Hydrodynamic response from oxygen non-uniformities in glow-discharge polymer (GDP) plastic in OMEGA OHRV experiments
ORAL
Abstract
Simulations and target characterization indicated that inhomogeneity in oxygen content could be a significant seed for Rayleigh-Taylor growth in GDP-ablator NIF implosions. This has been indirectly supported by observation of larger than expected in-flight modulations during NIF GDP capsule implosions, and the realization that such inhomogeneities can result from photo-induced oxygen uptake. In order to investigate the magnitude of the effect of these oxygen heterogeneities on the hydrodynamic response of GDP ablators, oxygen modulations were photo-induced in GDP foils by illuminating the foils with blue light through a periodic mask pattern. The foils were then used as ablators driven on OMEGA by a halfraum to replicate foot conditions on NIF. The resulting optically reflective shock wave was observed using the OMEGA High Resolution Velocimeter (OHRV). Two-dimensional velocity maps were obtained for both oxygen-modulated and unmodulated samples, with the modulated samples showing clear evidence of the propagation of a rippled shock wave as a result of the photo-induced oxygen heterogeneity.
*This work was supported by Department of Energy Contract #DE-NA0001808. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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