Magnetohydrodynamic Stability of a Sharp Boundary Toroidal Plasma

Abstract

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.