Long-range attractive and repulsive forces in a two-dimensional complex (dusty) plasma.

An interaction of a negatively biased wire with a monolayer lattice of negatively charged particles has been studied experimentally. The particles levitated at the height of the wire in a sheath of an rf discharge. It was found that the particles close to the wire were repelled from it electrostatically, while the far particles were attracted due to the drag of the ion flow deflected toward the wire. The ion drag force prevails far from the wire, whereas the electrostatic force is stronger close to the wire. The range of the forces is one to two orders of magnitude greater than the screening length.