An Oscillation-Free, HOM-Suppressed Klystron Amplifier

The high-power radio frequency (RF) amplifiers and microwave oscillators, used in the klystrons that power accelerators for high energy physics research, require stability, efficiency, and reliability. Parasitic oscillations, which limit klystron performance, are caused by beam interaction with unwanted klystron cavity eigenmodes and by the feedback of signals between adjacent cavities. This project will explore a concept for an oscillation-free klystron, based on recent advancements of Photonic Band Gap (PBG) structures. The PBG structure will be introduced into a klystron to provide stable, single-mode operation, and solutions to the out-coupling problem will be designed for a wide range of parameters. In Phase I, a PBG klystron will be designed with large cavities that have non-oversized interaction cross-sections. Special attention will be paid to the design of rod-loaded couplers, penultimate cavities, output structures with suppressed excitation of unwanted modes, and beam stability. Commercial Applications And Other Benefits as described by the Applicant: The PBG klystron should find use as a moderate-power, X-band microwave source in high-yield, medium-energy electron linear accelerators for myriad applications in industry and medicine. In addition to accelerator and klystron applications, special PBG-resonators and PBG-waveguides could be used to extract RF energy without parasitic interactions and produce power in applications related to radar communications and defense.