Laboratory Observations of Electron Heating in High-Mach-Number Collisionless Shocks

Collisionless shocks are ubiquitous throughout the heliosphere, from planetary bow shocks to interplanetary shocks driven by coronal mass ejections to the termination shock at the edge of solar system. How these collisionless shocks heat plasmas remains a key heliophysics science question. Theory predicts the total plasma temperature in regions far from the shock interface, but despite decades of observations and numerical simulations, there remains no clear understanding on how energy is partitioned across the shock itself.  Recent experiments [1] demonstrated the laboratory generation of high-Mach-number, magnetized collisionless shocks through the interaction of a laser-driven piston plasma with a pre-formed magnetized ambient plasma, opening up a new regime of laboratory space physics.  We present new experiments utilizing this platform that measure electron heating through high-Mach-number collisionless shocks.  The temperatures are diagnosed with temporally-resolved Thomson scattering, and the results are compared to both particle-in-cell simulations and satellite observations of electron heating in the Earth's bow shock.

[1] Schaeffer et al., Phys. Rev. Lett. 119, 025001 (2017)