Research On Computer Simulation Methods Of High Power Klystron

The klystron with high power, high efficiency and other advantages, is widely used in radars, satellite navigation, communications, linear or circular accelerators and other fields. With the development of new cavity structure models and related technologies, it towards to the higher power, higher frequency, wider bandwidth and miniaturization. The output parameters are mainly influenced by resonant cavities, input and output circuits, the interaction circuit.The multi-gaps cavity with the high characteristic impedance, low gap voltage and high power tolerance, is widely used in high power broadband klystron. It is vital to design a steady-operation double-gaps cavity. This paper studies on designations of double-gaps cavities and double-gaps klystron interaction process.The external quality factor is the key component of the input and output circuit in a klystron, and its performance is directly related to the bandwidth and output power. Discussing the calculating methods of the Qext and researching advantages and disadvantages have guiding significant to design an input or output circuit.The beam-wave interaction process is the most complex and time-consuming process in a klystron’s designation and simulation. It is extremely important to study on the characteristics in various methods, and then search an reasonable and efficiency simulation.To research the design method of a resonant cavity, calculate the input and output circuit, and simulate the beam-wave interaction, using the CST MWS and the particle simulation software to aided analysis, this paper has carried out many simulations, which mainly contents:1 Research the methods to design high characteristic impedance double-reentrant cavities and double-gaps cavities. Study the influence of important parameters on the mode frequencies. Analyze the electromagnetic field distributions and characteristic impedance in different modes.2 Use the particle simulation software to simulate an S band double-gaps klystron, and get the 86 MW output power and 51% efficiency. Compared with output parameters in the same structure of a single-gap cavity klystron, it shows advantages in output power and efficiency.3 Analysis and Summarize the calculation methods of the Qext. Analysis the advantages and disadvantages of various methods.4 Use the Particle simulation software to simulate an X band klystron. Analysis the influence of some key parameters on the output power and efficiency. Use the MTSS to simulate the structure and analysis the distribution characteristics of the voltage and current. Discuss the influence of different simulate methods on beam wave interaction process.