Use of an m=2, n=1 static error field correction coil, (open quotes)The C-coil,(close quotes) on DIII-D to avoid disruptive locked modes

摘要

Minimizing resonant, static n = 1 error field with a phase steerable correction coil the C-coil, in DIII-D allows avoidance of disruptive locked modes. Alternatiely, increasing n = 1 error field in rapidly rotating plasmas can induce magnetic braking of rotation without locking for the study of the role of rotation on stability. Small toroidally asymmetric m = 2, n = 1 static field errors are of concern for the design of next-generation devices and for the operation of existing tokamaks. In low density ohmic plasmas for example, the torque of a small resonant error at the q = 2 surface can overcome the plasma inertial and/or viscous forces, stop the rotation and produce a large island which can cause disruption.