Theoretical And Experimental Researches On Bifrequency Magnetically Insulated Transmission Line Oscillator (BFMILO)

Magnetically Insulated Transmission Line Oscillator (MILO) is a kind of cross-field device, which can generate High Power Microwave (HPM) without external magnetic field. Bifrquency Magnetically Insulated Transmission Line Oscillator (BFMILO) is a variation of that device which can generate HPM with two stable and separate frequencies, named bifrequency. This is a newly developing direction of HPM devices. A novel idea of BFMILO is put forward for the first time, and the model of BFMILO is built. An L-band BFMILO is theoretically analyzed and simulated by Particle-In-Cell (PIC) codes, and it is optimized, designed and experimented. In addition, some technologies relating to BFMILO and other bifrequency and multi-frequency HPM devices are also preliminarily investigated. The main research contents include:Firstly, the investigation background of HPM, the principle of MILO and the actual state of MILO investigation in the world are introduced. Then, the value of BFMILO investigation is explained.Secondly, a novel method of dividing a single device into different azimuthal partition to generate HPM with two frequencies is put forward for the first time in this paper. Resorting to the azimuthal partition of cavity-depth, a novel HPM device of BFMILO is put forward. The operation principle and character of BFMILO are analyzed, and an L-band BFMILO is designed. By the method of numerical calculation, the high-frequency characteristics of BFMILO are investigated, the information such as the eigen-frequencies, field distribution, Q-value of BFMILO's resonating cavities, is obtained. The analyses show that the two different azimuthal partitions are related to two different operation frequencies of BFMILO respectively, and those two azimuthal partitions of the resonating cavities in BFMILO can operate independently.Thirdly, BFMILO is simulated, optimezed and designed taking the method of three-dimensional PIC simulation. The relationship between output microwave power and input voltage, output microwave frequencies and input voltage, are investigated. The spectra of microwave power and fields are also analyzed. Moreover, microwave generation characteristics of BFMILOs with different azimuthal-partition proportion are investigated, the information such as microwave field distritution in the hot cavities, particles in phase space, total output microwave power and spectra, is obtained. When the electron beam voltage is 530 kV and current is about 45.5 kA, a BFMILO can generate about 2.65 GW of HPM with two stable and separate frequencies. They are respectively 1.28 GHz and 1.50 GHz. The power conversion efficiency is about 11%. The amplitude difference of the spectrum between the two frequencies is about 0.4dB. The results confirm the rule that the interaction between electron beam and microwave in BFMILO is separately in different perticular partition once again.Fourthly, a preliminary experiment of L-band BFMILO is carried out. Experimental system and measurement system are built. Measurement and calibration method are introduced. The diode of BFMILO and the emission characteristics of different cathode materials are also investigated. Far-field patterns of the antenna of L-band BFMILO are obtained, and the total microwave power is obtained by integral of power density of radiation field. FFT of the radiated microwave signal gives out two stable frequencies, which indicates an L-band BFMILO is developed successfully. Employing an electron beam of 420 kV , 34kA, an L-band BFMILO can generate HPM with two stable and separate frequencies. They are respectively 1.26 GHz and 1.45 GHz with respective microwave power of 398 MW and 222 MW. The results prove the feasibility that BFMILO can generate bifrequency HPM.Eventually, some other bifrequency and multi-frequency HPM devices are investigated. They might exploit the investigation of bifrequency microwave devices.