Effects of the radial electric field on the confinement of fast ions in ITER

The effects of a radial electric field (EF) on the losses of alpha particles and neutral beam injection (NBI) fast ions in typical ITER operation scenarios for both error fields due to test blanket modules (TBMs) and toroidal field (TF) ripple were evaluated using an iterative method to execute an orbit-following Monte-Carlo code and a one-dimensional transport code. The EF effect on the loss of fast ions strongly depends on the operation scenario as well as on the error field. The electric field is very significant in the loss of fast ions in a 9MA ITER operation scenario with a higher safety factor and in the error field associated with TBMs. The EF effect in the error field of TF ripple is very small in any operation scenario. The electric field is much more significant for the loss of NBI fast ions than for that of alpha particles. The radial electric field changes the toroidal precession of fast ions and consequently alters their condition of resonance with the error field, which may account for the EF effect on the loss of fast ions in ITER with TBMs.