Fluid simulation of a low-pressure axisymmetric toroidal plasma using natural coordinates

A numerical model is developed to study the confinement of low-pressure plasmas in axially symmetric configurations with arbitrary shaped magnetic surfaces. The equations contain the effects of resistivity, plasma inertia, and pressure gradients in the surfaces. In this model, which extends the earlier work in which fictitious currents had to be introduced to support the magnetic fields, the plasma pressure is taken sufficiently small that only electrostatic modes can be excited. The Lax-Wendroff scheme is used to advance the plasma density and velocities in time. Applications include demonstration that classical expressions for diffusion are valid when there are small plasma flows, and study of the propagation of acoustic and geodesic waves in levitrons.