Measurement of the Growth of Perturbations on Blast Waves in a Mixed Gas |
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| Authors: | A D Edens R G Adams P K Rambo I C Smith J L Porter T Ditmire |
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| Institution: | (1) Sandia National Laboratories, Albuquerque, NM 87123, USA;(2) University of Texas at Austin, Austin, TX 78712, USA |
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| Abstract: | We have performed a series of experiments examining the properties of high Mach number blast waves. Experiments were conducted
on the Z-Beamlet laser at Sandia National Laboratories. We created blast waves in the laboratory by using ∼1000 J laser pulses
to illuminate millimeter scale solid targets immersed in gas. Our experiments studied the validity of theories forwarded by
Ryu and Vishniac (1987, 1991) and Vishniac (1983) to explain the dynamics of perturbations on astrophysical blast waves. These
experiments consisted of a systematic scan of the decay rates of perturbations of known primary mode number induced on the
surface of blast waves by means of a regularly spaced wire array. The amplitude of the induced perturbations relative to the
radius of the blast wave was tracked and fit to a power law in time. Measurements were taken for a number of different mode
numbers in a mixed gas consisting of 7.5 Torr xenon and 2.5 Torr nitrogen and the results are compared to theoretical predictions.
It is found that two of the three mode numbers imply one polytropic index while the third case, which is the most complicated
for several reasons, implies a higher polytropic index. |
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| Keywords: | Vishniac overstability Z-beamlet KiloJoule laser Laboratory astrophysics Blast wave Radiating shock |
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