Speaker
Description
We present a reduced framework to describe the multiscale interaction between thermal plasma microturbulence, energetic particles generated by auxiliary heating, and the macroscopic instabilities that these particles can drive. Our approach focuses on how microturbulence regulates the saturation amplitude of energetic-particle-driven modes, such as shear Alfvén waves, through scattering-dominated nonlinear dynamics, where effective particle scattering balances wave dissipation. At the same time, energetic-particle-driven modes can modify the underlying microturbulence via nonlinear couplings and zonal mode excitation, introducing a feedback loop that can reduce turbulence levels and, in turn, lower the mode saturation amplitude. This interplay may lead to improved thermal plasma confinement and reduced energetic particle transport. The proposed framework provides a tractable way to capture the essential physics of this coupled system and to explore the mutual interaction between turbulence, energetic particles, and macroscopic instabilities.