EFFECT OF FINITE EPSILON-BETA-P ON THE ION TEMPERATURE-GRADIENT MODE IN A TOKAMAK

The ion temperature gradient (ITG) driven mode (or eta-i mode) is studied for a tokamak where the pressure gradient is sufficiently large (epsilon-beta-p approximately 1) to modify the local shear and the gradient of the magnetic field strength. It is found that these two diamagnetic modifications of the plasma equilibrium have a stabilizing effect on the ITG mode. This could contribute to the good edge confinement observed in the H-mode and the improvement of ion energy confinement in a second stability regime tokamak.