REDUCED MHD MODELLING OF TEARING MODE INTERACTIONS IN TOKAMAKS
A series of three dimensional reduced MHD simulations has been undertaken to investigate the nonlinear tearing mode interaction mechanism widely believed to explain hard disruptions in tokamaks. Validation of the computations has taken into account both linear and nonlinear numerical stability. Linear stability and energy conservation are shown to be necessary for convergence. Many features of simulations of "hard disruptions" bear out our theory of a spurious finite time singularity. Adjusting numerical and/or physical parameters suppresses the nonlinear instability as predicted, thus allowing calculations to be pursued indefinitely. The sensitivity of converged calculations to variations of number of modes, initial and boundary conditions has been studied. Mode interactions are insensitive to parameter variations; large amplitude tearing modes lead to transient Alfven wave bursts, with the persistence of the bursts being greater for fixed boundary voltage calculations.
Bibliographic Reference: WRITE TO THE LIBRARIAN, UKAEA, CULHAM LABORATORY, ABINGDON, OXON OX14 3DB (UK), MENTIONING REPORT CLM-P 779, 1986
Record Number: 1989125021700 / Last updated on: 1987-02-01
Available languages: en