Laser-experiments on particle interactions in strongly coupled dusty plasma crystals

Experimental investigations on the interaction between the dust particles in strongly coupled colloidal plasmas by means of laser manipulation are presented. In laboratory experiments, the particles are trapped in the nonequilibrium sheath environment, where gravity and the electric field introduce a preferred vertical direction. Thus, in the horizontal plane a repulsive Yukawa type interaction is found with a screening length of the order of the interparticle distance, whereas in the vertical direction wakefield attraction and nonreciprocal forces have been measured.