Escaping and transport barrier due to ergodic magnetic limiters in tokamaks with reversed magnetic shear

摘要

Analytical tokamak plasma equilibria, with non-monotonic plasma current profile and perturbed by ergodic magnetic limiters, are described by non-twist conservative maps. Examples are given of concentration of magnetic field lines escaping to the tokamak wall. The robustness of invariant curves on the shearless region is also observed.