Ohmic heating in a double-taper sabot-armature

Abstract

A two-dimensional model, developed previously to investigate the transport of electromagnetic fields and energy in solid-armature railguns, is simplified to study exclusively heating within the interior of the armature. The simplifying assumptions, made in order to reduce the time required for calculations, include neglecting the effects of velocity as well as the details of the physics occurring at the rail-armature interface. These assumptions are not believed to be particularly restrictive when the intent of the calculations is to investigate regions of the armature that are far removed from the rails. The governing equations, appropriate under this set of assumptions, are presented. The model is then applied to analyze current and heat transport in a double-taper sabot armature, a type of armature that is currently under active study and is known to be valuable in launching high-density tactical payloads. In particular, calculations are undertaken to investigate the manner in which a variation of certain geometrical parameters that define the shape of the armature affect the time evolution and spatial distribution of temperature, fields, and forces within the armature. Results of the calculations are studied carefully and explained by basic physical principles.