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The stability of the ion temperature gradient (ITG) mode in tokamak geometries is examined analytically for a non-monotonic q-profile [negative magnetic shear, (S)] for all ranges of wavelengths, short, intermediate and long. It is shown that the shear reversal has a weak stabilising intluence on the unstable mode [vi % qp, vi = (d In TJd In nJ]. Hence, the best way to stabilise these modes would be to optimise the equilibrium profiles so as to keep vi < qpdt and also S 6 0 in the plasma interior as envisioned by Rewoldt et al. [1993].

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