Investigations of attractors arising from the interaction of drift waves and potential relaxation instabilities

The nonlinear interaction between ion-drift waves and electrostatic potential relaxation instabilities (PRI) is studied in a magnetized double plasma with externally induced axial electron drift. The PRI is identified as unstable weak double layer which is determined by additional electron beam injection. The axial drift current Id is used as control parameter for the dynamical state of the plasma and shows a critical transition to anomalous resistivity. For various drift current values, time series of probe signal fluctuations have been recorded. The wave number and bispectral analysis is used to establish the interaction as nonresonant modulation of drift waves by PRI’s. The complexity of strongly nonlinear and fully turbulent regimes is investigated by statistical analysis of the reconstructed phase space. The nonlinear interaction is characterized by low correlation dimension values between 3≤D2≤5 and positive largest Lyapunov exponents. The results confirm earlier findings, which were obtained in a different device.