Coherent structures, transport and intermittency in a magnetized plasma

Two-dimensional coherent structures in potential and saturation current have been observed in the turbulent plasma of the simple magnetized torus Blaamann, using the conditional averaging technique. The structures observed in helium plasmas are evolving in time and rotating in the poloidal cross-section with a period of about 100 μs. The time resolved average radial particle transport generated by these structures has been calculated, and it is shown that large bursty flux events occur at the vortex separatrices whenever a double vortex in the potential is formed. The time evolution of fluxes has been correlated with the dynamical evolution of the structures and their topology. The results suggest that the intermittent behaviour of the transport is due to events involving the dynamics of coherent structures on a short-timescale. The observed structures are temporally intermittent. When they occur, they cover most of the plasma cross-section.