ELM-like activity has been recently observed in TJ-II, in plasmas withstored energy above 1 kJ. The plasma is observed to develop bursts ofmagnetic activity (seen in Mirnov coil signals) which are followed bya large and distinct spike in the Hα signal. An increase inelectrostatic and magnetic fluctuations at the plasma edge and a coldpulse towards the plasma centre are also characteristics of theseevents. In addition, the electron temperature profile locally flattensat the plasma radius where the temperature is in the range 100-200 eV. This flattening can be explained in terms of enhanced electronheat conductivity. Between ELM-like events the electromagneticturbulence at the edge decreases and the Te profiles recover theirformer shapes. This activity is probably triggered by a resonant m = 2, n = 3 mode.
Edge characteristics and global confinement of electron cyclotronresonance heated plasmas in the TJ-II Stellarator