Conference Paper

Experimental and Theoretical Analyses of Explosively-Formed Fuse (EFF) Opening Switches

Los Alamos Nat. Lab., Los Alamos, NM
DOI: 10.1109/MEGAGUSS.2006.4530692 Conference: Megagauss magnetic field generation and related topics, 2006 ieee international conference on
Source: IEEE Xplore

ABSTRACT The EFF is used at Los Alamos as the primary opening switch for high current applications. It has interrupted currents from ~10 kA to 25 MA, thus diverting the current into low inductance loads. To understand and optimize the performance of full-scale experiments, many parameters were studied in a series of small-scale experiments, including: electrical conduction through the explosive products; current density; explosive initiation; insulator type; conductor thickness; conductor metal; metal temper; and on. The results show a marked inverse correlation of peak EFF resistance with current density. In this paper we postulate and refute a simple extrusion mechanism of EFF operation; demonstrate that the EFF switch has a near-ideal profile for producing flat-topped voltage profiles; and explore possible mechanisms for the degradation of small scale switch performance.

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    ABSTRACT: A series of 1-D isentropic-compression experiments (ICE) has been initiated using the high-explosive pulsed-power (HEPP) system. Accurate high-stress isentropic equation-of-state (EOS) data had been reported using the HEPP-ICE system. A number of important advantages of the system were demonstrated, including higher stresses, higher accuracy, and larger sample sizes than those of other methods. Several potential design improvements have since been identified and tested. The storage inductor was eliminated, and the experiment was performed before the output of the plate flux compression generator could short-circuit itself. This eliminated the loss of current that occurs when the generator plates bounce apart. A new design of explosively formed fuse opening switch was employed with a multipoint initiation system that reduced the explosive mass, significantly reduced the timing jitter by eliminating air gaps, and minimized flux losses. In addition, with this new switch, the resistance-versus-time profile may be adjusted by controlling the initiation times of its four quadrants. Anomalous results were obtained with the new switch. The results of using this switch in an EOS experiment on pure tantalum are reported.
    IEEE Transactions on Plasma Science 09/2010; · 0.87 Impact Factor

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