Effects of electron prebunching on the radiation growth rate of acollective (Raman) free-electron laser amplifier |
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Authors: | Leibovitch C Kongyi Xu Bekefi G |
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Affiliation: | Dept. of Phys., MIT, Cambridge, MA; |
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Abstract: | Experiments are reported on the effects of electron prebunching in a mildly relativistic, low-current (200-KV, 1-A) free-electron laser amplifier operating in the collective (Raman) regime at a frequency of ~10 GHz. Prebunching is established by injecting an electromagnetic wave into a bifilar helical wiggler and then transporting the bunched beam into a second magnetic wiggler region. The wave growth rate is deduced from measurements of the radiation intensity as a function of interaction length. Observations show that prebunching can increase the radiation growth rate manyfold as compared with a system without prebunching. Studies are presented both in the small-signal (linear) regime, and in the nonlinear (saturated) regime |
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