Particle and Momentum Transport in a Stochastic Magnetic Field

3-D Resonant Magnetic Perturbations (RMP) have been successfully utilized to suppress or mitigate ELMS in tokamak plasmas. However, the mechanism for particle transport (density pumpout) and flow change in a stochastic magnetic field remains unclear. In the MST reversed field pinch (RFP), where a stochastic magnetic field is produced by multiple overlapping tearing modes, we observe a strong particle pump-out and parallel flow change similar to RMP experiments. Detailed measurements in the interior of the high-temperature RFP indicate that density fluctuations in a stochastic magnetic field play an important role both in particle and momentum transport. The particle flux primarily results from strong nonlinear mode coupling. A common physics basis for fluctuation-induced transport in the tokamak and RFP toroidal magnetic confinement configurations is explored. Work is supported by US DOE and NSF.