MAGY: A time-dependent code for simulation of slow and fast microwave sources

We present the newly developed Maryland Gyrotron (MAGY) code for modeling of slow and fast microwave sources. The code includes a time-dependent description of the electromagnetic fields and a self-consistent analysis of the electrons. The calculations of the electromagnetic fields are based on the waveguide modal representation, which allows the solution of a relatively small number of coupled one-dimensional partial differential equations for the amplitudes of the modes, instead of the full solution of Maxwell's equations. Moreover, the basic time scale for updating the electromagnetic fields is the cavity fill time and not the high frequency of the fields. The equations of motion of the electrons are formulated within the framework of the guiding-center approximation and solved with the electromagnetic fields as the driving forces. Therefore, at each time step, a set of trajectories are calculated and used as current sources for the fields. We present two examples for the operation of the code, namely the two-cavity gyroklystron and the backward-wave oscillator (BWO), These examples demonstrate the possible usage of the code for a wide variety of electron-beam systems.