TESLA: simulation code for multiple beam klystrons

TESLA (Telegraphist's Equations Solution Linear beam Amplifiers) is a new code designed to simulate linear beam vacuum electronic devices with cavities, such as klystrons, interaction klystrons, twistrons, and coupled cavity amplifiers. The model includes a self-consistent, nonlinear solution of the three-dimensional electron equations of motion and the solution of time-dependent field equations. Also, fields in the external cavities are modeled with circuit like equations and couple to fields in the beam region through boundary conditions on the beam tunnel wall.