tion of Liquid-Metal Jets as the Conductor in a ated, Exploding-Fuse Opening Switc
A repetitive, high-power opening switch technique for use in pulsed power applications using inductive energy storage is presented, along with data which demonstrate performance characteristics. This technique uses jets of a liquid conductor to replace the solid metal fuses in exploding-fuse opening-switch designs. High-power switching characteristics such as interrupt current, holdoff voltage, and resistance change are presented, along with information on how these characteristics change as jet length and circuit parameters are varied. A simulated load is used to demonstrate that exploding liquid-metal jets are feasible replacements for solid-fuse conductors in realistic applications. Likewise, the switching facility has been rep-rated in a two-pulse scenario to show its primary advantage over solid-fuse switches. The use of a highspeed camera to monitor the expansion of the mercury column upon vaporization is also described. Radial expansion velocities have been extracted from the images and are correlated with the electrical data.
The Voltage across a Fuse during the Current Interruption Process
Results of experiments with fusing wires are discussed and explained theoretically. Multiple arcing is observed; it is explained in a thermodynamic model. Also, the possible absence of multiple arcing at high currents is explained. There, evaporation of superheated fuse material causes the fast increase of the fuse resistance. This evaporation explains the experimentally observed behavior of the fuse resistance as a function of fuse diameter, whereas the concept of multiple arcing fails to do so. Results from experiments confirm energy balance equations, both for fuses in air and for fuses embedded in fine-grained sand. The energy balance equation for the latter case is shown to be equivalent to Mayr's equation.
New observations on the formation of unduloids on wires
The paper presents the results of an investigation of unduloid formation on hard-drawn and soft silver wires with diameters between 0.16 and 1.0mm. It has been established that unduloids only form on hard-drawn wires. Consequently, unless wire surface hardness is taken into account, the existing theories about the surface melting of current-overloaded wires may be incorrect. Furthermore, experiments are reported on hard-drawn and soft wires heated with a gas flame where a similar formation of unduloids only occurred on the hard-drawn wires. It has been found that, for both soft and hard-drawn wires, there is a close similarity between their behaviour when heated by either a gas flame or an electric current.