Bondeson, A.Bussac, M. N.2008-04-162008-04-162008-04-16199210.1088/0029-5515/32/3/I13https://infoscience.epfl.ch/handle/20.500.14299/21216Stability limits for the ideal internal kink mode are calculated analytically for the Shafranov current profile using the large aspect ratio expansion. For equilibria with q(a) > 2 and circular cross-section, the maximum stable poloidal beta is below 0.1. In the absence of a conducting wall, an equilibrium with q(a) < 2 is unstable at arbitrarily small positive poloidal-beta or shear inside the q = 1 surface. The effects of non-circularity are discussed and quantitative results are given for elliptic cross-sections.text::journal::journal article::research article