Effects of the magnetic curvature on the resistive interchange mode in tokamak plasmas

The reduced magneto-hydro-dynamical (MHD) equations show that the pressure gradient together with the magnetic-field curvature as a force drives the p lasma short-wavelength MHD instability in a toroidal system. This paper dis cusses the role of magnetic curvature of tokamak plasmas in some detail. It is found that the region of bad magnetic curvature is enlarged due to the presence of poloidal magnetic curvature. Especially, there exists a strong MHD instability in the upside or the downside of tokamak.