Rotation of a multi-species plasma in a cylinder

The paper investigates the momentum balance of a multi-species plasma in a cylinder with helical magnetic field. The main magnetic field is oriented in the z-direction. Starting from the macroscopic equations, a steady-state solution is obtained which includes the effect of centrifugal forces and Coriolis forces. The poloidal rotation and axial flow of each particle species is governed by the balance between spin-up, viscous damping, turbulent forces and the v x B driving term. In cylindrical geometry, classical viscous effects are very small and can be easily dominated by the turbulent viscosity. The effect of turbulent Reynolds stresses and the turbulent viscosity is investigated. Under quite general assumptions about the dependence of the anomalous transport coefficients on the velocity shear, criteria on the existence of the bifurcation points and multiple solution can be formulated. The shaping of the velocity shear and the transport barrier depend strongly on the eddy viscosity. Numerical solutions of the differential equations for a two-component plasma support the analytical results. The viscosity is considered as a variable parameter simulating the effect of turbulent eddy viscosity. These computations will be compared with the experimental results found in the HDH-mode experiments in Wendelstein 7-AS