On the plasma pressure limit in stellarators

Recent results concerning the problems of critical plasma pressure in stellarators are reviewed. The authors emphasize that high equilibrium beta -values, obtained in a number of theoretical papers, are associated with the presence of a magnetic hill which makes these equilibria unstable in respect to the rigid body displacement of the plasma column. The authors indicate that the creation of a magnetic well or at least a decrease of the magnetic hill are desirable to increase the stability beta -limit.