Abstract
The pressure and pulse length dependence of the threshold intensity for optical frequency breakdown of N2 and Ar has been studied using 106 μm pulses from an Nd3+ laser. The pressure range covered was from similar 1-105 Torr and the pulse duration (which is approximately twice the FWHM value) from similar 40 ps-50 ns. At low intensities less, similar 1012 W cm−2 the results are shown to satisfy a simple scaling law of the type found in the analysis of DC breakdown data.