Study of astrophysical collisionless shocks in the laboratory*

High Mach number astrophysical plasmas can create collisionless shocks via plasma instabilities and turbulence that are responsible for magnetic field generations and cosmic ray acceleration.  With the advent of high-power lasers, laboratory experiments with high-Mach number, collisionless plasma flows can provide critical information to help understand the mechanisms of shock formation by plasma instabilities and self-generated magnetic fields. A series of experiments were conducted on Omega and the National Ignition Facility to observe: the filamentary Weibel instability that seeds microscale magnetic fields [1, 2]; collisionless shock formation (seen by an abrupt ~4x increase in density and ~6x increase in temperature); and electron acceleration distributions that deviated from the thermal distributions [3]. In addition to the case of collisionless shock formation under unmagnetized initial condition, shock formation under magnetized environment is also being studied. Experimental results along with theoretical interpretations aided by particle-in-cell simulations will be discussed.

 

[1] H.-S. Park et al., HEDP 8, 38 (2012)

[2] C. Huntington et al., Nature Physics 11, 173 (2015)

[3] F. Fiuza et al., Nature Physics, 16, 916 (2020)