TOROIDAL AND POLOIDAL PLASMA ROTATION IN THE REVERSED-FIELD PINCH RFX

In this paper, the toroidal and poloidal rotation velocities measured in the reversed field pinch device RFX from the Doppler shift of impur ity ion lines are presented and their relation with the (E x B)/B-2 pl asma velocity is discussed. It is found that the toroidal velocity at the edge has the opposite direction with respect to the core toroidal velocity, indicating a shear of the plasma rotation velocity of about 2 x 10(5) s(-1). Starting from the rotation measurements and the momen tum equation, a one-dimensional impurity diffusion model for the core plasma and a Monte Carlo code for the edge region are used to estimate the radial electric field, that is found to be around 1000-2000 V m(- 1) outward directed in the plasma core, and about 3000 V m(-1) inward directed at the edge, consistent with that measured at the edge by Lan gmuir probes.