Study of the interpenetration of asymmetric plasma flows with experiments and simulations relevant to quasi-parallel magnetized collisionless shock formation*

Collisionless shocks, where formation scales are much smaller than the collisional mean free path, are found throughout astrophysics and are potential candidates for high-energy particle acceleration and cosmic ray generation. When these shocks form in the presence of a pre-existing magnetic field, the orientation of the shock normal relative to the magnetic field determines characteristics of the shock formation. Quasi-parallel shocks, where this angle is less than 45°, are predicted to be very efficient particle accelerators. However, the underlying physics is not as well understood and challenging to study in the laboratory. We present experimental results from the OMEGA Laser Facility and supporting simulations to study the interpenetration of asymmetric plasma flows in a parallel magnetic field to study early formation processes relevant to quasi-parallel collisionless shock formation. We highlight analysis of Thomson scattering data collected from experiment and compare results with simulations.