Plasma Crystal Melting: A Nonequilibrium Phase Transition

The plasma crystal is shown to exhibit a nonequilibrium two-step phase transition due to particle heating by ion streaming motion in the sheath. In a nonlinear model, the energy increase due to an ion induced instability is found to be separated from the melting transition. The plasma crystal melts at a much higher particle energy than expected from classical models. This behavior is explained by preferred destabilization of short-wavelength modes in the plasma crystal.