FINITE-β MAGNETIC FIELD LINE TRACING FOR HELIAS CONFIGURATIONS

摘要

A new code, Magnetic field solver for Finite-Beta Equilibria (MFBE), has been developed. It computes the magnetic field in a form suitable for field line tracing inside and outside the plasma boundary of finite-β Helias equilibria calculated with the NEMEC free boundary equilibrium code. Coupling of the NEMEC and MFBE codes allows a determination of-the last closed magnetic surface. For various β values up to <β> ≈ 0.04, the variations of the island sizes and positions outside the plasma boundary and the ergodization of the edge region are studied for a Helical Advanced Stellarator (Helias) configuration (Nuhrenberg and Zille, Phys. Lett. A 114 (1986) 129).