Magnetohydrodynamics Modeling of Electrothermal Instability Development on Electrically Pulsed Conductors*

The evolution of a conductor driven by multi-megaampere current pulses from solid metal to thermal plasma is of great interest when designing imploding liner inertial confinement fusion experiments, magnetically driven flyer plates for material science tests, and electrical initiators for high explosives. The electrothermal instability (ETI) propagates unstable temperature perturbations in the conductor that deform the metal and limit its ability to carry current. They can develop from axial machining perturbations and resistive inclusions/voids in the metal—both of which divert the current and lead to preferential Joule heating. The resistive MHD code FLAG is used to model electrically thick rods driven by the ~1 MA, ~100 ns Mykonos current driver as well as thin wires and hollow liners with equivalent current densities to interpret experimental results showing ETI growth.