H.K. Avetissian, T. R. Hovhannisyan, G.F. Mkrtchian
Plasma Physics Laboratory, Department of Theoretical Physics
In the more conventional undulator devices of FEL to achieve X-ray domain one should increase the electron's energies up to several Gev. On the other hand at such energies the gain is rather small because of sharp dependence on energy of electrons. One of the possible ways to increase the efficiency of X-ray FEL is the quantum regime of generation excluding the inverse process of absorption. For the latter the characteristic spread of electron beam should be much less than the recoil energy, which is problematic for the undulator as well as for other schemes.
In this work the scheme of X-ray coherent radiation generation in nonlinear quantum regime by means of mildly relativistic high density electron beams and strong pump laser field is investigated. The latter makes possible to achieve quantum regime of generation at high harmonics of Doppler-shifted pump frequencies, which is possible due to recent achievements in high power laser technology.
The consideration is based on the self-consistent set of the Maxwell-Dirac equations. Because of nonequdistantness of the energy-momentum levels the probe wave resonantly couples only two Volkov states and the coupled equations are solved in the slow varying envelope approximation.
