Ballooning modes in closed systems with a spatial magnetic axis

A comparative analysis of the stability of small-scale MHD modes, vi., Mercier modes, ideal ballooning modes and resistive ballooning electromagnetic modes is performed for torondal systems with a spatial magnetic axis. As a result, stability criteria are given, stabilization and destabilization mechanisms of the modes considered are indicated. It is shown that in traps with a complicated magnetic field geometry under currentless regime the critical plasma pressure, that determines βsub(THETA)sup(thr), when the plasma becomes stable, is different for the above-mentioned Modes and depends on characteristic properties of the trap under study. A ''fast'' dissipative mode appears to be most dangerous because it gets excited With plasma pressUre increase