Observation of alpha-particles in recent D-T experiments on JET
The fusion reaction between deuterium and tritium, D(T,n)4He is the main source of energy in future thermonuclear reactors. Alpha-particles (4He-ions) born with an average energy of 3.5MeV transferring energy to the thermal plasma during their slowing down, they should provide the self-sustained D-T plasma burn. The adequate confinement of α-particles is essential to provide efficient heating of the bulk plasma and steady burning of a reactor plasma. That is why the fusion-born α-particle studies have been a priority task in the second D-T experiments (DTE2) on JET to understand the main mechanisms of their slowing down, redistribution and losses developing optimal plasma scenarios. JET with the ITER-like wall (Be-wall and W-divertor), improved energetic-particle diagnostic capabilities and enhanced auxiliary heating systems producing significant population of α-particles provided possibility to study the α-particle behaviour. Selected results of α-particle measurements in DTE2 are presented in this paper giving an opportunity for modelling and extrapolating to ITER and burning plasma reactors.