Inward turbulent transport produced by positively sheared radial electric field in stellarators

Inward turbulent particle transport observed in the rf heated plasma of the H-1 toroidal heliac is reproduced in the CHS heliotron/torsatron by genera ting a region of positive radial electric field shear (E-r' > 0) using elec tron cyclotron resonance heating of the plasma edge. Empirical condition of the radial reversal of the turbulent flux derived from two experiments ind icates that the shear electric held might be universally responsible for th e recorrelation of the density and plasma potential fluctuations leading to the inward transport.