Poloidal divertor experiment with appliedE×B/B²drift

The × /B 2 drift arising from an externally applied electric field could be used in the divertor scrape-off zone of a tokamak or other toroidal device, either assisting or replacing a conventional magnetic field divertor. In an experiment in the Wisconsin Levitated Toroidal Octupole, operating with a relatively large toroidal magnetic field (q = 0.7), a radial electric field was applied in the scrape-off zone of a poloidal magnetic divertor. This reduced the plasma flux reaching the wall of the toroid by up to a factor of five beyond the effect of the magnetic divertor, in good agreement with a simple theoretical model. Plasma density and density scale-length were also reduced in the scrape-off zone, in qualitative agreement with the model, and with no detrimental effects on confinement of the central plasma.