PIC simulations in an emissive diode with different flow duration

Summary form only given, as follows. By coupling with the boundary-fitted grid, a two-dimensional quasi-stationary particle-in-cell (PIC) code has been developed to study the pulsed power field-emissive diode when the duration emission varies. The code serves to simulate the electron motion in a self-consistent manner. Since most of the diodes are of cylindrical symmetry, the particles are studied in the r-z plane. Because recent electron accelerator applications such as free-electron lasers and high-power microwave tubes require bursts of very short pulses, evaluation of the maximum current intensity versus emission duration is of interest. Several cases for a planar diode were considered to illustrate the performance of the code. With a constant applied voltage, the current densities approach the space-charge-limited current density. For short electron flow duration with sine-shape voltage pulse, the relations between the peak current densities and the width of the pulses are obtained by the PIC code