THERMALLY DRIVEN EDGE MAGNETIC TURBULENCE

As a model for the hot [beta(e)(L(s)/L(T))2 > 1] turbulent tokamak edge, the nonlinear saturated state of the high-beta(e) limit of microtearing turbulence is examined. This mode couples magnetic and electron temperature fluctuations. Using mixing length analysis and a variational calculation of the renormalized eigenmode equations, a magnetic fluctuation level and turbulent radial correlation length are derived. The resulting anomalous thermal diffusivity for auxiliary heating scales as T(e)7/4 n0(-3/2) I(p)-5/3 P(H)5/6 R7/3, where T(e) is the electron temperature, n0 is the density, I(p) is the toroidal plasma current, P(H) is the heating power, and R is the major radius.