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

在低温器件的热设计中，一个非常需要的信息是热物理性质的信息，如比热、导热系数和热扩散系数。因此，开发一种简便的方法来测量这些属性对于构建大型数据库是非常重要的。因此，本文提出了一种矩形脉冲加热的瞬态方法，用于测定结构材料在液氦低温区的热物理性质。测试温度范围分别为4.44-9.15[K]和4.73-15.62[K]的酚醛树脂（酚醛树脂）和聚四氟乙烯（聚四氟乙烯）。对数值方法进行了进一步的研究，并对本文的解析方法进行了验证。在测试温度范围内，它们的比热和导热系数随温度的升高而增大，而热扩散系数随温度的升高而减小。结果还表明，电木清漆和聚四氟乙烯的比热以及聚四氟乙烯的导热系数与我们的研究结果相似。从而验证了暂态方法的有效性。还发现，用数值方法可以预测固体的温度偏移。

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.