Alfvén Eigenmodes mediate benign fast ion transport in ITER steady state scenario without microturbulence

We address the fusion product and beam injected ions confinement in the ITER steady-state (SS) scenario in the presence of low frequency Alfvén eigenmodes (AEs). A self-consistent Resonance Broadened Quasi-linear code RBQ is applied [1,2]. AEs are destabilized by MeV neutral beam ions and alphas, but the fast ion transport remains modest if only classical particle slowing down is assumed. A stability study of low-frequency AEs includes NOVA/NOVA-C, RBQ and the guiding-center code NUBEAM packages. AE linear stability addresses the effects of ion's finite orbit width and Larmor radius, thermal ion and electron Landau damping, trapped electron collisional, and radiative dampings. We have found around 40 unstable or marginally unstable AEs spanning toroidal mode numbers from 1 to 39. The subsequent QL simulations are supported by NOVA-C modeling which prepares the wave-particle interaction matrices of unstable AEs. The RBQ code evaluates the constants of motion diffusion coefficients of both fast ion species. Then the NUBEAM package is applied to evolve the fast ion distribution functions in the constant of motion space. We found that the classical EP confinement does not lead to strong fast ion losses. The strong dependence of fast ion relaxation on microturbulence, however, does not allow us to reliably predict the fast ion confinement in ITER advanced scenarios without quantitative predictions of turbulence levels.