Gas breakdown in inhomogeneous microwave electric fields

Abstract

The main physical properties of gas breakdown in inhomogeneous high frequency microwave electric fields are investigated using both analytical and numerical analysis. In particular, the interplay between diffusion and attachment in redistributing electrons from high field regions to low field regions and the concomitant effect on the breakdown threshold is studied using three different examples of ionization profiles. The results give a clear physical picture of the dependence of breakdown electric field on pressure showing a high pressure branch determined by conditions in the high field region, a low pressure branch determined by the properties of the low field region only, and a more or less smooth transition region for intermediate pressures. Simple estimates for the extension of the transition region are given in good agreement with the numerical simulations, and a comparison of the theoretical breakdown threshold with previous experimental results also shows good agreement.

Frequency response of atmospheric pressure gas breakdown in micro/nanogaps

“…9,10 The DC 11,12 and low RF breakdown [13][14][15] have been addressed extensively through theory, simulations, and measurements. In contrast, gas breakdown due to high frequency time-varying fields especially in micro/nanogaps [16][17][18] remains poorly understood and has not been described by a general scaling law. The AC breakdown problem has been studied since 1950s.…”

Transient Electric Field Shaping With the Linear Combination of Configuration Field Method for Enhanced Spatial Control of Microwave Plasmas

“…As shown in this paper, further undesired plasmas may appear in the cavity. These parasitic discharges are produced where the electric field is enhanced by the geometry of the elements inside the cavity such as the corners and wedges of the sample holder or the object to be processed [27] or the presence of screws, defects, gaps, or metallic grids [28], [29]. These parasitic discharges result from the residual spatial sidelobes during TR focusing.…”