The phonon wake behind a charge moving relative to a 2D plasma crystal

In a recent experiment a wake was created in a 2D lattice of charged dust g rains by a charge moving parallel to the lattice plane. Multiple "Mach cone s" were observed in the wake. This paper describes a linear theory of the p honon wake caused by a charge moving relative to a crystalline lattice. The theory predicts multiple structures in the wake that match those observed in the experiments. These structures ale caused by constructive interferenc e of compressional phonons excited by the moving charge, combined with the strongly dispersive nature of these phonons. The theoretical wake is matche d to an experimental wake in order to determine the plasma Debye length and the charge on the dust grains.