Shock width measured under liquid and solid conditions in a two-dimensional dusty plasma.

Anton Kananovich,J Goree

doi:10.1103/physreve.104.055201

Anton Kananovich, J Goree

Open Access

https://doi.org/10.1103/physreve.104.055201

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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 crystallinelike 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 four to six 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.

Highlights

For shocks in all kinds of substances, the structure of a shock and in particular its width have attracted scientific interest for many years [1,2,3,4,5,6,7,8]
There seems to be a paucity of experiments, which can be explained by the challenge of measuring a shock profile in conventional solids, liquids and gases, where shocks propagate at speeds of the order of 102 to 103 m/s, and a shock width can be as small as 10−10 m
These difficulties of high speed and microscopic thinness are avoided by experimenting with dusty plasmas, where typical shock speeds are of the order of centimeters per second, and shock widths have been observed to be of the order of millimeters [10,11,12]

Summary

INTRODUCTION

For shocks in all kinds of substances, the structure of a shock and in particular its width have attracted scientific interest for many years [1,2,3,4,5,6,7,8]. The video microscopy diagnostics that are commonly used for laboratory dusty plasmas allow the experimenter to observe the sample at the microscopic level, tracking individual particles, and making time-resolved in-situ measurement profiles of useful quantities, such as number density. These advantages have led to many studies in the literature for dusty plasmas [10, 11, 13,14,15,16,17,18,19,20,21,22].

APPARATUS AND EXPERIMENTAL CONDITIONS

ANALYSIS METHOD

Features of the density profile

CONCLUSIONS