Measurements and implications of particle and momentum transport from magnetic stochasticity in MST

Magnetic stochasticity associated with radial magnetic field fluctuations ($\delta b_r )$ is expected to have significant effects on plasma transport. Particle and momentum transport due to stochastic magnetic fields are defined as $\frac{<\delta j_{//,e} \delta b_r >}{eB_0 }$ and $\frac{<\delta p_{//,i} \delta b_r >}{B_0 }$, respectively, where $\delta j_{//,e} $ and $\delta p_{//,i} $ are parallel electron current density fluctuations and parallel ion pressure fluctuations. A recently developed differential interferometer method is used to measure local density fluctuations, while a fast Faraday rotation diagnostic measures radial magnetic field fluctuations and current density fluctuations. Direct measurements of particle and momentum transport during reconnection events (the crash phase of a sawtooth oscillation) in the MST reversed field pinch show that; (1) the magnetic fluctuation-induced particle flux accounts for the change in the core equilibrium density, and (2) the convective component of the \textit{momentum} transport from stochasticity is of sufficient magnitude to contribute to the known anomalous momentum transport in the plasma core. Furthermore, the difference between magnetic fluctuation-induced electron flux and ion flux, ($\frac{<\delta j_{//} \delta b_r >}{eB_0 })$, has been experimentally determined by measuring Maxwell stress directly in the plasma core. It is nonzero (transport is locally nonambipolar) and produces a large radial electric field (and field shear) localized to the reconnection (resonant) surface. This electric field implies the existence of a localized \textit{zonal flow} that reverses direction about a reconnection surface -- a new mechanism for zonal flow generation. Author acknowledges contributions from D.L. Brower, B.H. Deng, T.F. Yates, UCLA, and the MST team. Work is supported by DoE and NSF.