Absence of second stability in ATF
Ideal Mercier and ballooning modes for three-dimensional (3-D) equilibria of the Advanced Toroidal Facility (ATF) are studied in detail. These modes are found to introduce instability limits at modest beta values for pressure profiles for which previous results, based on a two-dimensional (2-D) equilibrium approximation, predicted the existence of a second stability region. This absence of second stability is in agreement with an analysis by Cooper et al. who used a simplified model for the ATF plasma boundary. The increased instability is found to result from the 3-D feature of the Pfirsch-Schlueter current. Furthermore, a strong quadrupole field is found to decrease the beta limit of these modes, contrary to the results obtained using the 2-D equilibria. Although direct comparison with measured beta values is not possible owing to the absence of profile data for ATF plasmas, pressure profiles used previously to model ATF data as well as in the 2-D analysis are used to obtain the results. The details of the pressure profiles and the plasma configurations strongly influence the stability limits on average beta which remains below 3%.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 132725
- Report Number(s):
- ORNL/TM-13040; ON: DE96002289; TRN: 96:000125
- Resource Relation:
- Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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