Prediction of energetic particle confinement in ITER operation scenarios

Energetic particle (EP) confinement properties of ITER operation scenarios have been comprehensively assessed using global gyrokinetic codes (GTC, CGYRO, ORB5), kinetic-MHD codes (FAR3D, GAM-solver, M3D-C1, MEGA, NOVA-C, XTOR-K), and reduced EP transport models (Kick, RBQ, TGLF-EP). These codes have been first verified and validated for simulations of EP transport in the DIII-D experiments. This collaborative research has been selected for US DOE FY2022 Theory Performance Target and adapted as the ITPA energetic particle joint activity B.11.12 project.

 

These large scale simulations find that macroscopic fishbone can be unstable in the ITER baseline scenario, but saturate at a low amplitude with insignificant distortion of flux surface and EP re-distribution. Various meso-scale Alfven eigenmodes (AE) saturate at high amplitudes and drive a large EP transport in the ITER steady state scenario, which results in a modest flattening of the EP profiles during the short simulation time. Strong microturbulence drives directly little EP transport but large thermal transport in both scenarios, which could affect EP transport driven by the AE and fishbone. These studies point to a modestly optimistic assessment of the EP confinement in the ITER, but also a significant relaxation of the alpha particle profile in the steady state scenario. Finally, integrated simulation of cross-scale coupling is needed to reliably predict EP confinement in the ITER, as demonstrated in the simulations of the DIII-D experiments.