OBSERVATION OF ALPHA PARTICLES IN DT- AND T-PLASMAS ON JET
The fusion reaction between deuterium and tritium, D(T,n)4He is the main source of energy in future thermonuclear reactors. Charged fusion products of this reaction, α-particles (4He-ions), are born with an average energy of 3.5 MeV. Transferring energy to the thermal plasma during their slowing down, they should provide the self-sustained DT-plasma burn. 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 for the second DT-experiments (DTE2) on Joint European Tokamak (JET) to understand the main mechanisms of their slowing down, redistribution and losses and to develop optimal plasma scenarios. JET with the ITER-like wall (beryllium wall and tungsten divertor) and enhanced auxiliary heating systems produced significant population of α-particles and provided great opportunity to study the α-particle behaviour giving a stepladder approach for modelling and extrapolating to ITER. Several new results of α-particle studies in DTE2 will be presented in this paper.