A compound opening switch for electromagnetic launch applications

The authors describe a repetitive compound opening switch capable of carrying mega-ampere currents and holding tens of kilovolts while opening in the submillisecond regime. The switch is made up of three elements. First, a wide foil to carry large currents for long periods of time is ripped open at sonic velocities to transfer the current to a fuse. The fuse then provides commutation and voltage holding, also allowing time for the foil opening to clear. The third element is a CVR (constant voltage resistor) with an I-V characteristic like that of back-to-back Zener diodes. The CVR limits the voltage excursion of the fuse. The current is transferred to the CVR from the fuse before it explodes, and the required switch dissipation is provided in the CVR. Analysis of this compound switch, including fundamental limitations and design issues, is presented. Preliminary experimental results for foil ripping and the fuse/CVR combination are included