Perturbations to deuterium and tritium distributions caused by close collisions with high-energy alpha-particles

The effect of nuclear elastic scattering (NES) of deuterium and tritium in close collisions with hot alpha-particles is considered. Calculations of the perturbed deuterium and tritium distribution functions are based on numerical solution of the three-dimensional trajectory averaged kinetic equation. The equation includes the full drift trajectory averaged Coulomb collision operator and the NES particle source. Modelling is carried out for parameters relevant to JET DT experiments and results of calculations are compared with typical measurements of NES deuterons. In addition, we evaluate the maximum achievable NES perturbation to the DT plasma. Finally, a potential opportunity for estimation of alpha-particle pitch-angle anisotropy, using measurements of NES perturbed deuterium or tritium distributions is discussed. We show that it is important to account for NES effects in order to accurately diagnose the alpha-particle distribution.