Experimental study of light reflectivity of the shocked LY12 aluminum unloading to different gases

Spectral radiance histories of plasma for He, D2, and H2+D2 gas mixtures with the initial pressure p0=0.6,1.2 MPa after shock compressed by a two-stage light-gas gun was measured by using transient radiation pyrometer. According to the signal amplitude of spectral radiance history, the reflectivity R of LY12 aluminum base-plate surface after shocked was obtained from a typical record by means of fit. It was found that the light reflectivity R (wavelength ranges 340~800 nm) of shocked LY12 aluminum base-plate surface unloading to He, D2 and H2+D2 mixing gas plasma is about 0.4，which decreases to half of the static state reflectivity( ~0.8). The reason of reflectivity decreasing at dynamic loading is discussed.