Dynamics of ion temperature gradient modes in burning plasma conditions in the presence of energetic particles

Abstract We investigate the interaction between energetic particles (EPs) and ion temperature gradient (ITG) modes using the global gyrokinetic particle-in-cell ORB5 code. This work expands the parameter space to a broader range of EP temperatures, explicitly focusing on the burning plasma regime and introducing a wider variety of EP distribution functions. While we give confirmation that direct dispersion relation modification (DDRM) stabilizes ITG modes at intermediate EP temperatures, our results demonstrate that the dilution effect (DE) independent of temperature becomes dominant over DDRM in the burning plasma regime (T f > 50\,T i ). Furthermore, we extend our studies from Maxwellian distribution functions of EPs to more experimentally relevant distributions like slowing-down. To validate these findings for future reactor operations, we analyze an ITER pre-fusion operation scenario, comparing EP stabilization against electromagnetic and kinetic electron effects. In this context, EP stabilization is found to be weaker than electron Landau damping and β-stabilization. Overall, these results provide better understanding of EP-ITG interactions over a wider range of EP parameters relevant to burning plasma regime which is important for predicting turbulence and confinement in future devices such as ITER.