Rotation of dust vortex in a metal saw structure in dusty plasma

By designing a metal saw structure, both negative and positive rotations of dust vortices are obtained experimentally. With increasing gas pressure, the dust vortex undergoes different spatial distribution from dense dust cloud to dust void, then to dust chain. The transition between the negative and positive rotations of dust vortices is reversible and controllable by changing the gas pressure/input power. The underlying mechanism of this transition is preliminarily explored.