Instability and melting of a crystal of microscopic particles in a radio-frequency discharge plasma

The development of instability, heating, and melting of a two-layer crystal of dust particles in the sheath of a radio-frequency discharge has been studied by the method of Langevin molecular dynamics. The interaction forces between particles are determined in terms of a model developed earlier, in which the ion clouds under the upper particles are replaced by effective point charges. Both a pure Coulomb interaction and a screened interaction are considered. Various regimes of particle motion in the crystal are discussed. The experimental and calculated results for the mean energy of particles and the number of defects in the crystals are compared.