A localized elastic deformation in the plane of a 2D plasma crystal is generated by a short laser pulse. The perturbed region simultaneously radiates compressional and shear waves. The decomposition of the complex wave pattern into the fundamental wave types is achieved by calculating the divergence and vorticity of the instantaneous vector velocity map. The shear waves form two vortex-antivortex pairs, which are known as the lowest modes of excitation in finite Yukawa clusters. The higher dispersion of the compressional waves leads to the formation of a wave train. The angular intensity distribution of the two wave types corresponds to two orthogonal dipole sources. Molecular dynamics simulations closely confirm these experimental results.
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