Coincidence of density jump and plasma emission front induced by transversely excited atmospheric-pressure CO2 laser bombardment at low and high pressures

In order to confirm the validity of a model of laser-induced shock-wave plasma generation, the highly sensitive detection of density jump caused by a shock wave was carried out simultaneously with the emission of propelled atoms from a target. A special interferometer which utilized rainbow refractometry was devised. The laser light of a Transversely Excited Atmospheric-pressure (TEA) CO2 laser (600 mJ, 100 ns) was focused on non metal targets. The front of the propelled atoms and the front of the blast wave almost coincide and move together at the same speed during the initial stage of the plasma expansion. During the later stage, however, the front of the propelled atoms begins to fall behind.