Research On Broadband Multi-Beam Klystron By Computer Simulation

Some research on computer simulations of the broadband Multi-Beam Klystron (MBK) has been carried out in this thesis. It includes calculations of π mode rectangular coaxial cavities, simulations and optimizations of electron optical system and beam-wave interaction system of the L band continuous wave broadband MBK, thermal analysis and optimizations of the drift tubes of the output cavity and collector of the L band broadband MBK, and some primary research about the multi-beam's characteristic which influences on the performance of the MBK.The three dimensional electromagnetic code of ISFEL3D is used to calculate the half wavelength and quarter wavelength rectangular coaxial cavities. The structures, The EM field distribution and characteristic impedance of operating modes for different cavity structures have been obtained. Also the rectangular coaxial cavities are compared with the double-gap coupled cavities. The results show that the half wavelength rectangular coaxial cavity has similar characteristics of the double-gap coupled cavity with small volume and weight. It can be used in low frequency band MBK.The one dimensional and 2.5 dimensional computer codes for klystrons are used to simulate and optimized the electron optical system and beam-wave interaction system of the L band broadband continuous wave MBK. The optimal design parameters are obtained.A method of thermal analysis and optimization of cooling system of the transfer tube of output cavity and the collector of MBK has been founded. Now it's possible to make more exactly thermal analysis of the output cavity and the collector by existing codes. Some methods of optimization of cooling systems to reduce the highest temperature in the systems have also been proposed.Influence of the multi-beam characteristic on performance of MBK has been researched. The field difference in cavity gap of MBK will influence the output performance. The interaction of multiple beams in cavity gap also been analyzed.