Dynamic behaviors of dust particles in the plasma-sheath boundary

A variety of dynamic behaviors in dusty plasmas is expected under the exper imental condition of weak friction with gas molecules. The device "KAGEROU" provides such an environment for dynamic collective phenomena. Self-excite d dust oscillations in Coulomb crystals have been observed at low values of plasma density and gas pressure. An instability mechanism was identified t o be delayed charging in an inhomogeneous equilibrium dust charge in the sh eath. The theoretical growth rate was formulated in relation to the destabi lization of a transverse dust lattice wave (T-DLW), which was found to be v ery sensitive to the presence of a small amount of hot electrons which prod uces a substantial positive equilibrium charge gradient delQ(d-eq) around t he equilibrium position of dust particles in the plasma-sheath boundary. Th e first experimental observation of a correlated self-excited vertical osci llations in a one-dimensional dust chain indicates a destabilization of T-D LW. The experimental condition is very consistent with the parameter area w hich predicts numerically an instability of T-DLW. (C) 2001 American Instit ute of Physics.