Overview of tokamak turbulence stabilization by fast ions

Tokamak experiments and modelling have in recent years increasingly indicated that the interaction between suprathermal (fast) ions and thermal plasma can lead to a reduction of turbulence and improvement of confinement. The regimes in which this stabilization occurs are of relevance to burning plasmas, and their understanding will inform reactor scenario optimization. This review summarizes observations, simulations, theoretical understanding, and open questions on this emerging topic.