Application of Quasi-Symmetry Concept to Conventional Stellarators

Quasi-symmetry condition, which demands that B² does not depend on one from two angles in Boozer coordinates, is analyzed for stellarators with planar circular axis. In stellarator approximation this condition is reduced here to two equations. The first one imposes a restriction on the helical field which can be satisfied by a proper choice of satellite helical harmonics. At the same time problem remains to suppress poloidal asymmetry of B² related with toroidicity, the condition described by the second equation.