Experimental study of the flow induced by a CO2 laser on solid target in rarefied atmosphere

In this paper an experimental study of the flow induced by a CO2 laser in the front of a solid target located in air at pressures varying from 1 bar to 10-5 Torr is reported. Axial and radial flow velocity measurements have been carried out by means of a fast image converter camera. The electron density was measured by laser interferometry. The thermal and mechanical coupling were respectively determined by the measurement of the pressure produced on a target and by the measurement of the target's temperature. A threshold pressure existed in the region of 10 mbar, below which the plasma generated was transparent to the incident ray and consequently the thermomechanic coupling then became important. (author)