Mode coupling trigger of neoclassical magnetohydrodynamic tearing modes in tokamaks
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.
- Research Organization:
- Wisconsin Univ., Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER53218
- OSTI ID:
- 501485
- Report Number(s):
- UW-CPTC--97-6; ON: DE97007257
- Country of Publication:
- United States
- Language:
- English
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