Efficiency of energy recovery multistage systems in gyrotrons

The efficiency estimates of multistage electron energy recovery systems are important for gyrotrons operated at the first and second cyclotron harmonics. The development of multistage energy recovery systems requires knowledge of the electron energy spectra F(W) after the interaction with RF field. In this paper the numerical calculation of F(W) was carried out by the method of big particles on the basis of theory of gyrotron with non-fixed RF field structure taking into account the electron oscillatory velocity spread. Gaussian function of oscillatory velocity distribution at the working space entrance was used