Rear surface light emission measurements from laser-produced shock waves in clear and Al-coated polystyrene targets

The Nike KrF laser, with its very uniform focal distributions, has been use d at intensities near 10(14) W/cm(2) to launch shock waves in polystyrene t argets, The rear surface visible light emission differed between clear poly styrene (CH) targets and targets with a thin (125 nm) Al coating on the rea r side. The uncoated CH targets showed a relatively slowly rising emission followed by a sudden fall when the shock emerges, while the Al-coated targe ts showed a rapid rise in emission when the shock emerges followed by a slo wer fall, allowing an unambiguous determination of the time the shock arriv ed at the rear surface. A half-aluminized target allowed us to observe this difference in a single shot. The brightness temperature of both the alumin ized targets and the non-aluminized targets was slightly below but close to rear surface temperature predictions of a hydrodynamic code. A discussion of preheat effects is given. (C) 1999 Elsevier Science B.V. All rights rese rved.