Perturbated turbulent transport in a laboratory magnetoplasma: fluctuations, correlations and intermittency

The effects of an edge biasing potential on the intermittent behaviour of the anomalous flux in a cold toroidal magnetoplasma is studied at different radial positions in the poloidal plane. It is found that both the fluctuations and cross-correlations between particle density and radial velocity vary as a function of the applied bias potential, leading to a strong reduction of the flux at the plasma core. The reduction is due to a large extent to the conspicuous decorrelation between density and velocity signals, while the corresponding fluctuations are much less sensitive to the applied field. The study of intermittent bursts indicates that a strong increase in their mean waiting times takes place at the core