Electromagnetic and kinetic effects on the ion temperature gradient mode

Effects of finite β, 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 β value well below the critical β for the ideal MHD ballooning mode (βMHD). Trapped electrons are destabilizing and increase the upper limit of β to a level comparable with βMHD. Ion Landau damping increases the critical temperature gradient typically by a factor of two (LT/LB < or approx. 0.18), and the growth rate remains smaller than the ion transit frequency, ωTi = kparallelvTi. (author). Letter-to-the-editor. 16 refs, 2 figs