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

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