Pressure gradient-driven modes in finite beta toroidal plasmas

When the ion temperature gradient is finite, the ideal kinetic theory plasma destabilizes the MHD mode below the critical beta of MHD theory. For a temperature gradient eta i>2/3 and inverse aspect ratio epsilon (Ti)<0.35 the electrostatic toroidal eta i-mode is unstable. The coupling between the two modes is investigated by solving the fourth-order system describing the shear Alfven-drift wave and the ion acoustic wave in the finite beta Tokamak. The ion kinetic velocity integral including the gyroradius effects and the ion magnetic drift resonances are used to obtain gamma k(k,q, beta , eta i,s, epsilon n,q, tau ) and gamma k/(kx2) for the modes. The study emphasizes the beta - and q-dependence of the transport associated with gamma k/(kx2).