Theoretical Study Of S-band Magnetically Insulated Transmission Line Oscillator

The magnetically insulated line oscillator (MILO) is a gigawatt-class, coaxialcrossed-field microwave tube closely related to the linear magnetron. The primarycharacteristic of the MILO is that it requires no external magnetic field to insulate theelectron flow under the slow wave structure, so the tube can be compact, lightweightand operate at low impedance. This self-insulating property, inherent in magneticallyinsulated lines, allows the tube to handle an extremely large input beam power(tens ofgigawatts) at modest pulser voltages (several hundred kilovolts) without ensuringelectrical breakdown of the anode-cathode gap, so it is attractive as a source of highpower microwave. This dissertation presents the dispersion relation of the coaxial slowwave structure, the high frequency characteristics of the S-band MILO and particlesimulation.Firstly, progress of MILO research in and out of our country is analyzed andsummarized. The basic theory of MILO operating is introduced.Secondly, according to the dispersion equation of the coaxial slow wave structurein MILO, the dispersion relation of S-band MILO is researched by programming.Thirdly, The high frequency characteristics of the SWS cavity, the closed cavityand the open cavity in S-band MILO are also researched.Finally, a S-band MILO is designed, with the beam parameters of 450kV, 40.1kA,a 2.42GHz, 1.80GW average output power microwave is generated from the optimizedMILO by simulation. The relations among the frequency, output power, powerconversion efficiency and geometry parameters of the S-band MILO are presented insimulation. Three types of improved S-band MILO are also designed and optimized.Simulation results are: when the input voltage is 450kV, the total current is 42.0kA, a2.41GHz, 2.35GW average output power microwave is generated from the firstimproved MILO, the efficiency is 12.4％; when the input voltage is 450kV, the totalcurrent is 41.8kA, a 2.41GHz, 2.20GW average output power microwave is generatedfrom the second improved MILO, the efficiency is 11.7％; when the input voltage is450kV, the total current is 42.1kA, a 2.41GHz, 2.25GW average output power microwave is generated from the third improved MILO, the efficiency is 11.9％.Besides, the three improved MILOs have the same progress: the saturation time isshorter, both the average power and efficiency are higher.