The plasma potential asymmetry and steady state radial convection in the TEXT-U tokamak

摘要

Asymmetries of various plasma parameters, both equilibrium and fluctuating, are studied in the edge of the TEXT-U plasma using multiple Langmuir probe arrays. A substantial up-down asymmetry in potential is found, suggesting the related local radial steady state convection could be significant. However, the dependence of this asymmetry on density suggests that its flux surface average is not important except at low densities. Results during electrode biasing experiments, in which improved confinement is observed at low density, support this view