Observation of shear-wave Mach cones in a 2D dusty-plasma crystal.
Mach cones composed of shear waves were observed experimentally in a two-dimensional screened-Coulomb crystal. Highly charged microspheres suspended in a plasma and interacting with a repulsive Yukawa potential arranged themselves in a triangular lattice with hexagonal symmetry. Mach cones were excited by applying a force from the radiation pressure of a moving laser beam. They had a single-cone structure, which is explained by the almost dispersionless character of shear waves. The cone's opening angle obeyed the Mach-cone-angle relation. Results are compared to a molecular-dynamics simulation.
Nosenko
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V
Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242, USA. vnosenko@newton.physics.uiowa.edu
Goree
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J
Ma
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ZW
Piel
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A