Simulation of the Photoconductive Vacuum Diode Arrays

Photoconductive Vacuum Diode Arrays (PVDA) based terahertz emitter could bring prosperity in the field of communication, imaging and remote sensing. In this paper, the Photoconductive Vacuum Diode Arrays are designed for investigating the high current density electron transmission characteristics. Simulations of conceptual vacuum diode arrays have been implemented using a Particle in Cell (PIC) software. With the effect of space charge limiting, increasing the current density of the emitting surface will reduce the pass rate of electrons. When the initial kinetic energy of the particle is 0.5V and the emission current density achieve 100 A/cm(2), the 5 x 5 square array consisted of 25 vacuum channels with radius of 2 mu m, could transport electrons with current density of at least 82.3 A/cm(2) as the anode voltage no less than 5 V. Furthermore, the electronic flight time reach to 3x10(12) s, which can be operated at terahertz frequency. Since a series of chemical reactions occur during the preparation of photocathodes and cannot be accurately controlled, the influence of initial kinetic energy of 0.5 V-1.3V on electron transport is considered. When the number of channels increases to 100, the anodes received current density of 478.15 A/cm(2) if the voltage increased to 25V and the initial kinetic energy of the particle is 1.3 V, the electrons transmission efficiency has increased to 95.63%. To summarize, this paper analyzed the influence of electrons with current density, initial kinetic energy and the anode voltage on electron transport and through the simulation to get larger electron transmission rate.