MHD simulation of moving arcs

Arcs moving due to Lorentz forces in gases in the range from normal to high pressure are used in several technical applications. A time-dependent 3D simulation solving the MHD (Magneto-hydrodynamic) equation system is applied here to study the behavior of a moving high-pressure arc in more detail. As examples, arcs in dry air and in SF6 gas rotating in a cylindrical arrangement between ring-shaped electrodes due to an external radial magnetic field are analyzed. Local Thermodynamic Equilibrium (LTE) is assumed. Recalculated data for gas composition are applied. The thermodynamic properties have been determined by self-consistent kinetic models. The arc model has been implemented into a commercial fluid dynamics package which solves the Navier-Stokes equations and Maxwell’s equations. Results allow the determination of the arc velocity and a comparison with analytical estimations. The impact of the lateral blowing is studied by a numerical experiment comparing the arc behaviour with and without the radial magnetic field.