Shocked silica aerogel radiance transition

Silica (SiO2) aerogel is widely used in high-energy-density shock experiments due to its low and adjustable density. Reported here are measurements of the shock velocity, optical radiance, and reflectivity of shocked SiO(2 )aerogel with initial densities of 0.1, 0.2, and 0.3 g/cm(3). These results are compared with similar data from three solid polymorphs of SiO2, silica, quartz, and stishovite with initial densities 2.2, 2.65, and 4.3 g/cm(3), respectively. Interestingly, below a brightness temperature of ??(????????h??)asymptotic to 35,000K, the slope of the radiance vs shock velocity is the same for each of the SiO(2 )aerogels and solid polymorphs. At ??(????????h??)asymptotic to 35000K, there is an abrupt change in the radiance vs shock velocity slope for aerogels, but not seen in the solid polymorphs over the pressures and temperatures explored here. An empirical model of shock front radiance as a function of SiO(2 )density and laser drive parameters is reported to aid in the design of experiments requiring maximum shock front radiance. Published under an exclusive license by AIP Publishing.