Magnetohydrodynamic stability in a levitated dipole

Plasma confined by a magnetic dipole is stabilized, at low beta, by magneti c compressibility. The ideal magnetohydrodynamic (MHD) requirements for sta bility against interchange and high-n ballooning modes are derived at arbit rary beta for a fusion grade laboratory plasma confined by a levitated dipo le. A high beta MHD equilibrium is found numerically with a pressure profil e near marginal stability for interchange modes, a peak local beta of beta similar to 10, and volume averaged beta of <(beta)over bar>similar to 0.5. This equilibrium is demonstrated to be ballooning stable on all field lines . (C) 1999 American Institute of Physics. [S1070-664X(99)01809-1].