Self-consistent Langevin theory of self-excited oscillations of grains in plasma sheaths

Strong kinetic heating of grains is frequently associated with a melting transition in plasma crystals. At high pressures, above 100 mTorr, the melting transition is preceded by a vibrational phase whereas at low pressures, below 50 mTorr, observed large amplitude self-excited oscillations can lead to lattice disruption. At such low background gas pressures, only single layer crystals are formed. This work focuses on the low pressure regime and provides a theory of the self-excited oscillations which explains both the pressure and the power dependence of these oscillations as well as their threshold behavior. The implications for the melting transition are pointed out. (C) 2004 American Institute of Physics.