Modelling of drift wave turbulence with a finite ion temperature gradient

With the use of consistent orderings in ε ∼ ρ s/a and δ ∼ kperpendicular ρs model equations are derived for the drift instabilities from the electrostatic two-fluid equations. The electrical resistivity η included in the system allows the dynamics of both the collisional drift wave instability (η not= 0) and the collisionless ion temperature gradient driven instability (ηnot= 0). The model equations also include effects of sheared velocity flows in the equilibrium plasma. The model equations used extensively in earlier nonlinear studies are obtained as appropriate limits of the model equations derived. The effects of electron temperature fluctuations are also discussed. (author)