| In recent years, the high power electron beam source technology, as a new technology, has been developed quickly because of the continuing demands of higher power, higher energy and higher frequency microwave sources in military and scientific research. The pseudospark electron gun works at high voltage and can produce high power electron beam. The ions produced by discharges do not bomb the cathode directly. With so many advantages, the pseudospark electron gun is prospective to be a new kind of beam source. However, the principle of pseudospark discharge is still not very clearly. In order to enhance the high power electron beam focusing, plasma is introduced into focusing system, so the system can operate without a guiding magnetic field. In the dissertation, the properties of pseudospark discharge and the focusing effect of plasma is studied. The main works are as follows:1. Outlining the characteristics of pseudospark, such as pressure and breakdown voltage. The Monte Carlo collision model is described in detail.2. The pseudospark discharge is simulated with the PIC-MCC method. The virtual anode formation time and propagation velocity at different pressure with different apertures are investigated.3. Based on thin annular electron beam approximation, the focusing effect of plasma is investigated. The inner and outer envelops of the annular beam are also derived under different plasma electrons distributions. Two important parameters–balance radiuses and space charge force balance radius is calculated under neutral plasma case. The properties of electron beam transmission are discussed. The transmission period and the amplitude between the peak to peak with different plasma–filled factors are presented. The optimized method of plasma–filled factor to get a small amplitude and long period length electron beam is suggested.4. The inner and outer envelops of the annular beam in plasma are simulated with PIC code. |
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