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Published: 2015

Total Pages: 17

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Explosively-driven magnetic flux compression generators create substantial currents (10's of mega-amps) by compressing magnetic fields initially created by injected seed currents. In a Ranchero generator it is the field between two cylinders of aluminum that is compressed when the inner cylinder (armature) is driven across the magnetized gap toward the second cylinder (stator) [1]. All Rancheros to date have used the explosive PBXN-110, but future devices are expected to use PBX-9501 because of several advantages of the latter over the former. For Ranchero applications, though, a potentially important disadvantage stems from the requirement that the large PBX-9501 charges (15 to 50 kg) must built up from smaller machined pieces rather than cast into the appropriate shape as with PBXN-110. Calculations [2] and related experiments [3] raise the possibility that jetting may occur at gaps between machined pieces of PBX-9501 and lead to localized failure of the soft aluminum armature causing premature contact of the armature with the stator or, in the most extreme case, a severing of the armature into separate pieces and a subsequent loss of current. A set of small-scale experiments has been designed to provide Ranchero designers and users insight into the effects of gaps and also to provide useful data for the validation of Ranchero calculations. These experiments should be executed in early May 2015. The code Rage [4] was used to model the small-scale experiment and this paper presents the results. The emphasis here is on the calculations and the experimental details are limited, so the interested reader is referred to reference 5 for a fuller description of the experimental configuration and diagnostics. Less-interested readers may be interested in only a summary of results and are directed to the "Summary of key results" section later in this paper.