Research On Ku-band Overmoded Hpm Generator With Sws Operated At Low Magnetic Field

A Ku-band overmoded high power microwave generator with slow wave structure operated at low magnetic field is put forward in this thesis. Related theoretical analysis and particle simulation are carried out on this proposed device. The results reveal that it is possible to design a GW level HPM generator in Ku band with low guiding magnetic field. Specific contents of the thesis are as follows:Firstly, theoretical analysis about related physical problems is performed. More precisely, dispersion characteristics of rectangular SWS is studied with analytical and numerical methods; coupling impedance of the slow wave device is investigated, which involves the influence of the beam radius and harmonic order; the minimum required magnetic field is estimated for the purpose of maintaining the electron beam balance and controlling its fluctuations, while the cyclotron resonance point are forecasted to avoid resonance absorption; the merits of overmoded structure including high space limiting current permission and large power capacity are discussed, as well as several usual mode selection methods.Secondly, in the particle simulation part, parameters that affect beam-wave interaction are discussed, such as slow wave period, depth of SWS sheet, guiding magnetic field, beam voltage and so on. Based on the discussion and further optimization, an output microwave with frequency of 14.38GHz and average power of 1.1GW is achieved, under the condition of diode voltage 500kV, current 5.8kA and guiding magnetic field 0.7T. The conversion efficiency reaches 37.9%, and the main mode in the SWS is TM₀₁. In addition, device with higher frequency in Ku-band is explored. Eventually, by the introduction of a front reflecting cavity and adjustment of the SWS, the new device generate a microwave of 14.96GHz frequency and 1.2GW power, with the diode voltage 600kV, current 6.8kA and guiding magnetic field1.0T. According to the simulation results, the reflecting cavity is beneficial to promote the beam- wave interaction.Finally, the initial experimental plan is considered, which consists of constructing experimental system, designing the generator and guiding magnetic field. Also, the experimental measurements and related potential problems are discussed. Finally, the initial experimental plan is considered, which consists of constructing experimental system, designing the generator and guiding magnetic field. Also, the experimental measurements and related potential problems are discussed. Specifically, the experimental system is composed of the accelerator platform, the slow-wave generator, the corresponding vacuum supporting equipment, and measuring instruments; the maximum sizes of the generator on both radial and axial directions are 22.8cm and 45.5cm respectively; the guiding magnetic field is supposed to be realized by solenoid coils driven by 4 capacitors with 180μF capacitance and 2.0kV charging voltage. The peak current of the coil is 500A, which will take 4ms to reach; for measuring the Ku-band microwave in this model, the frequency-mixing method is suitable for frequency, and far-field method for the mode and power.