Structural eddy current effects on plasma equilibrium and current induction in the IGNTEX experiment

Abstract

In the IGNITEX device the plasma is surrounded by massive conducting material composed of several layers. From inside to outside the layers may be categorized as: first wall-vacuum vessel, poloidal field magnet system, inner toroidal field magnet region with slits and outer homogeneous toroidal field magnet region divided into twelve sectors. The 2-D finite element program PROTEUS is employed to study current induction and plasma equilibrium throughout the ignition discharge. Some modifications of the original code PROTEUS which permit the study of compact plasmas with strong wall coupling are described.The structure layers are simulated either as diffusive or as a set of electric circuits properly connected. Different resistivity models are considered. The calculations presented here show that the flux swing produced by the poloidal field (PF) coil system is enough to induce over 12 MA of plasma current and that a sequence of equilibrium configurations with elliptical cross sections can be obtained by properly choosing the waveforms of the PF system currents throughout the discharge of 10 seconds. The effects of the eddy currents on the discharge are dependent on the resistivities of the material and are substantial if the resistivities are low. Thus, the importance of a consistent equilibrium calculation coupling plasma, coils and structures is demonsirated.

MHD Equilibrium Configuration Reconstructions for HL-2A Tokamak

“…The information about the magnetohydrodanymic (MHD) equilibrium configuration is essential in tokamak experiment for either the control of the configurations [1,2] or the detailed information, e.g., the profiles of plasma parameters such as safety factor q, pressure p and current density j. Quite a few numerical codes have been successfully developed and used in the past few decades [3∼5] .…”