Plasma and mode rotations in a reversed-field pinch device, TPE-1RM20

In a reversed-field pinch (RFP) device, TPE-1RM20, the rotation velocities of impurity ions and the magnetic modes are studied in connection to their roles on the dynamo activities. It is observed that the deceleration of the plasma poloidal rotation synchronizes with the deceleration of both poloid al and toroidal mode rotations at a discrete dynamo event. It is shown that the plasma poloidal rotation velocity in the case of high-Theta discharges becomes faster than that in the case of low-Theta discharges (Theta; pinch parameter). The radial electric field is estimated to be positive around r /a similar to 0.52 under some assumptions. Measurements reveal that the pla sma poloidal rotation is in the electron diamagnetic direction around r/a s imilar to 0.52. This indicates that the poloidal relation does not simply d epend on E-r x B flow. Through the present experimental results, some new s ubjects in the RFP plasma research are discussed.