Analytical description of a neutral-induced tripole vortex in a plasma

An analytical description of a stationary triple vortex, observed in a cylindrical plasma, is presented. The concentration of neutrals, which is rather high in the experiment, turns out to be of crucial importance due to a spatially dependent distribution. In the radial direction the neutral concentration is paraboliclike, yielding an effective radial force directed towards the axis of the system. This neutral force causes the rotation of the plasma in the direction which is opposite to the E→xB drift. The stationary triple vortex develops for a starting Gaussian-density distribution and a rigid-body rotation of the plasma column