Caesium- and sodium-filled pressure controlled heat pipe at NRC

Abstract

Abstract What if you could tune the temperature of the fixed point used to calibrate your thermometer continuously between the freezing points of zinc (692.677 K) and silver (1234.93 K) while maintaining the uniform temperature environment (±10 mK) along 20 cm zone for hours at a time and with an uncertainty approaching a fraction of a mK? We are aiming to do exactly that by using a set of caesium- and sodium-filled pressure controlled heat pipes previously established at NRC. The original pressure controlled heat pipe furnaces have been recommissioned with a number of changes to improve their function as a calibration by comparison apparatus. In particular, the new gas handling system capable of controlling the pressure within ±4 ppm was installed side by side with the previously reported one. In this paper, we show the temperature performance of legacy NRC caesium- and sodium-filled pressure controlled heat pipes when connected to the new gas handling system.