The JET neutron emission profile monitor was used to study ohmically heated deuterium discharges. The radial profile of the neutron emissivity is deduced from the line-integral data. The profiles of ion temperature, Ti, and ion thermal diffusivity, chi i, are derived under steady-state conditions. The inferred chi i, for 0.3 < p = r/a < 0.5, is in the range 0.5-2.5m2s-1. The ion thermal diffusivity is higher than, and its scaling with plasma current opposite to, that predicted by neoclassical theory.
Measurement of local ion diffusion coefficients in the Tokamak Fusion Test Reactor