Dynamic nonoptogalvanic signal polarity and magnitude in prebreakdown gas discharges

Nitrogen laser pulse irradiation of prebreakdown discharges in Ne and Ar result in pulse responses strikingly similar to those reported for dynamic optogalvanic signals. For the latter, response polarity depends primarily upon atomic transition. Here, it depends primarily upon bias. Nevertheless, analysis of the results points to similar internal processes within the gas concerning metastable generation and destruction. Photoionization-assisted electron heating is an additional photon process relevant here which changes relative populations of excited states and plays a key role in reversing prebreakdown signal response polarity. It can also explain the mechanism of reported electron temperature increase in optogalvanic experiments which cannot be explained on the basis of atomic transitions.