Shear flow effect on ion temperature gradient vortices in plasmas with sheared magnetic field

The effect of velocity shear on ion temperature gradient (ITG) driven vorti ces in a nonuniform plasma in a curved, sheared magnetic field is investiga ted. In absence of parallel ion dynamics, vortex solutions for the ITG mode are studied analytically. It is shown that under certain conditions the co upled equations for potential and pressure exhibit special tripolar vortex- like structures. For the general case, however, parallel ion dynamics is in cluded and the equation describing the stationary ITG vortex has the struct ure of a nonlinear Poisson-type equation. Analytical as well as numerical s olutions of this equation are presented for various possible cases. It is s hown that, for a critical value of the velocity shear asymmetric dipolar vo rtices can arise which are strongly modified as a localized vortex chain at resonance. For strong velocity shear these structures are destroyed and ul timately lead to a dominating monopolar form. The effects of magnetic shear indicate it may destroy these structures. (C) 1999 American Institute of P hysics. [S1070-664X(99)00108-1].