Three Dimensional Klystron Simulation

The development ofhigh power klystrons requires computer codes simulating the complex interaction of electrons with the electromagnetic field as realistically as possible. We present a three dimensional computer simulation of a klystron output circuit including fully relativistic particle dynamics. The power extraction is simulated with the realistic waveguide geometry bounded by a broadband waveguide boundary condition. The data base for the injection of the beam in the output circuit is derived from the steady state solution of a two dimensional simulation of the first klystron cavities. The interface between rotationally symmetric and nonsymmetric part includes not only the particle parameters but also the electromagnetic field at the interface plane.. Results are presented for a 150 MW S-band klystron, which was designed and built at the Stanford Linear Accelerator Center (SLAC) as a part of an international collaboration with Deutsches Elektronen Synchrotron (DESY). The simulations were performed by using the electromagnetic simulator MAFIA.