Generalized non-reflecting radiation boundary conditions: Numerical implementation

A numerical procedure to implement non-reflecting radiation boundary conditions, based on the Laplace Transform, is described in details and tested successfully on a simple two frequencies test problem. The method is then implemented in the time-dependent gyrotron simulation code TWANG. In the case for which the code exhibits a multi-frequency spectrum with the same transverse mode, it is shown that the reflection of these frequencies at the radiating boundary can be effectively suppressed by this method.