Magnetohydrodynamic Stability of a Sharp Boundary Toroidal Plasma

In the toroidal coordinates, a stability analysis is presented for a toroidally symmetrical, sharp boundary plasma. The beta ratio β and aspect ratio, R p / r p , are assumed to be arbitrary. In the equilibrium, the maximum poloidal beta ratio β p is evaluated as Max β p =1/2 ( R p / r p +1). For the kink mode, Curves of β vs a safety factor q and curves of β p vs β in the marginal stability are described for the several aspect rations. Both curves show that the stable region for a fat plasma is wider than for a slender one. The curve of β vs q depends on the aspect ratio even at β=0, and the plasma is unstable for all values of q , if a value of β exceeds a critical value.