Momentum transport from tearing modes with shear flow

A theoretical and computational study of momentum transport from reconnection from tearing modes in the presence of sheared flow in a reversed field pinch has been performed. Momentum transport from single tearing modes in the linear and nonlinear regimes and transport from multiple tearing modes is studied. It is found that, whereas a single mode produces transport, a strong enhancement in transport arises from the nonlinear coupling of multiple modes. A single tearing mode, in the presence of equilibrium flow, produces momentum transport in the vicinity of the reconnection layer. This is demonstrated from quasilinear calculation of Maxwell and Reynolds stresses. However, nonlinear, resistive magnetohydrodynamics computation of the full, multimode nonlinear dynamics reveals an additional effect. In the presence of multiple tearing modes, nonlinear coupling strongly enhances the torques and broadens their radial width. The resulting transport from current-driven instability is much more rapid than classical viscous forces.