Shock width measured under liquid and solid conditions in a 2D dusty plasma

TL;DR

This study compares shock widths in a 2D dusty plasma under liquid and solid conditions, revealing narrower shocks in the liquid state, using high-resolution particle imaging techniques.

Contribution

It introduces a method to measure shock widths in dusty plasmas under different states, highlighting the influence of phase on shock characteristics.

Findings

Shock width is less in liquid than in solid conditions.

Shock width in solid is 4 to 6 lattice constants.

High-resolution imaging improves measurement accuracy.

Abstract

Widths of shocks are compared, under liquid and solid conditions, for a two-dimensional layer of charged microspheres levitated in a plasma. In this strongly coupled dusty plasma, a shock was launched as a blast wave by moving an exciter wire at a supersonic speed and then bringing it to a halt. Runs were repeated with the layer of microspheres prepared two ways: a crystalline-like solid, and a liquid. The liquid was sustained using laser heating, with conditions that were otherwise the same as in the solid. The shock width was found to be less in a liquid than in a solid, where it was 4 to 6 lattice constants. These measurements were based on the high-gradient region of density profiles. The profiles were obtained from particle coordinates, measured by high-speed video imaging. The spatial resolution was improved by combining particle coordinates, in the shock's frame of reference, from a sequence of images.