Equilibrium and Stability of Flux-Core Spheromak with Finite Pressure

Abstract

The equilibrium and the stability of flux-core spheromak plasma with finite pressure are analyzed and the effects of the flux core are investigated. CTCC-II spheromak is used as the FC (Flux Conserver) model of the flux-core spheromak and the MHD equilibrium configurations are determined numerically. By use of these configurations, it is shown that the magnetic field profile of ordinary spheromak transits into the field profile where the toroidal magnetic field decreases monotonously with the distance from symmetric axis, when λ decreases from λ₀. Here, λ is the ratio of the flux-core current to the flux of the flux core, and λ₀ is the lowest eigenvalue of the Grad-Shafranov equation when plasma is bounded all by a conducting wall. In midway of this transition, the plasma confinement is shown to be worsened. The profiles of the safety factor q and dV⁄dψ also show characteristic variation for the transition. This transition characterizes the flux-core spheromak from other reactors.