Resonant and non-resonant particle dynamics in Alfvén mode excitations

Shear Alfven wave excitations by energetic (E ≈ 1 MeV) ions in burning tokamak plasmas are investigated. The physical processes dominating resonant and non-resonant wave–particle interaction with fast ions are identified and discussed in various wavelength regimes. It is shown that both types of interactions depend crucially on the magnetic drift curvature coupling in conditions optimal for resonant mode excitation, which also correspond to maximized fast ion redistributions by collective oscillations. Energetic particle charge uncovering effects, viewed as (thermal) core component currents responding to the charge separation caused by large fast ion orbit widths, are further delineated in terms of the present results.