Renormalized turbulence theory of ion pressure gradient driven drift modes

From the nonlinear gyrokinetic equation we formulate the renormalized turbulence equation for the ηi -mode drift wave instability. The study shows that the dominant nonlinear damping mechanism is from the E×B convection of the pressure fluctuation and that the kinetic modifications to the fluid E×B mode coupling, studied earlier, shift the spectrum toward the shorter wavelengths. Balancing the linear growth rate with the nonlinear damping rate at the linearly most unstable region, we calculate the anomalous ion thermal conductivity, which exceeds the neoclassical plateau formula and gives a value of the same order as that previously computed by Horton, Choi, and Tang [Phys. Fluids 26, 1077 (1981)], but with a kinetic enhancement factor. Also, the thermal conductivity formula remains finite for vanishing density gradient.