Particle-in-cell simulation on plasma near the cathode of high current electron beam source

This paper presented the particle-in-cell simulations on the expansion process of the plasma with a density about 1014 cm-3 near the cathode surface. The plasma expanding with velocity about 1 cm/μs was observed. The expansion process was analyzed based on the observations of the particle distributions, the particle velocity and the axial electric field at different time. The influences of the plasma temperature and plasma formation rate on the plasma expansion process were discussed. It is shown that the appearance of ions strengthens the electric field on the cathode surface, leading to the increase of electron beam density. The electron field at the plasma front decreases with the increase of beam density, thus the movement of ions towards anode can be realized. The plasma expansion ve