Generation of radial electric field with electrode biasing

Time and space resolved measurements of the radial electric field (E-r) have been conducted during the electrode biasing experiments on the KT-5C tokamak. The suppression of the turbulent transport with the change of E-r induced by the biased electrode is observed. It is found that the poloidal flow contributes to the main part of the E-r, and the change of the poloidal how has a lead of about 20 mus to the formation of E-r. These observations suggest that a radial current, responding to an induced voltage on the electrode, drives a poloidal how which in turn drives the radial electric field.