Shock Propagation and Associated Particle Acceleration in the Presence of Ambient Solar-Wind Turbulence

TL;DR

This review explores how ambient solar-wind turbulence influences shock surface fluctuations and enhances particle acceleration and transport, especially for low-energy particles, addressing key challenges in space plasma physics.

Contribution

It provides a comprehensive analysis of the role of upstream turbulence in shock dynamics and particle acceleration, highlighting its importance in space weather phenomena.

Findings

Upstream turbulence critically affects energetic particle variability.

Pre-existing turbulence enhances trapping and acceleration of low-energy particles.

Turbulence helps overcome the injection problem at shocks.

Abstract

The topic of this review paper is on the influence of solar wind turbulence on shock propagation and its consequence on the acceleration and transport of energetic particles at shocks. As the interplanetary shocks sweep through the turbulent solar wind, the shock surfaces fluctuate and ripple in a range of different scales. We discuss particle acceleration at rippled shocks in the presence of ambient solar-wind turbulence. This strongly affects particle acceleration and transport of energetic particles (both ions and electrons) at shock fronts. In particular, we point out that the effects of upstream turbulence is critical for understanding the variability of energetic particles at shocks. Moreover, the presence of pre-existing upstream turbulence significantly enhances the trapping near the shock of low-energy charged particles, including near the thermal energy of the incident plasma, even when the shock propagates normal to the average magnetic field. Pre-existing turbulence, always present in space plasmas, provides a means for the efficient acceleration of low-energy particles and overcoming the well known injection problem at shocks.