The theory of hydromagnetic stability of a tokamak plasma

The author considers the stability of a plasma with a fixed boundary in a toroidal column of circular cross-section under the usual tokamak conditions and shows the effect of the non-local nature of the associated harmonics coupled with the fundamental mode. It is demonstrated that the stability conditions deteriorate with a rise in the pressure gradient, and this proves the inadequacy of the earlier known local criteria, according to which there is no instability when q 2 > 1.