Response of Thermocouple Junctions to Shock Waves.

摘要

Experiments were conducted to determine the wave form and amplitude of the voltages produced when a shock wave passes a thermoelectric junction. Shock waves were produced in flat plates over pressure ranges of 50 to 400 kilobar by the impact of flat-faced projectiles on the plate. Junctions were made by mounting a second material on the surface of the plate on the side opposite the impacted side. Experimental details and results are given. Copper and iron plates were used with the following materials as the second material of the junction: copper, constantan, cobalt, bismuth, silicon (pure, n-type, and p-type) and germanium (pure, n-type, and p-type). Results show that output voltages are generally higher than would be predicted from known, static, thermoelectirc powers and shock-wave heating. Flow of material is shown to have a significant effect on the output. This indicates that alternation of material structure and properties, either by the dynamic compression process or by flow, is significant in determining the output observed. Bismuth-copper junctions show a phase change. The rise times of voltage wave forms are indicative of the time required for equilibrium to be attained behind a shock wave. Various pressure transducers were designed based on these junctions. (Author)