MHD Evolution of an Electric Arc in Fuses

A basic dynamic and thermodynamic description of the behavior of a metal fuse in an inert gas, such as nitrogen, at atmospheric pressure is provided. A first-principles MHD description was used for the evolution of the melting fuse and the surrounding gas. Fundamental issues include the possible explosive evolution of gaseous discharge within a closed enclosure and the possible onset of pinch instability, which cuts the molten fuse current channel. Herein, I discuss some basic 2-D description focusing on the dominant nonlinear mechanisms of fluid processes during the plasma prearcing stage. It is found that breaking of the melting fuse current channel, by pinch effect, is favored by a viscous ambient fluid and notches in the fuse lead to concentration of pressure and magnetic energy.