
- Country of Publication:
- United States
- Language:
- English
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