ELECTROMAGNETIC AND KINETIC EFFECTS ON THE ION TEMPERATURE-GRADIENT MODE

Effects of finite beta, ion kinetic damping and trapped electrons on the toroidal ion temperature gradient (ITG) mode have been investigated by two methods - a fully toroidal fluid analysis corrected for ion Landau damping, and an electromagnetic local kinetic dispersion relation. When trapped electrons are ignored, the ITG mode is stabilized at a beta value well below the critical beta for the ideal MHD ballooning mode (beta(MHD)). Trapped electrons are destabilizing and increase the upper limit of beta to a level comparable with beta(MHD). Ion Landau damping increases the critical temperature gradient typically by a factor of two (L(T)/L(B) less-than-or-similar-to 0.18), and the growth rate remains smaller than the ion transit frequency, omega(Ti) = k parallel-to V(Ti).