Open AccessMode coupling trigger of neoclassical magnetohydrodynamic tearing modes in tokamaks
Author(s) -
T. A. Gianakon,
C. C. Hegna,
J. D. Callen
Publication year - 1997
Language(s) - English
Resource type - Reports
DOI - 10.2172/501485
Subject(s) - tearing , magnetohydrodynamic drive , physics , tokamak , toroid , magnetohydrodynamics , instability , coupling (piping) , nonlinear system , plasma , mode (computer interface) , ohm's law , rational surface , mechanics , quantum electrodynamics , nuclear physics , quantum mechanics , thermodynamics , mechanical engineering , computer science , engineering , operating system
Numerical studies of the nonlinear evolution of coupled magnetohydrodynamic - type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm`s law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise {Delta}{prime} stable, albeit once a threshold island width is exceeded. A possible mechanism for exceeding or eliminating this threshold condition is demonstrated based on mode coupling due to toroidicity with a pre-existing instability at the q = 1 surface