Magnetic and velocity shear effects on η<SUB>i</SUB>-modes in plasmas with ion temperature anisotropy

Ion temperature gradient (ITG or ηi) driven microinstabilities are studied, using fluid and kinetic theories, for plasmas with ion temperature and temperature gradient anisotropy. The sheared slab geometry model (nonlocal scheme) is employed. The effects of a parallel velocity shear and a perpendicular velocity shear on the modes are investigated. It is shown that the anisotropy in ion temperature gradient enhances (reduces) the stabilization from a magnetic shear for η⊥>η∥ (η⊥>η∥). An anisotropy of T⊥>T∥ in ion temperature is found to give an overall stabilizition (destabilization) for low (high) magnetic shear, ŝ∼0.1 (ŝ∼0.4). Parametric dependence of the instabilities is systematically analyzed. Previous results from the shearless toroidal model are confirmed with a sheared torus