INVESTIGATION OF NEAR CRITICAL POINT STATES OF LITHIUM, SODIUM AND ALUMINIUM BY PULSE HEATING DURING LAUNCHING

Abstract

The results of experimental investigation of near—critical point states of liquid‐vapour phase transition of of lithium, sodium and aluminium are presented. The metal foil samples were launched by explosively driven steel plate in Helium atmosphere; Li and Na—by direct impact and Al—by impact through the layer of helium. The heating of the Li and Na foils were performed by heat exchange with shocked He layer from the free side of sample; Al—by heating by multiple‐shocked He from the back side of the foil. The temperature of sample surface was measured by fast multi‐channel optical pyrometer. For Li and Na experiments the pressure was obtained from measured shock velocity in helium using base length technique; the 1‐D simulation of the process of launching was performed to obtain pressure for Al experiments. The obtained experimental information allowed to evaluate liquid spinodal line, and the position of critical points on pressure—temperature plane for investigated metals.