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.

• Received 18 November 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.5345