Initial Testing Of A Two-dimensional Computer Code For Microwave-induced Surface Breakdown In Air

A two-dimensional, electromagnetic, electron fluid computer code for microwave-induced surface breakdown in air is developed. This code is based on finite difference approximations to Maxwell´s curl equations for TM/sub om/. modes in cylindrical waveguides and electron conservation equations for continuity, momentum, and energy. An implicit, block- iterative, optionally stiff, variable step integrator solves the global set of equations. A 2.856 GHz, 1 MV/m amplitude, radial electric field pulse in a highly dispersive waveguide impinges on two different model field emission structures with the same emission threshold (0.2 MV/m) and rate (10/sup 11//(m/sup 3/-s)). One structure is a perfectly conducting flat end plate; the other is a perfectly conducting axial stub of 0.413 cm radius by 1.69 cm length, centered on a flat end plate. Pressures vary from 50-800 torr. In both cases, peak electric fields occur where expected, initial electron generation is from field emission, and later generation is from avalanching in air. The location of peak generation is at the field maxima. The amount of late time density varies qualitatively with pressure as theoretically expected.