Drift-Wave Spectra Obtained from the Theory of Nonlinear Ion-Landau Damping in Sheared Magnetic Fields

Abstract

The local character, in poloidal mode-number space, of the resonant nonlinear interaction of drift waves with ions in a sheared magnetic field permits an analytical determination of the spectrum. Important processes underlying the stabilization are energy cascade and transfer, respectively, in close (${{k}_{\ensuremath{\theta}}}^{\ensuremath{'}}\ensuremath{\cong}{k}_{\ensuremath{\theta}}$) and distant (${{k}_{\ensuremath{\theta}}}^{\ensuremath{'}}{a}_{s}\ensuremath{\cong}\frac{1}{{k}_{\ensuremath{\theta}}{a}_{s}}$) interactions. The spectral index $n=4$ of the high-mode-number tail is independent of the excitation mechanism.