Abstract
The interaction of strong shock waves, such as those generated by the explosion of supernovae with interstellar clouds, is a problem of fundamental importance in understanding the evolution and the dynamics of the interstellar medium (ISM) as it is disrupted by shock waves. Here we present the results of a series of scaled Nova laser high energy density experiments investigating the evolution of a high-density sphere embedded in a low-density medium after the passage of a strong shock wave, thereby emulating the supernova shock-cloud interaction. The Nova laser was utilized to generate a strong (~Mach 10) shock wave that traveled along a miniature beryllium shock tube, 750 μm in diameter, filled with a low-density plastic emulating the ISM. Embedded in the plastic was a copper microsphere (100 μm in diameter), emulating the interstellar cloud. The morphology and evolution as well as the shock wave trajectory were diagnosed via side-on X-ray radiography. We describe here experimental X-ray radiographic results of this interaction out to several cloud crushing times and compare them to detailed two- and three-dimensional radiation hydrodynamic simulations using both arbitrary Lagrangian and Eulerian hydrodynamics (ALE), as well as high-resolution adaptive mesh refinement (AMR) hydrodynamics. A key result is the first experimental evidence that the cloud is destroyed by a three-dimensional nonlinear bending-mode instability (Widnall instability), confirming earlier predictions with high-resolution three-dimensional calculations.
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