Turbulent Destabilization and Saturation of the Universal Drift Mode in a Sheared Magnetic Field

摘要

It is shown that turbulent diffusion of electrons across the rational surface, due to a combination of shear (delta k/sub parallel//delta r identical with k'/sub parallel/ not equal to 0) and random E Vector x B Vector fluctuations and/or stochastic magnetic perturbations, results in a finite amplitude-induced version of the absolute universal instability. Physically, the turbulent scattering of electrons across the rational layer leads to an effective finite value for k/sub parallel/ which destroys the stabilizing influence of the nonresonant electrons. At larger amplitudes, the electron growth is reduced and the ion shear damping is enhanced by spatial broadening of the mode, yielding nonlinear stabilization. (ERA citation 04:024965)