Theoretical study of power relativistic amplifiers for electron beam bunching

The modern approach to an injector of the Two Beam Accelerator driver is based on bunched electron beam using. The simulation results and comparison of the bunching of a relativistic electron beam produced by a free electron (FEL) and by a travelling-wave tube (TWT) at the low energy region of electron beams are under discussion. With the help of a rather simple model it is shown that the electron beam bunching in the TWT occurs at a shorter length as compared with the FEL according to the well known fact that the space gain in the TWT is higher than in the FEL at low electron energies. The comparison of the simulation and experimental results on the FEL bunching are presented too