Electron dynamics in a free electron laser with a reversed axial guide field

In order to interpret the experiment of Conde and Bekefi, electron trajectories are studied for a configuration with a reversed axial guide field. In the vicinity of ‘‘antiresonance,’’ electrons are shown to have chaotic trajectories when emitted far enough from the axis. Thus, the interaction effic...

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Bibliographic Details
Published in:Journal of applied physics 1996-05, Vol.79 (9), p.6722-6728
Main Authors: Bourdier, A., Gardent, D.
Format: Article
Language:English
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Summary:In order to interpret the experiment of Conde and Bekefi, electron trajectories are studied for a configuration with a reversed axial guide field. In the vicinity of ‘‘antiresonance,’’ electrons are shown to have chaotic trajectories when emitted far enough from the axis. Thus, the interaction efficiency is degraded for most particles. This explains the large dip in radiative power observed and predicted by different simulation codes. The very good efficiency observed in the experiment is explained by a compromise between a high amplitude perpendicular velocity and a regular enough axial momentum for the electrons. It is also explained by the fact that when photons are emitted, the axial kinetic energy is not too much affected. A new situation for which a small peak in efficiency should be observed is predicted.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.361492