Relaxation of energetic particles distribution in NUBEAM due to the multitude of Alfvenic oscillations

In this research, the EP relaxation in the presence of multiple Alfvenic

oscillations is simulated in burning plasma ITER conditions. We

utilize a numerical scheme to map 2D diffusion and convection

coefficients for energetic particle transport in energy and minor

radius to the constant of motion (COM) space. The diffusion/convection

kick steps are chosen to allow the sufficient diffusion over the time

longer than the characteristic resonant EP motion in the island. Steady state ITER scenario with a strongly reversed

q-profile is analyzed. The ideal MHD code NOVA is used to analyze stability of Alfvén Eigenmodes (AE). In the presence of fusion alphas, 12 unstable

AEs were found out of 600 AEs.The RBQ code is used to compute EP diffusion

Coefficients for these 12 unstable AEs with delta B/B = 10^-3 - 10^-2.

These diffusion and convection coefficients are used in NUBEAM to simulate the overall EP transport.