Investigation of incident laser absorption by vapor plume plasmas

Propagation and properties of vapor plume plasmas generated by Nd:Glass laser pulses intreracting with Ly12 aluminium targets were investigated with high speed photograph technique, and then the sheilding effects of absorption were studied. Experiments show that the optical thickness is up to 1.2 for power densities between 0.7 x 107 W/cm2 and 1.6 x 107 W/cm2. The absorption of vapor plume plasmas is proportional to the incident laser intensity, and the absorption curve vs time of peak pulse was abtained experimentally. The absorptivity is greater at 3 mm apart from the target surface than at 9 mm