THE PLASMA POTENTIAL ASYMMETRY AND STEADY-STATE RADIAL CONVECTION IN THE TEXT-U TOKAMAK

Asymmetries of various plasma parameters, both equilibrium and fluctua ting, are studied in the edge of the TEXT-U plasma using multiple Lang muir probe arrays. A substantial up-down asymmetry in potential is fou nd, suggesting the related local radial steady state convection could be significant. However, the dependence of this asymmetry on density s uggests that its flux surface average is not important except at low d ensities. Results during electrode biasing experiments, in which impro ved confinement is observed at low density, support this view.