  The naturally persistent flow of hundreds of dust particles is experimentally
achieved in a dusty plasma system with the asymmetric sawteeth of gears on the
electrode. It is also demonstrated that the direction of the dust particle
flowcan be controlled by changing the plasma conditions of the gas pressure or
the plasma power. Numerical simulations of dust particles with the ion drag
inside the asymmetric sawteeth verify the experimental observations of the flow
rectification of dust particles. Both experiments and simulations suggest that
the asymmetric potential and the collective effect are the twokeys in this
dusty plasma ratchet.With the nonequilibrium ion drag, the dust flow along the
asymmetric orientation of this electric potential of the ratchet can be
reversed by changing the balance height of dust particles using different
plasma conditions.
