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Compressional and shear wakes in a two-dimensional dusty plasma crystal
Journal article   Peer reviewed

Compressional and shear wakes in a two-dimensional dusty plasma crystal

V Nosenko, J Goree, Z W Ma, D H E Dubin and A Piel
Physical review. E, Statistical, nonlinear, and soft matter physics, Vol.68(5 Pt 2), pp.056409-5640915
11/2003
DOI: 10.1103/PhysRevE.68.056409
PMID: 14682896

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Abstract

Wakes composed of compressional and shear waves were studied experimentally in a two-dimensional screened-Coulomb crystal. Highly charged microspheres suspended in a plasma settled in a horizontal monolayer and arranged in a triangular lattice with a repulsive interparticle potential. Wakes were excited by a moving spot of Ar+ laser light. Depending on the laser spot speed, compressional waves formed a Mach cone and multiple lateral or transverse wakes, similar to ship wakes on the water surface, due to a combination of acoustic and dispersive properties. Shear waves, however, formed only a Mach cone, due to their nearly acoustic, i.e., dispersionless character. The experimental results show agreement with a recently developed theory and with molecular dynamics simulations, which assume a binary Yukawa interparticle potential. A generally useful method is presented for calculating the real part of the dispersion relation of the compressional waves based on the analysis of the spatial structure of a phonon wake. Fitting the resulting dispersion relation provides an independent measure of the interparticle potential, parametrized by the screening parameter kappa and particle charge Q.

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