Density profiles, electric field and energy dissipation in a short gap breakdown: a two-dimensional model

A two-dimensional model of the short gap breakdown in He has been developed consisting of conservation equations for electrons, ions and metastable atoms and the Poisson equation. Direct stepwise and Penning ionisation are considered and cathode emission takes into account the ion and metastable impact as well as photo-emission. Time development is followed up to 1.11 mu s, when the electron, ion and metastable densities reach maximum values of 1.6, 25 and 180 (*1010 cm-3) respectively.