Non-ambipolar transport in a magnetic divertor

Plasma transport is studied in a simulated magnetic divertor in the Wisconsin single-ring DC machine. The transport perpendicular and parallel to the magnetic field is shown to be non-ambipolar by a variety of measurements. The degree of the non-ambipolarity can be reduced by an appropriately designed divertor target plate, but not eliminated altogether. The density and temperature profiles in the scrape-off zone agree with the solutions of one-dimensional transport equations that assume classical cross-field diffusion due to ion-neutral collisions, classical cross-field conductivity due to electron-neutral collisions, and plasma flow parallel to the field at the local ion acoustic velocity. (author)