LATTICE WAVES IN DUST PLASMA CRYSTALS

Techniques previously known from solid state physics are used to look at linear and weak non-linear wave propagation in dust lattices. These expansion techniques include only electrostatic interactions between neighbor particles in addition to assuming small vibrations in the dus t lattice. As a simple model for the dust lattice, a one-dimensional B ravais lattice is considered. For this particular lattice, expressions for the linear phase velocity are compared to a quasi-particle simula tion. The word quasi here means that only the dust particles are repre sented as diffuse objects, while the plasma is treated as a fluid. The simulation is also used to study the breakdown of the analytical theo ry and to investigate non-linear dust lattice waves. A very good agree ment is found between the analytical expressions and the particle simu lations, for cases where the average Just separation a is of the order of or larger than the plasma Debye length lambda(D). This is a condit ion which very often applies to dust crystal in laboratory experiments . Application of this wave theory is therefore discussed with respect to recent laboratory experiments where dust lattice waves are excited. (C) 1996 American Institute of Physics.