SCALING OF MAGNETIC TURBULENCE WITH LUNDQUIST NUMBER IN RELAXED STATEDEVICES

The scaling of magnetic turbulence with Lundquist number, (B) over til de(S), as generated by the dynamo in reversed-field pinches and sphero maks, is addressed. A theoretical framework is described, showing how the fluctuations arise from the dynamo and what dynamics determine the (B) over tilde(S) scaling. There are two limits of the dynamo. For a discrete (sawtoothing) dynamo, the time average of the magnetic fluctu ations is given by (B) over tilde proportional to S-0, but it is argue d that the averaged flux surface destroying magnetic field fluctuation s scale as (B) over tilde proportional to S--1/2. For a continuous dyn amo, with a steady-state saturated turbulent spectrum, the magnetic fi eld perturbations scale as (B) over tilde proportional to S--1/4. Prev ious theories of S scaling are reviewed. (C) 1996 American Institute o f Physics.