Research On The Technology For Generating High Power Microwaves Based On High Power Klystrons

In this dissertation,high power microwavegeneration technology based on power combining and pulse compression of high power klystrons were studied.Compared with the high power microwave system based on oscillators,the high power microwave systems based on power combining and pulse compression of klystrons could long-term operating with high repetition frequency,have characteristics of high energy efficiency,long pulses and stable frequency,power and phase which will benefit for power combing.In addition to be widely used in large scale particle accelerators,this type of high power microwave system could also be used ashigh power radar transmitters,high level electromagnetic environment generators and directed energy weapons.High power klystrons and the SLED pulse compressor with high efficiency and simple structure were chosen for generating high power microwave.Firstly,the transient characteristics of resonant cavities during the charging process and theory of passive SLED pulse compression were analyzed.Effect of unload quality factor,coupling coefficient and phase shifting time,switching speed on the peak power gain and energy efficiency of SLED pulse compressor were investigated.To overcome the problem of high peak power gain and high energy efficiency cannot be achieved at the same time in passive SLED pulse compressor,a novel active SLED pulse compression method with higher coupling coefficient during the charging process and lower coupling coefficient during the discharging process was proposed.Secondly,a high power microwave system based on power combining and pulse compression of high power klystrons were designed and established at S-band.A solid state induction modulator and pulse transformer were used to drive two klystrons in parallel,after power combining and pulse compression,the peak power had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz.The power combining efficiency of klystrons is more than 97%,the peak power gain of SLED pulse compressor is about 4.7 while the energy efficiency of this high power microwave system is about 9.8%.Effect of phase shifting time and switching speed on the peak power gain and energy efficiency of SLED pulse compressor had been verified in experiments.At last,experiments were carried out to verify the active SLED pulse compression method proposedpreviously.TR tube with ignitor was first employed in active RF pulse compression and a switchable coupling coefficient module with H-Twaveguide junction,TR tube and movable short was designed.An experimental active SLED pulse compressor with single resonant cavity was built when a high power circulator was used to replace the 3 dB coupler in SLED pulse compressor.The coupling coefficient was changed from 20 to about 5 at the instant of phase shifting time,a high peak power gain about 6.5 was achieved and the energy efficiency was improved at the same time.Integration with the traditional microwave subject is one of the development directions of high power microwave technology.Technology of RF power source in particle accelerators was appliedto the fields of high power microwave in this dissertation and the research will have some reference value for the development of high power microwave technology.