MEASUREMENT OF THERMOPHYSICAL PROPERTIES OF SOLID BODIES AT LOW TEMPERATURE REGION OF LIQUID HELIUM

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One of the information that has been in great demand in thermal design of the cryogenic devices is that of the thermophysical properties such as the specific heat, the thermal conductivity and the thermal diffusivity. Therefore, it is of definite importance to develop a handy method for measuring such properties to construct a large body of database. Thus, a transient method with rectangular-shaped pulse heating has been developed to determine the thermophysical properties of substances used often as structural materials at low temperature region of liquid helium. Those tested were Bakelite (Phenolformaldehyde resin) and Teflon (Polytetra-fluoroetliylene) in the temperature ranges of 4.44-9.15[K] and 4.73-15.62[K], respectively. The further studies for numerical method were made and the present analytical method was verified.It was recognized in the temperature range tested that the specific heat and the thermal conductivity of them increased with temperature, while the thermal diffusivity decreased with that. Results indicated also that the specific heat of Bakelite varnish and Teflon as well as the thermal conductivity of Teflon reported behaved similarly to our present results. Thus the validity of the present transient method was confirmed. It was found as well that the temperature excursion of solid bodies could be predicted by the numerical method.