Theoretical And Experiment Study On Magnetized Plasma-filled Relativistic Microwave Devices

Based on the Prof. Liu's theory on the wave propagation along magnetized plasma-filled waveguide, the detailed theoretical and experimental study on wave propagation characters in magnetized plasma-filled cylindrical waveguide and corrugated waveguide are made in this dissertation .In order to get higher output power and higher efficiency in a microwave tube, much progress has been carried out in this regime. Up to now, in relativistic microwave devices, the maximum pulse output power can reach 1GW, and a 1MW CW output power can also be obtained. However, There exist some basic limits for further enhancement of the output power and the efficiency of the microwave devices. The major limit comes from the space charge's influence. The repulsion of electrons in vacuum limits the electronic density in electron beam, resulting in a low efficiency of beam-wave interaction. Recently, much attention has been made on the study of plasma-filled high-power microwave devices for the enhancement of efficiency and output power. The introduction of plasma into generators of coherent electromagnetic radiation potentially has several beneficial effects (a) due to the charge neutralization in the plasma, the devices can operate with large beam current above the vacuum space-charge limiting; (b) the guiding magnetic field can be lower through auxiliary beam focusing of the plasma, so that the volume, weight and total cost of devices can be decreased; (c) the efficiency of devices can be greatly enhanced with a result of the new interaction mechanisms of plasma, electron beam and electromagnetic wave,(d) the working frequency is tunable, leading to a broader bandwidth.In this dissertation , the theoretical and experimental studies on plasma-filled high-power microwave devices in both the corrugated waveguide structure and cylindrical waveguide have been made. The main works are the following:1. The effects of ion-channel, spatial charge and current limiting are discussed in the process of the relativistic electron-beam transporting inplasma.2. The dispersion relations of magnetized plasma-filled corrugated and cylindrical waveguide have been obtained. The dispersion curve and linear gain have been gotten for different physical parameters. The influence of magnetic field, thickness of annular plasma, the density of plasma and the position of annular electron beam are investigated.3. The expression of power density has been derived. Power density, phase velocity and coupling impedance have been also calculated and analyzed.4. With ion-channel and finite field being taken into account, the dispersion relations of cylindrical and corrugated waveguide have been derived in a more general form.5. The properties of the electromagnetic wave propagation along plasma waveguide with a dielectric-rod inside are also studied.6. Some experimental works on the PASOTRON have been carried out.