Theoretical study of a diode with dielectric-gridded cathode

We investigate the I - V characteristics of a vacuum diode with a gridded c athode. The grid is located on top of a dielectric material that on its bac k side is covered by a uniform electrode. Ignoring space-charge effects, th e current density extracted from the grid is proportional to the dielectric coefficient and it is quadratic with the back electrode voltage. Consideri ng only space-charge associated with the back electrode voltage, it is foun d that the anode current is proportional to the anode voltage. When all spa ce-charge effects are considered, it is shown that the electrostatic energy coupled into the diode gap through the grid is responsible to the excess o f current beyond the Child-Langmuir limit. (C) 1998 American Institute of P hysics. [S0021-8979(98)07224-7].