By modulating the small gas feed required to maintain a steady-state Tokamak discharge a small density perturbation may be induced from whose propagation particle transport parameters may be adduced. Experiments in TEXT show that the phenomena may be adequately described by a simple model with constant diffusion plus inward convection except near the density limit. Diffusion coefficients and convective velocities has been determined for a broad range of hydrogen discharges and found to scale approximately as (nq)-1. The results are plausibly related to impurity transport parameters, thermal diffusivity, and particle confinement times. Diffusion coefficients for deuterium are systematically lower than for hydrogen.
Observation of enhanced ion particle transport in mixed H/D isotope plasmas on JET