Nonambipolarity of fluctuation-driven fluxes and its effect on the radial electric field.

ABSTRACT

The nonambipolarity of the fluctuation-driven particle transport is demonstrated experimentally. Convective radial transport of electrons by fluctuations is found to be significantly stronger than that of ions, leading to a mean fluctuation-driven radial current balanced in steady state by other bipolar particle losses. Fluctuation suppression leads to a sudden disappearance of this current and results in significant modification to the radial electric field. The observed change in the electric field is in good agreement with the measured fluctuation-driven flux.