Two-Fluid Flowing Equilibria of Helicity Injected Spherical Torus with Non-Uniform Density

Abstract

Two-dimensional two-fluid flowing equilibria of helicity-injected spherical torus with non-uniform density and both toroidal and poloidal flows for each species have been numerically determined by the nearby-fluids procedure. It is found from the numerical results that the equilibrium for the driven λ (≡ μ0 j·B/B2 ) profile exhibits a diamagnetic toroidal field, high-β (toroidal beta value, βt = 32%), hollow current profile, and centrally broad density. In contrast, the decaying equilibrium exhibits a paramagnetic toroidal field, low-β (βt = 10%), centrally peaked current profile, and density with a steep gradient in the outer edge region. In the driven case, the toroidal ion and electron flows are in the same direction, and two-fluid effects are less important since the E × B drift is dominant. In the decaying case, the toroidal ion and electron flows are opposite in the outer edge region, and two-fluid effects are significant locally in the edge due to the ion diamagnetic drift.