MACH2 simulation of an explosively formed fuse opening switch

Summary form only given, as follows. MACH2 is a general purpose MHD code that previously has been used to simulate a wide variety of pulsed power plasma devices. Recent extensions to the code permit accurate tracking of moving material interfaces. The code has been used to simulate the evolution of an explosively formed fuse consisting of a thin cylindrical aluminum shell that is driven into a Teflon(R) die by an explosion. The resulting rapid increase of the fuse resistance operates as an opening switch to transfer stored magnetic field energy into a load. The simulation included the initiation and propagation of the explosive detonation wave and tracked the extrusion of the fuse into the Teflon die. The transient fuse resistance was determined from the changing inductance and the ohmic heating of the fuse. The code predicted that the fuse resistance increased by approximately three orders of magnitude during a time of approximately 1 microsecond. The increase in resistance was due to the lengthening and thinning of the fuse material and the rise of temperature caused by the ohmic heating. The simulation results will be compared with recent experimental measurements performed at Los Alamos National Laboratory.