PLASMA CRYSTALS - STRUCTURE AND STABILITY

A collection of charged dust particulates interacting with electric fi elds in the sheath region of a low-temperature plasma is studied. Hami ltonian formalism shows that a wake potential is formed behind a movin g dust particulate when virtual phonons are exchanged between dust gra ins moving relative to the ambient plasma, while the wake potential va nishes if the dust grains are stationary with respect to the plasma. T he semi-classical Hamiltonian formulation is also applied to obtain di spersion relations for transverse and longitudinal oscillations associ ated with a linear chain of dust grains levitated in the balance of gr avitation and electric sheath field. Hydrodynamic effect on a circular lattice trapped in the wake potential suggests the stable polygon str ucture commonly observed as plasma crystals.