Structure and melting of two-dimensional dust crystals

Dust particles in plasmas confined near the boundary between the plasma bulk and the sheath form a two-dimensional system when appropriate conditions are satisfied. To keep dust particles from running away horizontally, the electrostatic potential is usually applied to the electrode surrounding these dusty plasmas and we have finite two-dimensional systems of dust particles. Adopting the Yukawa model for the interaction between dust particles, structures of finite two-dimensional Yukawa systems at low temperatures have been analyzed both by molecular dynamics simulations and variational methods. The effect of the correlation energy between dust particles is shown to play an important role in the formation of the one-body distribution in these systems. Molecular dynamics simulations of large systems typically with 103 to 104 particles have been performed and the behavior of the mean square displacement is obtained for various combinations of characteristic parameters. The results are discussed in relation to the melting transition on the basis of the theoretical analysis on static structures.