Simulation of high gain high harmonics oscillator with optical klystron free electron laser

A possibility of new structure for high harmonics high gain (HGHG) free electron laser is proposed, in which the structure of the optical klystron is placed in the resonance cavity to form the HGHG modulator. This particular modulator can remove seed laser of the conventional HGHG. Such a scheme will be beneficial to high-repetition-rate, full coherence and narrow bandwidth. Detail simulation by GINGER was given, showing that up to 12 harmonics the output of the oscillator is still very well.