Radial and Axial Transport in Trap Sections with Helical Corrugation

Plasma outflow through helically corrugated mirrors is influenced by its E x B rotation due to friction between the trapped and passing particles. If the relative velocity of these populations exceeds the thermal velocity, the onset of the two-stream instability will make the friction effective even in weakly-collisional plasmas. This regime can be achieved by plasma biasing. The momentum transfer between the plasma and the magnetic corrugation is accompanied by radial drifts and currents. The radial pinch effect is shown to be proportional to the axial pressure gradient that is created by the helical mirror. However, it can be directed either to or from the axis, depending on the symmetry of the helix and the sign of biasing. Equations of the transport model are presented and analyzed.