Research On The Novel High-power Microwave Pulse Compressors

Microwave pulse compressors are very important in accelerator and high-power microwave fields.They can enlarge the output power by compressing the length of the input microwave pulse,which have been studied for more than 40 years.There are many challenges to be overcomed when researching the pulse compressors,such as the reduction of the size,the improvement of the power gain and the efficiency and the shape of the pulse needed by the accelerators.The thesis arms to solve these problems and includes the novel method for pulse compression,the design and fabrication of some microwave devices and the shaping of the pulses.In the thesis,the pulse compressors are analyzed in both the time and frequency domains.In the time domain,the procedure of the pulse compression is described by the theory of microwave transmission line.And in the frequency domain,the frequency responses of the pulse compressors can be obtained from the microwave network of them.In addition,the input and output pulses can be calculated by these frequency responses.Based on these theories in the time and frequency domains,the S-band spherical pulse compressor with dual-mode polarizer was studied.The weight of this pulse compressor was 50 kg and the length between the microwave ports was 230 mm.The pule compressor generated the microwave pulses with pulse length of 300 ns and peak power of 566 MW.From the year of 2015,Tsinghua University started collaborating with CERN for researching the pulse compression which is of great significance to the compact linear collider based on klystrons.The compact correction cavity chain,by using which the SLED pulse compressor can generate the flat pulse with ripples,was designed for this project.And anther method named PM-AM modulation technology was applied to eliminate the ripples.Both the correction cavity chain and the PM-AM modulation technology work by changing the shape of the input pulses.The feasibility of the PMAM modulation technology was verified at the Tsinghua high power facility with two klystrons.In the experiment,the output pulse of the SLED pulse compressor was tuned to flat shape.In the aspect of pulse shaping,the concept of high efficiency pulse compression was also verified.The rising edge of the modulator can modulate the shape of the microwave pulses generated by klystrons.The shaped pulses can enlarge the efficiency of the pulse compressor.In addition,the using of the rising edge can reduce the pulse length of the modulator which can improve the energy efficiency of the system.The study of the high-power gain pulse compression was based on the researches of the compact pulse compressor and the pulse compressor with correction cavity chain.A compact two stage pulse compressor based on the spherical resonant cavity was designed for the high-power test facility with two klystrons.This pulse compressor can generate microwave pulses with length of 100 ns and power gain of 20.The analytical and designing methods of the novel pulse compressor was described in the thesis.Some resonant cavities and microwave devices were designed and fabricated for this two-stage pulse compressor.They lay the foundation of the upgrade of the high-power test facility with two klystrons.