Modifications of the edge electric field in the Compact Toroidal Hybrid torsatron with the use of a biased limiter

Sheared flows arising from spatially inhomogeneous, transverse electric fields are of interest in space, laboratory and fusion plasmas. In toroidal fusion plasmas, these flows are often associated with enhanced stability regimes. This presentation reports on recent experiments performed on the Compact Toroidal Hybrid (CTH) device (R = 0.75 m, a $\sim $ 0.2 m , B $\le $ 0.7, $n_e \quad \le \quad 10^{19} \quad m^{-3})$ in which a biased limiter inserted into the edge of the plasma is used to modify the edge radial electric field. Probe measurements indicate an asymmetric plasma response depending upon the sign of the bias. Probe measurements are also compared with interferometer measurements, which confirm the asymmetric plasma response.