Large-banana-width effects in the thermalization of alpha-particles in JET

摘要

A time dependent 3D Fokker-Planck code has been developed modelling the velocity distribution of alpha -particles in JET. The code is fast and can be run as part of the routine shot analysis. It was develo0ped to assist the interpretation of Collective Thomson Scattering data. The velocity distribution of fusion born alpaha -particles in devices such as JET is generally anisotropic. For a typical JET equilibrium we study the anisotropy introduced by the drift orbit motion of the new-born alpha -particles and how the anisotropy changes as the particles slow down due to the collisional drag of electrons. Finally a comparison is made to the anisotopy expected in larger devices such as ITER.