Effects of collisions and ( r , q ) distributions on shear-driven instability in dusty plasma

The Kelvin–Helmholtz instability (KHI) is examined by using a linear fluid model in a magnetized dusty plasma where ions follow the Boltzmann response and electrons follow a non-Maxwellian (r,q) distribution. A dispersion relation, including the effects of velocity shear, collisions, density gradient and wave propagation, is derived. The analysis presents that the KHI is mainly driven by shear flow. Density inhomogeneity and collisions make the instability more difficult to trigger and reduce its growth, and oblique propagation lessens the coupling between the wave and the shear flow. The growth rate reaches a maximum at an intermediate wave number. In comparison, the temperature ratio, ion-to-dust density ratio, and the nonthermal parameters only result in small changes and do not modify the overall behavior. These results suggest that the fundamental mechanism of KHI remains very stable even in non-equilibrium plasmas. The findings may help in understanding plasma mixing and transport in space environments and laboratory dusty plasma experiments where non-Maxwellian effects are common.