Radiation-gas interaction in tube laser-produced spark

Computer simulations of the tube laser-produced spark, created by Bessel optical pulse, are performed. The calculations show a sharp increase of absorption energy when the laser intensity exceeds the threshold by a few percents. The comparative role of thermal conductivity and hydrodynamic effects in the evolution of the plasma channel at above threshold intensities is analyzed for helium and argon. The substance motion lessens electron density and energy absorption in the region of the main maximum of radiation and may enlarge them on the perifery maximums. The last effect is more appreciable for a light gas helium.