Numerical simulation of the dynamic processes in the gyrotron adiabatic trap

Abstract

The output parameters of CW and quasi-CW gyrotrons are to a considerable extent defined by the quality of helical electron beams (HEBs) produced by magnetron-injection guns (MIGs). The characteristic feature of MIGs is the trapped magnetic field distribution and therefore some of electrons with greatest oscillatory velocities are reflected from the magnetic mirror and then are locked into the adiabatic trap between the cathode and cavity. According to the recent experimental data trapped electrons render the essential influence upon beam parameters that in particular causes the necessity to reduce the share of the oscillatory energy t/sub /spl perp// in the beam for conservation of its stability. Decreasing of t/sub /spl perp// leads to reducing the output gyrotrons efficiency. These facts denote necessity further perfection of the theoretical model of HEB first of all by taking into account the electrons reflected from the magnetic mirror. In this paper the results of numerical simulation of relaxation processes in MIGs working in subcritical regime and forming regularly intersecting, boundary and quasilaminar beams are presented.