The stability of the ion temperature gradient modes is investigated using the kinetic ion response without expansions in ω_D/ω. A systematic parameter study is carried out using a low‐beta circular flux surface equilibrium in order to determine the stability boundaries in η_i vs ε_n space (η_i=d ln T_i/ d ln n, ε_n=L_n/R). Particular attention is devoted to the consequences of the presence of these modes for anomalous ion transport.

We discuss the processes underlying the excitation of fishbone-like internal kink instabilities driven by supra-thermal electrons generated experimentally by different means: Electron Cyclotron Resonance Heating (ECRH) and by Lower Hybrid (LH) power injection. The peculiarity and interest of exciting these electron fishbones by ECRH only or by LH only is also analyzed. Not only the mode stability is explained, but also the transition between steady state nonlinear oscillations to bursting (almost regular) pulsations, as observed in FTU, is interpreted in terms of the LH power input. These results are directly relevant to the investigation of trapped alpha particle interactions with low-frequency MHD modes in burning plasmas: in fact, alpha particles in reactor relevant conditions are characterized by small dimensionless orbits, similarly to electrons; the trapped particle bounce averaged dynamics, meanwhile, depends on energy and not mass.

The toroidal semicollisional microinstabilties driven by trapped electron dynamics and ion temperature gradients are analyzed using kinetic theory. Analytic dispersion relations are derived and discussed, with particular attention to the modeling of anomalous electron and ion thermal conductivity. Relations with previously derived models of anomalous transport and experimentally observed trends of the global energy confinement time are also discussed.