The breakdown stage in long laser tubes and plasma focus devices

Abstract

The breakdown stage in a long Xe laser tube and a deuterium filled plasma focus device operating in the mbar pressure range is studied theoretically and experimentally. A simple model for describing the conditions to reach an electron plasma thermalized regime is given and its evolution in terms of the applied voltage is derived. The model is shown to be consistent with the experimental data, and enables determination of the plasma state at the breakdown time in both devices. It is also shown that the stage previous to electron thermalization is the main component of the breakdown time delay in the studied cases, and that the duration of this stage diminishes with the filling pressure, contrary to the expected inverse dependence on the reduced electric field.