Abstract. Magnetohydrodynamic phenomena in the CT-6B tokamak based on Mirnov oscillations have been investigated by applying the limiter biasing potentials. The results show that setting up a radial electric field at the plasma edge could drive electromagnetic instabilities in the tokamak plasma. Magnetic oscillation frequency upon application of a positive biasing voltage decreases by about 10-15% and then after a delay time, t=2.5-3 ms, increases by about 20-25% with respect to their value without biasing. In the negative biasing regime, the oscillation frequency increases by about 10% in 1 ms after the application of the biasing pulse. The plasma poloidal rotation changes during two steps are related to its link with the radial electric field and the timescale of the density gradient change.