Supernova in the Lab: The Mixing of Extreme Events

Benjamin Musci, Georgia Institute of Technology

Photo of Benjamin Musci

The presented work focuses on the initial testing and validation of a novel experimental facility in the Georgia Tech Shock Tube and Advanced Mixing Laboratory, which allows for the study of blast-driven turbulence in a cylindrical geometry. Motivated by applications to aspects of inertial confinement fusion and the discrepancies observed between actual and modeled supernovae, this newly fabricated facility aims to fully resolve the important spatial scales of the hydrodynamic mixing in these extreme events.

The facility generates a point-source blast wave using a small detonator, which then interacts with a gaseous, membraneless interface of differing density, allowing for the fundamental study of the combined Richtmyer-Meshkov instability (RMI) and Rayleigh-Taylor instability (RTI) in a cylindrical geometry.

The capability of the facility to use simultaneous planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) allows for both quantitative and qualitative analysis of the mixing process and turbulence transition. We are interested in if, and how, the initial conditions, or initial shape of the interface, affects the flow's transition to turbulence.

The original experimental plan involved the use of exploding bridge wires (EBW) to generate blast waves. However, high-speed Schlieren photography generated during initial testing proved EBWs could not achieve the scaling required to represent SN hydrodynamics. Consequently, detonators were integrated into the experiment in order to reach the required scaling parameter, known as the Euler number.

Validation of the crucial aspects of the facility's performance are presented to show that these phenomena can be faithfully and repeatedly reproduced. These include the approximate point source generation of a blast wave with small variation from shot to shot. The creation of a gaseous interface also is verified using PLIF. The trajectory of the gaseous interface after interaction with the blast wave has also been determined using PLIF in order to determine the maximum possible field of view for future diagnostics. The elimination of reshock, boundary layer and fragmentation/debris effects have also been considered. The future work of this facility will enable the study of compressible, diverging, cylindrical and RTI-driven mixing.

Abstract Author(s): Benjamin Musci, Sam Petter, Devesh Ranjan