Fast flow phenomena in the MST reversed-field pinch

摘要

We have obtained these key results from the MST RFP: (1) The toroidal velocity fluctuations of the plasma are coherent with the large-scale magnetic tearing modes; during a sawtooth event the scalar product of v(sub (phi)) and B(sub r) is similar to that expected for the MHD dynamo electromotive force. (2) Non-resonant external field errors do not cause magnetic mode locking. (3) Toroidal plasma flow closely tracks the toroidal rotation of the magnetic tearing modes, including the fast changes that occur during sawtooth and locking events. (4) The sawtooth change in mode rotation and plasma flow is not caused by external electromagnetic torque. (5) Plasma flow and mode rotation can be actively controlled, including rotation reversal and unlocking, by modifying E(sub r) with a biased probe or plasma source electrode.