Analysis of FEL radiation in pulsed raman regime

Summary

A direct numerical analysis, based on the Lienard-Wiechert potentials, is performed in the present paper, aiming to describe the relativistic interaction of the electrons composing a high-intensity beam (in Raman regime) both with each other and with the fields of an FEL structure and of an external resonant travelling electromagnetic wave. The different accelerations, due to the various forces acting on the charged particles, are seen to give different contributions to the total radiation field, which are separately considered here. The angular and frequency distributions of the obtained radiation are compared with the analytic ones deduced in the particular case of a single charge launched along the FEL structure. The interference effect between the fields of many bunches is seen to cause the shrinkage of the resulting radiation beam.