Experiments with Explosively Formed Fuse Opening Switches in Higher Efficiency Circuits

We have previously reported on the development of explosively formed fuse (EFF) opening switches for use in applications where very long conduction times (lO's or lOG's p.s) are required and where opening times of 1-10 p.s are adequate. In this paper we report on the development of an EFF that allows magnetic flux in the switch to be delivered to the load rather than lost from the circuit. The topology of this device is substantially different from earlier versions and contains new design constraints. In the most strenuous test to date, we delivered 7.5 MA to the EFF from a small helical explosive driven magnetic flux compression generator, and completely turned off the current in the remaining 34-nH circuit in ~3 p.s producing a 140-kV pulse. The switch in this test is 15 em in length. We also report on work with EFFs in this configuration tailored for slightly longer opening times.