Wave-Particle Resonances and Redistribution/Losses of Fast Ions in Tokamaks

Enhanced fast ion losses, mostly in the range of energies from around 1.2MeV to 2.4MeV, were measured during the activity of tornado modes in the JET tokamak. In this paper, a mechanism that explains the loss of fast ions triggered by core-localized tornado modes is proposed. This mechanism is based on the combined effect of the tornado modes and TAE (Toroidal Alfvén Eigenmodes) over the fast ions, with the tornado modes transporting the fast ions from the centre of the plasma to a region where tornado modes and TAE coexist and the TAE transporting then convectively the fast ions, most efficiently through the first bounce resonances (p = 1), all the way to the plasma edge. This mechanism of loss is in consonance with the experimental observations and it allows predicting accurately the energies at which most losses occur.
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