He++ transport in the PDX tokamak

A powerful new approach to the study of particle transport and helium ash confinement in high-temperature fusion plasmas is demonstrated by charge-exchange recombination spectroscopy of He++ in ohmically heated PDX discharges. Time and space resolved measurements of He++ density following a short puff of helium gas into the plasma edge are fitted using a diffusive/convective transport model with coefficients D = (2.1 +- 0.9) x 104 cm2 s-1 and v(r)/D = (0.8 +- 0.3) delta (ln n/sub e/)/deltar