Ideal low-n and Mercier mode stability boundaries for /ell/ = 2 torsatrons
We studied the relationship between the stability properties of ideal low-n-internal modes and the three-dimensional (3-D) ideal Mercier criterion for /ell/ = 2 torsatron configurations. For the low-n stability studies, we used the stellarator expansion as implemented in the FAR code. The 3-D Mercier criterion was applied to equilibria calculated with the VMEC code. We found that low-n modes with singular surfaces lying in a Mercier region are, in general, unstable and the critical beta given by the Mercier criterion agrees well with the critical beta for the lowest-n unstable mode. This is verified even in the case of global n = 1 modes. Therefore, the 3-D Mercier criterion is a useful guide in mapping the ideal stability beta limits for these torsatron configurations. 5 refs., 5 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6164916
- Report Number(s):
- CONF-890403-1; ON: DE89010837
- Country of Publication:
- United States
- Language:
- English
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