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 flow has a lead of about 20μs to the formation of E_r. These observations suggest that a radial current, responding to an induced voltage on the electrode, drives a poloidal flow which in turn drives the radial electric field.