Magnetically confined plasmas are often subject to relaxation oscillations accompanied by large transport events. This is particularly the case for the high confinement regime of tokamaks where these events are termed edge localized modes (ELMs). The
y result in the temporary breakdown of the high confinement and lead to high power loads on plasma facing components. Present theories of ELM generation rely on a combined effect of edge currents and the edge pressure gradient exceeding critical values which result in intermediate mode number ($n cong 10-15$) structures (emph{filaments}) localized in the perpendicular plane and extended along the field line. It is shown here by detailed localized measurements of the three components of the magnetic field perturbation carried by an individual type I ELM filament that these filaments carry a substantial current. The observations provide essential information for the understanding of ELM dynamics.
Edge turbulent structures are commonly observed in fusion devices and are generally believed to be responsible for confinement degradation. Among their origin Drift-Alfven turbulence is one of the most commonly suggested. Drift-Alfven paradigm allows
the existence of localized vortex-like structures observed also in various systems. Here we present the evidence of the presence of drift-Alfven vortices in the edge region of RFX-Mod RFP device, showing how these structures are responsible for electromagnetic turbulence at the edge and its intermittent nature.
