A quantitative comparison between confined fast ion data and models from radio frequency heating experiments with the three ion scenarios at JET

An effective way to generate fast ions in a fusion plasma is by means of Ion Cyclotron Resonance Heating (ICRH). The most adopted scenario is the so called minority heating, where a minority species at a few percent level is added to the main bulk plasma and is accelerated by ICRH. A typical example is the heating of 3He ions in a bulk deuterium plasma, which has also been used to study the excitation of fast ion instabilities and their transport [1]. A new ICRH scenario for plasma heating and fast ion studies has been theoretically proposed and experimentally demonstrated at the JET and Alcator C-mod tokamaks [2]. It is based on optimizing the polarization of the wave at the resonance in the vicinity of the ion-ion hybrid layer. This can be accomplished in a 3 ion species plasma, where two bulk species determine the propagation properties of the wave and a third species, which is added at the per mille level, efficiently absorbs the power in the vicinity of the ion-ion hybrid layer. In this paper we present a first quantitative analysis of the data obtained in a recent experiment on 3 ion ICRH heating in a D- (3He)-H plasma at JET, where H and D, in the ratio of approximately 70:30, were the two bulk species required by the scenario and 3He was the species to accelerate (X[3He] 0:2?0:3%).