Experimental evidence of mode coupling in drift wave intermittent turbulence using a wave number bicoherence analysis

Spatiotemporal mode coupling is studied experimentally in a cylindrical plasma device. For that purpose, a bicoherence analysis is applied to spatially resolved measurements of drift wave fluctuations in order to study nonlinear coupling in the wave number spectrum. The use of the k bicoherence is shown to be much more accurate and straightforward than one of the ω bicoherence, revealing bicoherence bursts with a characteristic duration shorter than the characteristic period of the signals. It is demonstrated that intermittent structures can be produced during these events