Optimization of a double-gap output cavity for a high efficiency klystron operating in the X-band

This paper presents the design of a double-gap output cavity for a klystron operating in the X band. First, the bunching circuit is presented. This bunching circuit provides a bunched electron beam used as the input for the final double-gap cavity design. Then two methods are presented to optimize this design, the first one is based on a clustering algorithm using a disk model simulation tool while the second one is based on a gradient descent using Particle In Cell (PIC) simulations. Both geometries provide about 65% efficiency.