Plasma On The Output Properties Of Microwave Tubes

Plasma microwave electronics is a cross-discipline of microwave, microwave electronics, gas electronics and plasma electronics. In recent several years, it is one of the most rapidly developing to research the interaction mechanism of the traditional microwave devices filled with gas or plasma.In this dissertation, the PIC method was used to study the effective plasma loaded. There are two primary studies: 1. through particle diagnosis, we studied the mechanism of pulse shortening phenomena of plasma filled RBWO by KARAT; 2. we also studied the ion noise of neutral background gas filled klystron by OOPIC. The major results are listed as the following:1,We studied the mechanism of pulse shortening phenomena of plasma filled RBWO. The KARAT method was used to study the influence of microwave pulse of full filled neutral gas RBWO and subparagraph filled. We also compared the microwave pulse in RBWOs that filled with different types of neutral gas. The result shows that:(1) Pulse shorting will appear when the density of gas is too high.(2) The rate of plasma producing is relative with the charge of molecule.(3) Too high density of plasma is adverse to beam gathering.(4) When plasma density reaches a certain value, the resonance absorption happens and the microwave energy is absorbed.(5) The result of subparagraph filled shows that: the gas that filled in the forepart and back end of the slow wave structure has little impact on output microwave, and there is a serious impact on output microwave by the gas that filled in the middle part.2,We also studied in ion noise of neutral background gas filled klystron by OOPIC. The PIC method was used to get the ion noise pictures of output signal. The interaction among beam electron, ion, secondary electron and electromagnetic field is illustrated. The mechanics of ion noise is analyzed. It shows that:(1) Phase fluctuation in output signal is caused by the change of the beam current DC velocity which is affected by the change of the ion amount. The ion interacts with beam electron and has no equilibration state. (2) Secondary electron's amount is small and it has little affection on ion noise, but its behaviors reflect the process of ion noise.(3) The amplitude fluctuation of output signal was caused by the change of beam velocity and beam radius. It was also affected by the ion behaviors.