Effects of magnetic shear on ion temperature gradient driven turbulence

Effects of magnetic shear in the tokamak is studied on the plasma transport due to ion temperature gradients. The work is motivated by the recent issues that the reversed configuration of the q profile enhances the plasma confinement. Fluid model in the slab geometry is employed and upper bound is computed on the heat transport for various q profiles, either positive or negative slopes and either positive or negative curvatures across the resonant surface. In order to obtain upper bound variational principle is applied with the constraint of energy conservation. Additional constraint on the parallel energy balance is included in order to account for the magnetic shear. Bounding curves of the heat flux versus ion temperature gradient are obtained through the computational solution of Lagrange equations. Comparison is made between the cases of different values of the shear and the curvature.