Charge-exchange measurements of the radial profiles of parallel and anti-parallel ion energy distributions on ATC

This paper describes charge-exchange measurements of the radial profiles of the ion energy distribution in the range of 600–2200 eV, both parallel and anti-parallel to the plasma current in the ATC tokamak. The measurements were made using a single-energy-channel multi-sight-line neutral-particle detector. The anti-parallel “temperature” profile was found to be parabolic or somewhat broader, in accordance with expectation, while the parallel “temperature” profile was nearly flat from the plasma centre to within a few centimetres of the edge. This difference between the two profiles is tentatively interpreted as being due to neoclassical effects associated with large banana orbits.