Studies of hydrodynamics relevant to supernovae remnant physics with laser
driven blast waves
Todd Ditmire,
University of Texas at Austin
Abstract: The evolution of hydrodynamic perturbations on radiative blast waves often plays an important
role in shaping the structure of the interstellar medium. For example, the pressure-driven thin
shell overstability, or Vishniac overstability, has been postulated by astrophysicists to account
for much of the structure seen in certain supernova remnants, and may play an important role in
the formation of stars. It was first postulated in 1983 by Ryu and Vishniac as a result of analysis
of the effects of perturbations on thin shell blast waves.
These hydrodynamic phenomena can be studied in the laboratory by the production of high
Mach number blast waves in a gas driven by a high power laser driven explosion. In this talk, I
will describe a variety of experiments which have produced blast waves in gases from the
explosion of a laser plasma. Our experiments use both high energy (100 J to 1 kJ) laser pulses
driving spherical explosions from irradiated solid targets, as well as cylindrical explosions in
gases irradiated by ultrashort pulse lasers. In these laser experiments, we are able to produce
blast waves with velocities up to 100 km/s. We have examined blast waves in a number of gases
of varying composition and density. With these experiments we have, for example, observed
shock trajectories in the radiative and non-radiative regimes, examined the formation of a
radiative precursor ahead of a strongly radiating shock, and compared measured hydrodynamic
perturbation evolution rates with well known theories.