“…An apparent confirmation of these theoretical conclusions was found on early experiments at the Tokamak Fusion Test Reactor (TFTR) [7][8][9][10], where an upper limit for fast ion diffusivities was found at 0.1 m 2 · s −1 , an order of magnitude smaller than that of thermal ions. Recently, however, there has been renewed interest, triggered by experimental observations of anomalous redistribution of NBI ions at the Axial Symmetric Divertor EXperiment (ASDEX) Upgrade [11,12], at the Joint European Torus (JET) [13,14], at the Mega-Ampere Spherical Tokamak (MAST) [15,16], and at DIII-D [17,18].…”