ELECTRIC FIELD STUDY WITH HIBP IN OH AND ECRH PLASMAS ON THE T-10 TOKAMAK

The plasma potential φ and radial electric field Er were studied on T-10 in a wide range of ohmic and ECRH regimes. At densities ne> 10 m, the potential has negative sign over the whole plasma cross section. At lower densities, the outer zone with positive φ and Er is formed. The absolute value of potential at mid-radius grows with density up to ne ≈ 3×10 m and then saturates. In regimes with ECR heating, ⎜φ⎟ decreases owing to the density pump-out and the electron temperature increase. Measurements of Er are compared with numerical simulations with several codes including nonambipolar fluxes due to the toroidal field ripple. The change of radially averaged ⎯Er with density and temperature qualitatively agrees with neoclassical expectations. PACS: 52.35.Mw, 52.55.Fa