Simulations of Laser Experiments to Study the Origin of Cosmic Magnetic Fields

PI Name: 
Petros Tzeferacos
PI Email: 
petros.tzeferacos@flash.uchicago.edu
Institution: 
University of Chicago
Allocation Program: 
ALCC
Allocation Hours at ALCF: 
60 Million
Year: 
2016
Research Domain: 
Physics

Magnetic  fields  are  ubiquitous  in  the  universe,  but  their  origin  is  not  fully  understood.  A  variety of ways have been proposed in which seed magnetic fields could be created. It is widely thought that the larger values of the cosmic magnetic fields that we observe are a result  of  the  amplification  of  these  seed  fields  by  the  nonlinear  turbulent  dynamo  mechanism. However, this mechanism has never been demonstrated in the laboratory. We have conceived experiments designed to demonstrate nonlinear turbulent dynamo in the laboratory,  providing  a  comprehensive  picture  of  the  energy  cascade  in  magnetized,  turbulent plasmas. The experiments utilize high-­intensity lasers at the Omega laser facility at  the  Laboratory  for  Laser  Energetics,  and  the  National  Ignition  Facility  at  the  DOE  national  laboratory,  Lawrence  Livermore  National  Laboratory.  We  have  been  awarded shots on both – highly competitive – facilities. These powerful lasers allow us to produce strong  turbulence  and  large  magnetic  Reynolds  numbers  required  for  the  nonlinear  turbulent  dynamo  mechanism  to  operate.  The  experiments  are  designed  and  interpreted using  validated  simulations  done  with  FLASH,  a  highly  capable  radiation-­MHD  code  we  have developed. FLASH simulations are vital to ensure the experiments achieve the desired flow  properties.  They  must  be  3D  to  capture  the  turbulence,  and  they  must  resolve  the  small  spatial  scales  at  which  amplification  occurs.  FLASH  simulations  are  also  critical  in determining  diagnostics’  timing,  since  the  signals  last  only  a  few  nanoseconds.  Finally,  validated FLASH simulations are crucial to interpreting the results of the experiments. This allocation supports NIF experiments that will not succeed without 3D FLASH simulations on Mira.