Finger instability in radiatively driven dusty plasmas

In this work the dynamics of a three-fluid plasma consisting of electrons, ions and charged dust particles are considered. The plasma is illuminated b y a radiation field, which, through absorbtion, accelerates the dust partic les, By direct acid Coulomb collisions the gained momentum is partially tra nsmitted to electrons and ions. A steady state can be achieved by an extern al gravitational field acting against the radiation. After presenting the s teady-state flow, linear perturbations of dynamical variables with the wave vector perpendicular to the radiation flux are considered. A Linear analys is is performed by reducing the full three-fluid description to a suitable one-fluid system of equations, assuming the plasma to be quasineutral and o mitting plasma species separation. It is demonstrated that when the drag fo rce between ions and dust particles is a decreasing function of their relat ive velocity, the steady state is unstable against the formation of paralle l layered streams with high and low relative Row velocities, i.e., multiple current sheets. The temporal evolution of this instability is then investi gated by means of numerical simulations in the framework of a complete thre e-fluid model. (C) 2000 American Institute of Physics. [S1070-664X(00)01212 -X].