Suppression of single-surface multipactor discharges due to non-sinusoidal transverse electric field

Abstract

It is of importance to suppress single-surface multipactor discharges in high power microwave devices. In this work, both particle-in-cell (PIC) and Monte-Carlo simulations demonstrate that multipactor discharges can be significantly suppressed by a temporal Gaussian-type transverse electric field waveform. Decreasing the half peak width of the Gaussian electric field can reduce the time-averaged positive charge density on the surface, corresponding to the strength of the multipactor, by an order of magnitude at fixed time-averaged input power. The underlying physical mechanism is revealed by examining the electron impact energy and angle distribution in detail, as well as the dynamic secondary electron yield (SEY) from PIC simulation. For the smaller half peak width and fixed average input power, more electrons striking the surface have energies either below the first crossover or higher than the second crossover of the SEY curve, giving rise to weaker secondary electrons emission and finally resulting in a weaker multipactor discharge. In addition, we give the analytical expressions of the frequency spectrum and phase shift needed to recover a Gaussian-type waveform, which is in excellent agreement with numerical calculations.