Dual-Electrode Biasing Experiments in KT5C Device

Based on the single biasing electrode experiments to optimize the confinement of plasma in the device of KT-5C tokamak, dual-biasing electrodes were inserted into the KT5C plasma for the first time to explore the enhancing effects of biasing and the mechanisms of the biasing. By means of applying different combinations of biasing voltages onto the dual electrodes, the changes of E r , which are the key factor for boosting up the E r × B flow shear, were observed. The time evolution showed that the inner electrode played a major role in dual-biasing, which drew larger current than the outer one. The outer electrode produced little influence. It turned out that the dual-biasing electrodes were as effective as a single one in improving the plasma confinement, for the mechanism of biasing was essentially an edge effect.