Multiscale Dynamics of Particle Acceleration in Collisionless Shocks and Magnetic Reconnection Regions in Earth's Magnetotail

Collisionless shocks and magnetic reconnection events are central to energy conversion and particle acceleration in space plasmas. This study investigates the interplay between shock-driven turbulence, reconnection, and energetic particle generation in the near-Earth magnetotail, using a combination of in-situ spacecraft observations and particle-in-cell (PIC) simulations.

We analyze multi-point data from THEMIS and MMS missions during substorm events characterized by dipolarization fronts, bursty bulk flows, and sharp transitions in plasma and magnetic field parameters. The observed signatures of fast electron bursts, enhanced electric fields, and Hall magnetic structures are compared with 2D and 3D kinetic simulations that capture the onset of reconnection and shock steepening.

Simulation results reveal that oblique slow shocks coupled with turbulent reconnection layers can generate localized acceleration zones with strong electric fields (up to several mV/m), where electrons undergo Fermi and betatron acceleration. Ion acceleration is dominated by shock-drift processes, with energy spectra consistent with power-law distributions observed during substorm injections.

Our findings support a unified model in which shocks and reconnection jointly contribute to the energization of particles in the magnetotail, highlighting the importance of multiscale coupling—from ion inertial to electron kinetic scales—in driving space weather phenomena.