External control of the current profile in a reversed-field pinch (RFP), by means such as rf poloidal current drive, may have beneficial effects well beyond the direct reduction of Ohmic input power due to auxiliary heating. Reduction of magnetic turbulence associated with the dynamo, which drives poloidal current in a conventional RFP, may allow operation at lower density and higher electron temperature, for which rf current drive becomes efficient and the RFP operates in a more favorable regime on the n(tau) vs T diagram. Projected parameters for RFX at 2 MA are studied as a concrete example. If rf current drive allows RFX to operate with (beta) = 10% (plasma energy/magnetic energy) at low density (3 (times) 10(sup 19) m(sup (minus)3)) with classical resistivity (i.e. without dynamo-enhanced power input), 40 ms energy confinement times and 3 keV temperatures will result, matching the performance of tokamaks of similar size.
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