Simulated study on trajectory losses of energetic alpha particles in ITER

Based on Monte Carlo method and collision-free model, the distributions and losses of energetic alpha particles in ITER plasma without magnetic perturbations and with magnetic perturbations are studied by using test particle simulation method. The results are as follows. In the absence of magnetic perturbations, the loss ratio of alpha particles is about 0.83%. The initial positions of these lost alpha particles are mainly located near the plasma boundary (the last closed flux surface). Under the condition of low frequency magnetic perturbations, with the increase of magnetic perturbed amplitude, the width of magnetic island increases, and the loss rate of energetic alpha particles increases correspondingly, but the loss rate is still relatively small (< 2%). Most of the lost energetic alpha particles fly in the direction of reverse plasma current, while most of them fly out of the plasma boundary in the direction of parallel plasma current, and almost all the lost alpha particles fly out from below the plasma equator. (authors)