Nonlinear State of m=1 Instability in Tokamaks with Nonmonotonic q Profiles

Avinash, R. J. Hastie, J. B. Taylor, S. C. Cowley

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)2647-2649
Number of pages3
JournalPhysical review letters
Issue number23
StatePublished - 1987

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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