Shocks propagate in a 2D dusty plasma with less attenuation than that due to gas friction alone

TL;DR

This study demonstrates that shock waves in a 2D dusty plasma decay less than expected from gas friction alone, likely due to wake-driven instabilities that sustain wave amplitude.

Contribution

It provides experimental evidence that 2D dusty plasma shocks persist longer than predicted by gas damping, extending previous 3D findings to 2D systems.

Findings

Shock waves decay less than gas friction predicts

Out-of-plane displacements observed in 2D layer

Wake-driven instabilities may sustain wave amplitude

Abstract

In a dusty plasma, an impulsively generated shock, i.e., blast wave, was observed to decay less than would be expected due to gas friction alone. In the experiment, a single layer of microparticles was levitated in a radio-frequency glow-discharge plasma. In this layer, the microparticles were self-organized as a 2D solid-like strongly coupled plasma, which was perturbed by the piston-like mechanical movement of a wire. To excite a blast wave, the wire's motion was abruptly stopped, so that the input of mechanical energy ceased at a known time. It was seen that, as it propagated across the layer, the blast wave's amplitude persisted with little decay. This result extends similar findings, in previous experiments with 3D microparticle clouds, to the case of 2D clouds. In our cloud, out-of-plane displacements were observed, lending support to the possibility that an instability, driven by wakes in the ion flow, provides energy that sustains the blast wave's amplitude, despite the presence of gas damping.