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K. K. Dannenberg, R. P. Drake (University of Michigan), M. D. Furnish, J. D. Knudson, J. R. Asay, D. E. Hebron (Sandia National Laboratory), D. Schroen-Carey (Shafer Corporation), A. Poludnenko, A. Frank (University of Rochester), D. Arnett (University of Arizona)
Studies of the interaction of a shock wave with a molecular cloud, whether by computer simulation or by experiment, often treat the cloud as a region of uniform density. However, it is well known that actual molecular clouds contain dense clumps. Because these clumps influence the progression of shocks, an experiment has now been designed that includes such ``clumpy" regions. The typical molecular cloud contains regions of locally higher density, with an average density ratio of 40:1 or more at a ~ 5% volume filling factor. The experimental requirements are as follows. The clump volume fraction and the clump to cloud density ratio should be realistic. The shock wave that penetrates the clumpy medium should be strong enough to convert the clumps to plasma. The experiment must be diagnosable. The experiment will be performed using ``Z," a ``Z-pinch" at Sandia National Laboratory. We will show how Z can be used to produce a blast wave within a layer of ``dense" carbon foam. When this blast wave reaches a layer of lower-density foam, which contains the dense clumps, it will drive a shock wave into it at about 45 km/s. The speed and structure of the resulting shock wave will be diagnosed now; later experiments will examine the structure of the medium. We plan to compare the results of these experiments with those predicted using adaptive mesh astrophysical computer codes. This work is supported by the U.S. Department of Energy, NASA and the NSF.