Cavity length adjustment and output FEL intensity optimization

The authors reconsider in more quantitative detail the possibility of enhancing the output intensity of a free electron laser (FEL) oscillator operating with bunched electron beam and finite macropulse duration, adjusting the cavity length while the signal grows. In a forthcoming publication G. Dattoli et al. point out that the output power can be enhanced by moving the cavity mirrors while the intercavity signal grows in such a way that the system is operating at the value of the cavity length providing the maximum gain. Practical solutions to realize the mirror movements are also discussed. The authors complete the analysis to be published by presenting simple formulas which allow a straightforward evaluation of the power enhancement.<
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