CONSIDERATIONS FOR DOUBLE PULSE LASING FROM THE BESSY-FEL∗

BESSY proposes a linac-based High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) facility with three independent FEL lines [1]. High efficiency of the FEL process is ensured as the seed radiation interacts only with unperturbed parts of the electron bunch in ev-ery HGHG-stage. However, simulations show that bunch parts that have previously lased generate a noticeable ra-diation power level in the final amplifiers. This motivated simulation studies on the significance and intensity of such inherent additional pulses. It is revealed that the BESSY-FEL provides the opportunity to deliver multiple pulses at the FEL exit with peak powers in the MW- as well as dou-ble pulses in the GW-range. This might be of high interest to the user community