Changes in plasma potential and turbulent particle flux in the core plasma measured by heavy ion beam probe during L?H transitions in the TJ-II stellarator

Plasma potential and turbulent particle flux Gamma(ExB) in the plasma core were measured for the first time during L-H/H-L transitions in the TJ-II heliac using a heavy ion beam probe. The L-H transition is characterized by a simultaneous potential drop similar to-100V over the whole plasma radius, formation of density pedestal and a strong radial electric field E-r between -100 to -150 Vcm(-1) in the edge (0.8 < rho < 0.9), strong suppression of the broadband density and potential oscillations and of Gamma(ExB) in the edge and core plasma.