Drift wave type turbulence spectrum in a sheared magnetic field

A theory of broad band turbulent spectra of drift wave type instabilities in a sheared magnetic field is developed. It is shown that different nonlinear processes are involved in determining the spectrum in different wave number ranges: nonlinear shear damping due to three wave resonant mode coupling, ion scattering of beat waves and a Hasegawa-Mima strong turbulence solution. Consequently, the spectrum consists of several appropriately matched subspectra. The presence of an energy sink due to nonlinear shear damping ensures the existence of steady state turbulent solutions. (author)