Practical expressions for local magnetic shear, normal and geodesic curvatures in an axisymmetric plasma equilibrium of arbitrary cross-section

摘要

We present practical expressions involving the toroidal field and the poloidal flux that describe without approximation the local magnetic shear and normal and geodesic curvatures in an axisymmetric plasma equilibrium of arbitrary cross-sectional geometry. Experimental examples from the ASDEX Upgrade tokamak indicate that a zero crossing of both local shear and poloidal current density in the outboard pedestal region first occurs with the appearance of edge localised modes.