Stability of local modes in low-aspect-ratio stellarators
The studies of MHD stability properties of stellarator-type configurations are complicated by the three-dimensional (3-D) nature of the equilibrium of these configurations. Usually, the unstable modes are pressure-driven and very localized around the rational surface. The 3-D Mercier stability criterion for local instabilities is therefore adequate for most of the stability studies. The method has been implemented in different 3-D equilibrium codes and is widely employed in stability calculations for stellarators. We use an average method based on vacuum flux coordinates to study the equilibrium of low-aspect-ratio configurations. The specific vacuum flux coordinates (/rho/,theta,/var phi/) are those described by Boozer. The radial variable is /rho/, while theta and /var phi/ are, respectively, poloidal and toroidal-like angles. The Jacobian is D = B/sub v//sup 2///rho/B/sub 0/g/sub B/. The only vacuum magnetic field covariant component different from zero is B/sub /var phi// = g/sub B/, while B/sub 0/..pi../rho//sup 2/ is the toroidal flux. 7 refs., 1 fig.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6179074
- Report Number(s):
- CONF-890302-17; ON: DE89008722; TRN: 89-009282
- Resource Relation:
- Conference: 16. European conference on controlled fusion and plasma physics, Venice, Italy, 13 Mar 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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