Surface Heating of Molybdenum, Tantalum, and Tungsten Rods by Pulsed Currents

Abstract

Abstract : Measurements of the surface voltage and surface temperature are made for small molybdenum, tantalum, and tungsten rods that have been subjected to pulsed electrical heating. The heating time is from 100 to 200 microseconds. The experimental results are then compared to results obtained from calculations undertaken with a numerical model that accounts for diffusion of current and ohmic heating within the sample. Good agreement between theory and experiment is obtained for the voltages and the temperatures. This agreement (a) provides valuable confirmation of the theoretical models and the experimental techniques used in Army applications of pulsed power; (b) demonstrates that the thermophysical properties of these substances are not affected by the rapid heating rates necessary in those applications; and (c) suggests a coupled experimental and theoretical technique for measuring resistivity in substances for which that property is not well known. The methodology for measuring the resistivity is developed and demonstrated in a sample experiment and calculation.