Numerical Modeling of Laser-Driven Experiments to Study Astrophysical Processes in Magnetized Turbulence

University Of Chicago, Chicago IL

Investigators

Abstract

The goal of this project is to use numerical simulations to design and analyze experiments at the world's most energetic laser facilities to demonstrate and study high energy astrophysical processes in the laboratory. Magnetic fields are present throughout the universe and play critical roles in astrophysical phenomena, such as the acceleration of extragalactic charged particles, cosmic rays which can reach energies that are a billion times larger than those achieved in the Large Hadron Collider, the world's highest-energy particle accelerator. However, the origin of cosmic magnetic fields is not fully understood. The consensus among cosmologists and astrophysicists is that they are the result of the amplification of tiny seed fields, which are stretched and twisted by turbulent motions in astrophysical plasmas -- a process called turbulent dynamo. The magnetized turbulence then mediates the propagation and acceleration of cosmic rays as they randomly scatter with the tangled magnetic fields. These astrophysical processes occur frequently in space but are extremely hard to recreate in terrestrial laboratories. The goal of this project is to design and model laser-driven experiments that will demonstrate for the first time in the laboratory (1) the turbulent dynamo mechanism in the radiative, compressible regime, and (2) the acceleration of charged particles via second-order Fermi acceleration in magnetized turbulence. These experiments will be carried out at the Omega Laser Facility at the Laboratory for Laser Energetics at Rochester, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, and the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. The effort will exploit the mature TDYNO (turbulent dynamo) experimental platform, which was developed and deployed in a prior highly successful three-year experimental campaign at Omega and NIF. The experiments will be designed through simulation campaigns using FLASH, the highly capable radiation magneto-hydrodynamics code developed by the University of Chicago, and large-scale three-dimensional simulations on the Mira BG/Q supercomputer at Argonne National Laboratory. The simulations are critical to ensuring the laser-driven experiments achieve the plasma conditions necessary for these processes to operate; determining when to fire the diagnostics; and interpreting the results of the experiments. The results of the project will be of broad interest to the plasma and astrophysics communities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.