Suppression of ion-scale turbulent transport by MeV-range fast ions at JET

The success of ITER and future fusion power plants crucially relies on reaching self-sustained burning plasma conditions through fusion-born alpha particle heating. Therefore, it is of paramount importance to demonstrate that the achieved thermal energy confinement is sufficient to gen- erate enough alpha particles and subsequently that those alpha particles at very high energy (3.5 MeV) are well confined to self-sustain the total reaction. Nevertheless, the physics of alpha particles is complex and the extrapolation from present knowledge not straightforward. Fur- thermore, the strong gradients in tokamak plasmas add an extra ingredient: the microturbulence which, other than limiting the overall performance of the device, may interact with the confine- ment of the highly energetic alpha particles leading to unexpected regimes. It is thus essential to explore experimental scenarios mimicking ITER conditions in order to gain deeper insights on the mutual interaction between alpha particles and microturbulence.