Observation of neoclassical-like impurity transport in the q less than or equal to 1 region of the PBX tokamak

Charge-dependent convective impurity transport is observed in the central core of PBX H-mode discharges by measuring radial profiles for both low- and high-Z intrinsic impurities in the presence of strong sawtooth activity. Transport coefficients are derived by simulating the data with a diffusive/convective transport model which includes an internal disruption model. The time evolving Z/sub eff/ profile and central metallic densities are fitted during the quiescent phase between internal disruptions to yield a diffusion coefficient of D = 1 x 103 cm2/s for all species and an inward convective speed of v = 2.2 x 102 (r/a) cm/s for oxygen and carbon and v = 1.1 x 103 (r/a) cm/s for metals. These transport coefficients are in quantitative agreement with simple cylindrical neoclassical estimates for the region within q less than or equal to 1. 17 refs., 4 figs