Influence of the work function on the electric field at the cathode surface in a diode

The cathode plays an important role in high power microwave devices, the paper studies the time-dependence laws of the electric field at the cathode surface in a planar vacuum diode with a field emission cathode. The influence of the work function on the electric field at the cathode surface has been investigated. To analyze the effects of the space charge of emitted electrons on the electric field at the cathode surface, Poisson´s equation was solved numerically for different parameters of applied electric field in a finite-difference time-domain particle in cell simulation. It has been shown that the self-consistent electric field at the cathode surface oscillates initially and finally yields a steady state, the increase in the value of work function results not only in an decrease in the absolute steady value of the electric field at the cathode surface, but also in an shorter time which is cost to reach the steady state for it.