Understanding the formation of stars is one of the most outstanding problems in astrophysics. Observations and simulations of star formation show that turbulence, magnetic fields and stellar feedback reduce the star formation rate (SFR) by more than an order of magnitude compared to the gravity-only case, and puts the simulations within a factor of 2-4 of the observed astronomical SFR. In laser-driven experiments on NIF, we propose to experimentally investigate the effects of turbulence and simulated gravity on the compressibility of gases and plasmas similar to those in star-forming molecular clouds in our galaxy, thereby testing theoretical models and simulations of the SFR. Bringing experimental HED science into mainline astrophysics and astronomy and vice versa will have a significant unifying impact on the reach of these two largely separate fields. NIF is uniquely suited for these experiments, as it allows for a hydrodynamically unstable, compressible system to be created and evolved into the deeply nonlinear and turbulent regimes. It also allows the use of larger targets, which helps isolate a central portion of the experimental region from edge effects.
3D view of laser-induced, shock-driven turbulence:
The following movie shows two simulations of a laser-driven shock running into foam (left: without voids in the foam (no turbulence); right: with 25 micro meter voids (-> turbulence)):
The following shows the same simulation as the previous one on the right-hand panel, but here in a three-dimensional, cylindrical geometry (the slice on the right is at y=0.2cm):
This shows a 3D version of the previous movie:
A 600 micro meter thick projection through the 3D simulation shown in the previous movie with 25 micro meter foam voids (left: projected density; right: projected line-of-sight velocity):
Same as the previous movie, but for a simulation with 100 micro meter foam voids:
Same as the previous movie, but smoothed to a diagnostic resolution of 25 micro meter:
Same as the previous movie, but for a 300 micro meter thick projection:
Same as the fist movie, but for the turbulent case with foam voids of size 50 micro meter (left) and 12.5 micro meter (right):
Same as the fist movie, but for the turbulent case with a foam adiabatic index gamma = 1.1 (left) and gamma = 3.0 (right):
The FLASH code was in part developed by the DOE-supported ASC/Alliance Center for Astrophysical Thermonuclear Flashes at the University of Chicago.