Dynamics of a dust crystal with positive and negative dust

Abstract. A dust crystal consisting of charged dust grains of alternating charge sign (.../+/-/+/-/+/...) and mass is considered. Considering the equations of longitudinal motion, a linear dispersion relation is derived from first principles, and then analyzed. Two modes are obtained, including an acoustic mode and an inverse-dispersive optic-like one. The nonlinear aspects of longitudinal dust grain motion are also briefly addressed, via a Boussineq and Korteweg- de Vries description. Introduction. One of the most astonishing novel characteristics of dusty (complex) plasmas is the occurrence of strongly coupled dust configurations, such as the sponta-neous formation of crystalline-like periodic arrangements, in the sheath region (above the negative electrode) in gas discharge experiments. Crystal formation and dynamics have been studied in numerous experiments, in which ‘dust ’ particles were essentiall