Magnetohydrodynamic theory of plasma equilibrium and stability in stellarators: Survey of results

The main advantage of a stellarator is its capability of steady-state operation. It can be exploited as a reactor if stable plasma confinement can be achieved with β∼10%. Therefore, this limiting pressure value is a key factor in stellarator development. This paper contains a survey of current ideas on the magnetohydrodynamic equilibrium and stability properties of stellarators with sufficiently high pressure. Here, any system of nested toroidal magnetic surfaces generated by external currents is considered a stellarator. Systems produced by helical or equivalent windings, including torsatrons and heliotrons, will be called ordinary stellarators, in contrast to those with spatial axes. It is shown that adequate confinement can be achieved.