Possibility of deterministic chaos in plasma wave interactions pumped by powerful radio waves in the ionosphere

Laboratory experiments with magnetically confined plasmas have established a link between exponential frequency dependence in power spectra of fluctuations and deterministic chaos in the underlying signal time series. The exponential frequency spectra are a feature of temporal pulses of Lorentzian shape, rather than for example resulting from a statistical property of the fluctuations. Exponential frequency spectra have now been identified also in stimulated electromagnetic emissions (SEE) from pumping of ionospheric F-region plasma by powerful radio waves transmitted from the ground. A model of wave interactions is outlined to interpret the observations. This involves ExB drifts due to wave modes localized in cylindrical density depletions. The results suggest the possibility of deterministic chaos in the pumped ionospheric plasma turbulence.