Research Of X-Band Multi-Beam Klystron

High-Power klystron originates from High-energy electron linac.Health-care accelerators use multi-beam klystron as the power source because it's small and stable.Select X band as it's working waveband to reduce size.How to make sure output cavity can support high output power as it can up to MW is the problem need to be solved.This article focused on the research of X-band multi-beam klystron's double gap output cavity.Researches of double gap or three gap output cavities are mostly theory research.This article focus on multi-beam situation:?1?Firstly we need to confirm working frequency and working mode by adjusting outer radius and inner radius of coaxial cavity.Then confirm the position and radius of electronic channel.Finally we need to confirm the coupling aperture's parameter.Simulation of the structure shows that:double gap output cavity can reduce the electron field to 50%of single gap,decrease breakdown probability,increase R/Q more than doubled and output bandwidth almost 43%.?2?During the processing,we need to adjust the simulation parameters slightly,considering the limit of engineering accuracy and assemble.Measurement of the S parameter shows that working frequency is lower than expected,so the structures need to be tuned.In order to measure the electron field,we need to build an automatic system.Considering the engineering accuracy and cavity's crevice,finally actual test shows that f₀=9.315GHz,bandwidth is 117MHz,Q_ext=79.6,within the margin of error,the results of measurement generally align with the results of simulation.?3?Using Magic to simulate the high-frequency structure,and compare the calculated results of the eigenmodes of the double-gap output cavity with the previous HFSS calculation results,including the resonant frequency and the electric and magnetic field distribution.The two are consistent and also verify the accuracy of the calculation results.The overall PIC calculation results are still in the preliminary stage,and there are problems such as unstable working modes and poor signal excitation effects.The ideal large-signal interaction results have not been obtained and remains to be studied.