Effect of barrier layers in burn-through experiments with 351-nm laser illumination

Technical Report · Thu Feb 01 04:00:00 EST 1990

DOI:https://doi.org/10.2172/7016007· OSTI ID:7016007

Delettrez, J.; Bradley, D. K.; Jaanimagi, P. A.; Verdon, C. P.

The time-resolved x-ray emission is measured from spherical targets consisting of glass shells overcoated with plastic in which thin signature layers are embedded. These targets are illuminated at 351 nm by the 24-beam OMEGA laser system at the Laboratory for Laser Energetics of the University of Rochester. We measure a large burn- through rate for bare plastic targets, which can only be replicated in 1-D hydrodynamic simulations with laser intensities in excess of ten times the nominal intensity. We observe that the burn-through times are affected by the presence of a thin outer coating (barrier layer). The burn-through times depend strongly on the barrier-layer material and thickness, whereas one-dimensional simulation results predict only a small effect. Several processes are considered to explain these results: illumination nonuniformity, early shine-through of the laser light through the plastic, prepulses, filamentation, self-focussing of hot spots, and the Rayleigh-Taylor instability. We conclude that mixing due to the Rayleigh-Taylor instability, enhanced by early shine-through, is the most probable cause of the observed large burn-through rates. 27 refs., 8 figs., 1 tab.

• Research Organization: Rochester Univ., NY (USA). Lab. for Laser Energetics
• Sponsoring Organization: DOE/DP; ESEERC; NYSERDA; ONTHYD; ROCHESU
• DOE Contract Number: FC03-85DP40200
• OSTI ID: 7016007
• Report Number(s): DOE/DP/40200-113; ON: DE90006806
• Country of Publication: United States
• Language: English

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