Knowledge Bank

A preliminary theoretical study of an explosive-driven argon shock, using measured shock velocities, indicated shock temperatures of $23,000\circ K$. Opacity calculations showed the precursor radiant flux in a tube of 60 cm length should be that of a blackbody of the above temperature up to photon energies near that of the first excited state of argon $(h\nu =11.5ev)$. This total calculated flux is 1.4 megawatts. Flux measurements using ablation and bolometer detectors showed 0.2-0.3 megawatts with little or none of this in the ultraviolet. This low flux can be explained by a high ultraviolet opacity of the cool argon ahead of the shock due to the absorption of resonance line radiation from the shocked gas. Preliminary flux measurements on a tube of 5-cm effective length substantiate this theory.