Supersonic propagation of an ionization wave along a laser beam

The propagation mode of a discharge is deduced from the gas pressure p(0) ahead of a wavefront, together with the light intensity q(0). It is noted in light of this method that if q(0) exceeds the threshold q(thr) in the generation of a fast ionization wave (FIW), the discharge propagates in the FIW mode. If q(0) is lower than q(thr), the discharge travels in the light detonation mode. Emission is noted to be possible in the case of heavy gases only if p(0) is much lower than 1 atm and the laser beam is wide.