Structure of fluctuations in the floating potential and ion saturation current in the edge plasma of the L-2M stellarator

Results are presented from the measurements of the ion saturation current, the floating potential, and their fluctuations in the edge plasma of the L-2M stellarator. Distinguishing features in the distribution of the ion saturation current and the floating potential near the separatrix are revealed and examined. Based on the cross correlation measurements with probes positioned at different toroidal angles, it is concluded that fluctuations in the ion saturation current are related to fast vertical displacements of the plasma column, whereas fluctuations in the floating potential have the form of waves propagating in the radial direction.