Design and construction of two biased electrodes and preliminary experiments on the Keda Torus eXperiment

Abstract The electromagnetic turbulence in reversed field pinch (RFP) plasmas exhibits three-dimensional characteristics. Suppression of this turbulence is crucial for enhancing plasma confinement, necessitating control over the electric field or the current profile. To this end, two sets of electrodes have been designed and installed on the Keda Torus eXperiment (KTX) RFP device to manipulate the edge electric field and the edge parallel current profile. Subsequently, the edge radial electric field and edge parallel current profile control experiments are conducted. In the edge radial electric field control experiments, the edge radial electric field is altered under bias, accompanied with an increase in the electron density and plasma duration. However, under bias, both electrostatic and magnetic fluctuations are enhanced. In the edge parallel current profile control experiments, the results indicate that bias modifies the edge parallel current profile locally, leading to a localized increase in the field reversal depth and electron density. Additionally, a reduction in magnetic fluctuations is observed within the reversed field enhanced region under bias, suggesting that the bias suppresses magnetic perturbations.