Speaker
Description
Collisionless shocks dissipate the incoming flow’s kinetic energy through collective plasma processes rather than particle collisions, and at supercritical Mach numbers this dissipation relies on the reflection of a fraction of the incoming ions back into the upstream region. The resulting counter-streaming of reflected and incoming ion populations can drive ion Weibel instability, characterized by growing quasi-static filamentary currents. We study signatures of this instability at Earth’s bow shock using burst-mode MMS observations of quasi-perpendicular crossings, and compare them to particle-in-cell simulations spanning the same range of Alfvénic Mach numbers. We calculate magnetic field amplification across the shock ramp and overshoot for each crossing and show that it follows the Mach-number dependence predicted by simulations, consistent with a Weibel driven origin. We further corroborate this identification individually through wave analysis, confirming additional individual crossings that show signatures of this instability.