Numerical study of anisotropic dust particles interaction in the PK-4 dusty plasma*

Dust particles in the PK-4 have been found to form extended filaments in the presence of a polarity-switched DC electric field. These filaments align with the externally applied electric field. Dust particles within the filaments become strongly coupled and behave as a crystalline-like medium parallel to the electric field (along the filaments). However, weaker coupling between filaments allows filamentary dusty plasmas to exhibit liquid-like behavior in the direction perpendicular to the electric field (i.e., across the filaments). Based on this, dusty plasmas can be used as a convenient analogue system to study phase transitions in smart materials, where the macroscopic size of the dust particles allows us to obtain visual information about the phenomenon. The different behavior along and across the filamentary structures indicates that the interaction between the dust grains in this state is highly anisotropic. Here the results from particle tracking analysis of data from the PK-4 microgravity experiments are compared with an N-body numerical model of the dust and plasma to describe the form of the interaction potential between dust grains as a function of the plasma parameters.