Speaker
Description
Using 2D3V fully kinetic PIC simulations, we investigate how the dominant ion-scale instability regime evolves with Alfvénic Mach number ($M_A = 8.6-23$). At low $M_A$ ($\lesssim10$), the proton cyclotron instability (PCI), driven by ion temperature anisotropy, dominates and is accompanied by whistler-mode waves excited by electron temperature anisotropy in the shock ramp. At high $M_A$ ($\gtrsim20$), the Weibel filamentation instability, sustained by counterstreaming reflected ion beams, becomes decisively dominant. The transition occurs between $M_A = 8.6$ and $15$; the Weibel growth number and the transverse magnetic field amplification both rise, while whistler power drops, revealing a shift from wave-dominated to filamentation-dominated shock dissipation.