低温低压条件下辉石粉末的热导率实验分析:对月球及火星表面热环境研究的指示

Laboratory thermal conductivity measurement of pyroxene powder under low temperature and atmospheric pressure conditions:Implication for the studies on lunar and Martian surface thermal environment

在真空条件下矿物粉末热导率的实验测量,可为我们研究月球及行星表面的热属性和热演化,解译热红外和微波探测数据,开展月球及行星探测载荷设计提供重要的数据参数。本研究主要采用改造后的Hot Disk TPS 2500S导热仪对辉石粉末的热导率进行测量。同时,分析了真空度、温度对辉石粉末热导率的影响。实验结果表明:1)热导率随着真空度的降低呈下降趋势,大气压力在1000Pa时,辉石粉末热传导机制发生明显改变。在低压条件下(<1000Pa)热导率随真空度的变化趋于平缓;2)辉石粉末热导率随温度的升高而增大,但是增大的幅度在低压和常压条件下存在明显差异。根据实验结果,提出了低压条件下辉石粉末热导率随真空度和温度变化的关系式。本研究表明,在月球和火星表面热环境的研究中,温度和压力对热导率的影响程度是不同的。上述结果对未来开展地外样品的热导率测量提供了重要的参考。

Laboratory studies on thermal conductivities of particulate minerals under vacuum condition can provide essential parameters when determining thermal properties and thermal evolution on lunar and planet surface, interpreting microwave and thermal infrared data and designing lunar explorer. Using modified thermal conductivity measuring instrument （ HOT DISK TPS 2500S）, pyroxenes powder samples are measured for their thermal conductivities under various vacuum degree and temperature conditions. By doing this, we evaluate the effects of vacuum degree and temperature on thermal conductivity of pyroxene powder. The experimental results show, 1 ） thermal conductivity of pyroxene powder decrease with lower vacuum degree. There is an apparent change of heat conduction mechanism when vacuum degree is around 1000Pa. Under low vacuum degree condition, thermal conductivity changes slowly with atmospheric pressure; 2） Thermal conductivity of pyroxene powder increase with temperature, but in different ways between low and normal atmospheric pressure conditions. With the experimental data, quantitative relationships of thermal conductivity of pyroxene powder and vacuum degree/temperature are given under low atmospheric pressure conditions. Our results imply that vacuum degree and temperature play different roles in thermal conductivity studies on lunar and Martian surface. Thus this study provide a reference for thermal conductivity determination of thermal conductivity in future work.