Quantitative model of a short-gap breakdown in air

A two-dimensional model of a short-gap breakdown in air is presented consisting of the Poisson equation and the set of conservation equations for electrons, positive ions and stable and unstable negative ions. Recent data on collisional interactions in air are reviewed to determine the transport coefficients, ionization and attachment coefficients and excitation and detachment rates; these are expressed as analytical functions of the local electric field. The conservation equations are formulated in a two-dimensional approximation assuming rotational symmetry. The model is used to study electrical breakdown and discharge formation in a short gap bounded by parallel metallic electrodes at pressures of 1.01, 10.1 and 101 kPa. The results show that at low currents the discharge at all pressures exhibits similar characteristics, typical for a low pressure glow discharges. The calculations were carried out up to the currents of 14.4, 14.3 and 1.35 mA at 1.01, 10.1 and 101 kPa