Several Ion Cyclotron Resonance Heating (ICRH) schemes in DT plasma have been considered for the ITER reactor [1]. Most of these heating schemes are minority heating at fundamental frequency. In DT plasma, both reactants can also absorb RF power as majorities at fundamental n=1 or harmonic n=2 frequency. Understanding benefits of directly heating fusion reactants via RF waves is essential in optimising ITER fusion performance.
This work studies the impact of the ICRH heating of the fast ion populations of the main plasma species, D and T, on the fusion performance in recent JET DTE2 campaign. Evenly balanced DT mixture, D/T~0.5/0.5, was sustained in these experiments, while comparable sources of fast D and T ions were provided by the two Neutral Beam Injector (NBI) sources at JET. Minorities were deliberately not injected in order to study the clear impact of RF heating of the main reactants. The study focuses on experiments in which ICRH was tuned to provide either n=2 D or n=2 T central resonances for which fast NBI ions provide a good absorber. The effect of the ICRH power on D and T beam fast ion dynamics has been analysed with regard to fusion rates by means of TRANSP simulations. Moderate increase in reaction rates has been predicted and attributed to ICRH n=2 D and n=2 T heating of fast ions created by NBI. Contribution of various heating and fast ion sources have been assessed and discussed.
1. M. Schneider et al 2021 Nucl. Fusion 61 126058