The phonon wake behind a charge moving relative to a two-dimensional plasma crystal

In a recent experiment a wake was created in a two-dimensional lattice of charged dust grains by a charge moving parallel to the lattice plane. Multiple ‘‘Mach cones’’ were observed in the wake. This paper describes a linear theory of the phonon wake caused by a charge moving relative to a crystalline lattice. The theory predicts multiple structures in the wake that are qualitatively similar to those observed in the experiments. These structures are caused by constructive interference of compressional phonons excited by the moving charge, combined with the strongly dispersive nature of these phonons. © 2000 American Institute of Physics. @S1070-664X~00!04810-2#