Core transport improvement during poloidal current drive in the RFX reversed field pinch

We describe plasma profiles evolution during pulsed poloidal current drive experiments performed with the RFX reversed field pinch device. With extern al drive of edge poloidal current, magnetic fluctuations are reduced sugges ting a concomitant reduction of the spontaneous dynamo action. The electron temperature profile is seen to peak in the plasma core, consistently with a reduction of the heat conductivity due to a substantial decrease of MHD d ynamo fluctuations. Our results also indicate that the magnetic turbulence due to these fluctuations, which dominates heat transport in the core of th e reverse field pinch configuration, does not drive an appreciable heat flu x at the edge. [S0031-9007(98)08371-9].