Stationary multifaceted asymmetric radiation from the edge and improved confinement mode in a superconducting tokamak

Stationary multifaceted asymmetric radiation from the edge (MARFE) is studied by gas-puffing feedback control according to an empirical MARFE critical density [formula presented] in the HT-7 Ohmic discharges (where the plasma current [formula presented] is about 170 kA, loop voltage [formula presented] toroidal field [formula presented] and [formula presented] It is observed that an improved confinement mode characterized by [formula presented] line emissions drops and the line-averaged density increase is triggered in the stationary MARFE discharges. The mode is not a symmetric “detachment” state, because the quasi-steady-state poloidally asymmetric radiation (e.g., C III line emissions) still exists. This phenomenon has not been predicted by the current MARFE theory.