Potential structure of a plasma in an internal conductor device under the influence of a biased electrode

The present study examined the electric field structure in a magnetized plasma in a prototype ring trap (Proto-RT) device with an internal ring electrode. A radial electric field of up to 3 kV m −1 was produced in the broad region between the electrode and vessel wall when the ring electrode was negatively biased. The resultant E × B toroidal rotational speed is comparable to the ion sound speed. Positive biasing, however, created a gap between the plasma and the electrode, failing to produce an internal electric field.