1. Laboratory Astrophysics Simulations Using CRASH Code
M.A. May, C.C Kuranz, M.R. Trantham, Center for Radiative Shock Hydrodynamics at The University of Michigan
ABSTRACT
The purpose of this project is to replicate and study astrophysical
phenomena including supernova explosions, supernova remnant
evolution, and interactions between ionizing radiation waves with
molecular clouds.
Using high-powered lasers, high-energy-density conditions can be
created in a laboratory. Using scaling relationships we can then
relate laboratory experiments to astrophysical phenomena. To
refine our experiments, we run simulations with the already
created HYADES and CRASH codes, radiation-hydrodynamics
simulations.
Implementing CRASH’s two-dimensional capabilities, we are able to
simulate shockwave collisions generated by lasers and analyze
plasma properties as it disperses across different points. From
these simulations, we can determine where kinetic (ram) and
thermal (ion) pressures exist in near balance to the magnetic
pressure.
OBJECTIVES
• Determine time values where kinetic/magnetic and
thermal/magnetic pressures are balanced
• Compare shockwave collision results from CRASH simulations to
empirical results from previous experiments
• Aid in the design of future experiments
METHODS
For training purposes, HYADES was used to run one-dimensional
simulations in which two lasers were directed at each other through
polystyrene foils. The plasma from the shockwaves (result of laser
interaction with foil) would then collide at the midpoint between
the foils.
Using CRASH code, it was then possible to create 2-dimensional
simulations. As in the case of the HAYDES simulation, lasers were
directed through foils separated by 10 mm. Thanks to CRASH’s 2-
dimensional capabilities, data from any point on the xy-plane could
be studied. Selecting three points along the x-axis (5000, 6000 and
7000 microns), data was then analyzed in IDL.
With this information, times when both the ratios between
ram/magnetic pressure and ion/magnetic pressure were between
0.1 and 10 (pressure balance) were determined.
ANALYSIS
CONCLUSIONS
• Kinetic/magnetic and thermal/magnetic pressures exist in near
balance around 80-90 ns . This condition can be studied for
approximately 40 ns if we focus on either 5000 or 6000 microns,
where the condition can be observed for the longest time
interval.
• Comparing our results to empirical results from previous
experiments, it is possible to that conclude simulations are
reliable.
• Next steps: aid in the design of future experiments
(computational and non-computational).
Ionization: Plasma was fully ionized for most of the experiment .
Electron Temperature: After 20 ns, electron temperature decreases
asymptotically.
Plasma Density (ρ): Points closer to center of collision present
larger density values. Additionally, closer points experience changes
in these values sooner (~5ns), and therefore peak sooner (~40ns).
Plasma Velocity (u): Points farther from the center of collision
present larger velocity magnitudes. In this simulation, these values
peak approximately at 20 ns.
Ram Pressure (RamP): After dividing the ram pressure (0.5*ρ*u2) by
the magnetic pressures (MagP) of three different magnetic fields B
(5, 10 and 15T), it was observed that the ratio RamP:MagP was
closest to 1 at approximately 90 ns (10 T). Slightly increasing the
magnetic field results in this ratio decreasing, and therefore in
longer time span to study this condition.
Plasma Beta: After dividing ion pressure by the magnetic pressures
of three different magnetic fields B (5, 10 and 15T), the Plasma Beta
(IonP:MagP) was obtained. The Plasma Beta had values near 1
between 80-90 ns (10 T). Slightly increasing the magnetic field
results in this ratio decreasing, and therefore in longer time span to
study this condition.
ACKNOWLEDGEMENTS
RESULTS
0.1
1
10
100
1000
0 20 40 60 80 100 120
RamP:MagP(logscale)
Time (ns)
Ram Pressure : Magentic Pressure (10 T) vs Time
7000 micons
6000 microns
5000 microns
0.1
1
10
100
0 20 40 60 80 100 120
PlasmaBeta(logscale)
Time (ns)
Ion Pressure : Magnetic Pressure (10 T) vs Time
7000 microns
6000 microns
5000 microns
This work is funded by the NNSA-DS and SC-OFES Joint Program in
High-Energy-Density Laboratory Plasmas, grant number DE-
NA0002956.
I would also like to thank the UROP program at the University of
Michigan for their support.