Drift-Wave Fluctuations and Anomalous Diffusion in a Fully Ionized Cesium Plasma

An experimentally determined diffusion coefficient is related to the amplitude of a continuum spectrum of drift-wave-like fluctuations. It is found that the diffusion coefficient depends upon the amplitude of the fluctuation in a way which is consistent with the nonlinear diffusion theory of Dupree; that is, D⊥ ∼ 〈δn2〉 for small amplitude and ∼ 〈δn2〉1/2 for large amplitude. An elementary model which predicts the relative fluctuation amplitude 〈δn2〉/n02 and the autocorrelation time of the continuum spectrum of driftlike waves is also presented and shown to be in agreement with both the properties of the observed spectrum and the results of the diffusion measurements.