Experiments on stochastic resonance near Hopf bifurcation in a non-magnetized plasma

Stochastic resonance phenomena have been studied in a non-magnetized plasma. A white Gaussian noise is externally applied to coherently interact with the intrinsic periodic driven force of the system. Signal-to-noise ratio is improved by external noise in the fixed-point region near a Hopf bifurcation of the system. The experimental results are consistent with the predictions given by one-dimensional stochastic resonance model for an over-damping bistable system. Hopf bifurcation is found to be caused by the variation of the potential barrier of the system