Alpha effect of Alfvén waves and current drive in reversed-field pinches

Circularly polarized Alfvén waves give rise to an α-dynamo effect that can be exploited to drive parallel current. In a "laminar" magnetic the effect is weak and does not give rise to significant currents for realistic parameters (e.g., in tokamaks). However, in reversed-field pinches (RFPs) in which magnetic field in the plasma core is stochastic, a significant enhancement of the α effect occurs. Estimates of this effect show that it may be a realistic method of current generation in the present-day RFP experiments and possibly also in future RFP-based fusion reactors.