The Experimental Results of MHD Instability Suppression with Electrode Biasing in the HT-7 Tokamak

This paper presents the experimental results of magneto hydrodynamics (MHD) instability suppression in the HT-7 Tokamak by using electrode biasing. The biased voltage is applied between the electrode and the shell of the vacuum chamber. Three kinds of electrode biasing are used in the experiments and the effect on the MHD instability suppression is proportional to the current of the biased electrode. When positive voltage was applied to the electrode, we observed significant increases in the plasma electron density in the core area, extreme-ultraviolet bolometer emission and soft X-ray emission. Meanwhile the edge density is decreased. The plasma stored energy and the energy confinement time are increased with the biased voltage. Experimental results show that the biased voltage could help to suppress the MHD instability and to improve the gross global particle confinement in the HT-7 Tokamak.