Fast-ion redistribution due to sawtooth crash in the TEXTOR tokamak measured by collective Thomson scattering

Here we present collective Thomson scattering measurements of 1D fast-ion velocity distribution functions in neutral beam heated TEXTOR plasmas with sawtooth oscillations. Up to 50% of the fast ions in the centre are redistributed as a consequence of a sawtooth crash. We resolve various directions to the magnetic field. The fast-ion distribution is found to be anisotropic as expected. For a resolved angle of 39¿ to the magnetic field we find a drop in the fast-ion distribution of 20–40%. For a resolved angle of 83¿ to the magnetic field the drop is no larger than 20%. (Some figures in this article are in colour only in the electronic version)