Reduced critical rotation for resistive-wall mode stabilization in a near-axisymmetric configuration.
Recent DIII-D experiments with reduced neutral beam torque and minimum nonaxisymmetric perturbations of the magnetic field show a significant reduction of the toroidal plasma rotation required for the stabilization of the resistive-wall mode (RWM) below the threshold values observed in experiments that apply nonaxisymmetric magnetic fields to slow the plasma rotation. A toroidal rotation frequency of less than 10 krad/s at the q=2 surface (measured with charge exchange recombination spectroscopy using C VI) corresponding to 0.3% of the inverse of the toroidal Alfvén time is sufficient to sustain the plasma pressure above the ideal MHD no-wall stability limit. The low-rotation threshold is found to be consistent with predictions by a kinetic model of RWM damping.
Reimerdes
H
H
Columbia University, New York, New York 10027, USA.
Garofalo
A M
AM
Jackson
G L
GL
Okabayashi
M
M
Strait
E J
EJ
Chu
M S
MS
In
Y
Y
La Haye
R J
RJ
Lanctot
M J
MJ
Liu
Y Q
YQ
Navratil
G A
GA
Solomon
W M
WM
Takahashi
H
H
Groebner
R J
RJ