Effect of the parallel current density on the local ideal 3-D MHD stability of the Helias configurationFunded under: FP3-FUSION 11C
The local ideal three dimensional magnetohydrodynamic (MHD) stability for the Wendelstein VII-X (W VII-X) configuration is studied. A volume averaged beta limit of 5 % is confirmed with a nearly optimal pressure profile using two methods to calculate the parallel current density: the magnetic method and the geometric method. It is shown that the ballooning stability does not depend on the method of calculating the parallel current. In contrast, the value of the Mercier criterion depends sensitively on which method is used. Not only is the geometric method not sensitive to resonant surfaces but there is a systematic error in the Mercier criterion for non-resonant surfaces when an insufficient number of modes is used to calculate the equilibria numerically with a spectral method. However, this systematic error does not change the averaged beta limit of W VII-X because the ballooning stability is more stringent than the Mercier stability for this configuration.
Bibliographic Reference: Article: Nuclear Fusion (Letters) Vol. 33 (1993) No. 12, pp. 1899-1904
Record Number: 199510308 / Last updated on: 1995-03-08
Original language: en
Available languages: en