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Material properties experiments using the awe high power laser, Helen

โœ Scribed by Rothman, S. D. (author);Evans, A. M. (author);Eagleton, R. T. (author);Pearson, L. B. (author)


Publisher
Elsevier Ltd
Year
1999
Tongue
English
Weight
605 KB
Volume
23
Category
Article
ISSN
0734-743X

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โœฆ Synopsis


In this report we discuss two experimental programmes recently carried out using the AWE 1 TW Nd-glass laser, HELEN, to determine the properties of materials under shock loading conditions relevant to hypervelocity impacts. In the first experiment a laser heated hohlraum is employed to generate a uniform steady planar shock which is used to derive high accuracy equation of state data using the impedance match method at pressures in excess of those generally available by conventional means and hitherto only achieved in the vicinity of nuclear explosions. The results are shown to be self consistent and reproducible and thus represent a significant new tool in the material modeler's arrnoury. In the second experiment direct laser illumination at lOI W.cm-' is used to generate an attenuating shock in an aluminium target. Direct evidence of a spa11 layer is obtained by means of x-ray backlighting for the first time in such laser driven experiments. A cumulative damage model is required to predict the spallation and a preliminary analysis shows that the Johnson model, with parameters derived from conventional experiments at much lower strain rates, can be used to predict the spa11 thickness at the higher rates associated with the laser experiment. 0 British


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