The nonlinear saturated state of the m=1, n=1 ideal MHD instability is calculated for a large-aspect-ratio tokamak. When the q(r) profile is nonmonotonic with q=qmin-1>0, the amplitude of the nonlinear state is given by 2qq=7.9[(qcq)32-1], where qc is the critical value of q at which the system is marginally stable. This nonlinear state is similar to that seen during the sawtooth crash in large tokamaks and may be related to the steady-state oscillations seen when sawteeth are suppressed by lower-hybrid current drive.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy