Novel design of a micro-pulse electron gun

The development of the micro-pulse electron gun (MPG) mainly relies on the mechanism of the evolutionary process for the multipacting effect. On the other hand, mitigating the limitations of multipacting is what we needed. Here, a new kind of cavity shape is proposed to confine multipacting effect within the spatial range of electrodes, which is of interest to avoiding the occurrence of multipacting in the copper cavity. Based on the theoretical analysis of the saturation process, it is found that increasing the number of impacts for electrons until to saturation is important to attain high quality bunches, while at the expense of losing out-of-phase electrons. In this paper, a novel electrode structure is studied in detail using both theoretical analysis and numerical simulations in order to improve the performance of the gun. After optimizing the cavity shape and electrode structure, the beam quality and saturation currents are maximized and the simulation results are presented.