Transient measurement apparatus for material thermal conductivity at ultra-low temperature

Abstract This study was an important attempt to apply the transient plane heat source method to the thermal conductivity measurement at ultra-low temperature. First of all, a detachable cryogenic thermostat was designed, which used a GM cryocooler to obtain the cooling capacity, and transmitted the cooling capacity of the secondary cold head to the test chamber through the copper cold chain. The chamber was filled with cryogenic helium gas, where the sample was mounted. The precooling process, heat leakage and temperature field division were simulated by finite volume method, and the results verified the rationality of the structural design. Secondly, the measurement probe of the transient plane heat source method was recalibrated at low temperature. Finally, the thermal conductivities of 304 stainless steel and polyurethane at low temperature were measured, and the values were compared with those in the literature, so as to verify the reliability of the measuring device.