Collisionless Shocks Mediated by Shear-Flow Magnetic Fields in Ultraintense-Laser-Produced Counter-Streaming Plasmas

TL;DR

This paper demonstrates that shear-flow magnetic fields generated by ion-Weibel instability can efficiently mediate collisionless shock formation in ultraintense-laser-produced plasmas, significantly reducing the energy and time needed for experimental realization.

Contribution

It introduces a novel mechanism for collisionless shock formation via shear-flow ion-Weibel instability, with analytical scaling laws linking magnetic fields to laser intensity.

Findings

Magnetic fields generated by shear-flow ion-Weibel instability mediate shock formation.

The proposed mechanism reduces shock formation time and laser energy requirements.

Feasibility of producing collisionless shocks with existing laser facilities is demonstrated.

Abstract

The formation of ion-Weibel-mediated collisionless shocks (IW-CSs) in ultraintense-laser-produced counter-streaming plasmas is investigated using particle-in-cell simulations. Analysis of the underlying microphysics reveals that a shear-flow ion-Weibel instability generates magnetic fields, which isotropize the incoming flow and mediate shock formation. An analytical expression for the shear-flow magnetic field is derived, and a scaling law relating the magnetic field amplitude to the laser intensity is established. This mechanism reduces the shock formation time and the required laser energy by three and two orders of magnitude, respectively, compared to high-power laser experiments, making it feasible to produce IW-CSs using existing multi-kilojoule, picosecond ultraintense laser facilities.