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 ( approximately 1.8 x 10(13) cm(-3)) in the HT-7 Ohmic discharges (where the plasma current I(p) is about 170 kA, loop voltage V(loop)=2-3 V, toroidal field B(T)=1.9 T, and Z(eff)=3-4). It is observed that an improved confinement mode characterized by D(alpha) 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.
Gao
X
X
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China. xgao@mail.ipp.ac.cn
Xie
J K
JK
Wan
Y X
YX
Ushigusa
K
K
Wan
B N
BN
Zhang
S Y
SY
Li
J
J
Kuang
G L
GL