低温接触热导对冷冻靶温度场的影响规律

通过理论推导得出低温条件下不同接触方式的接触热导计算模型,与已有的实验结果对比分析,发现该计算模型具有较高的计算精度,并将该计算模型应用至惯性约束冷冻靶数值模拟计算中,结果表明:硅/铝合金接触热导的值随着装配条件、接触面的接触压力和表面粗糙度等因素改变而发生较大变化,在接触压力为0.2MPa,表面粗糙度为0.1μm工况下,其接触热导值在6.7-56 kW·m^2/K;控制硅冷却臂与TMP结构冷环接触面间的的接触热导大于10kW·m^2/K,能够使靶丸外表面的温度分布均匀性、黑腔系统的换热能力与接触热导无穷大的理想状态偏差小于16%,对于胶Stycast 1266,为满足该条件,所允许的名义胶层厚度约为3μm。在实际工程中,利用接触热导预测公式可以反向推导硅冷却臂卡爪与TMP冷环间所需的压紧力控制范围,尽可能削弱接触热阻的影响。

Investigation on thermal distribution of cryogenic target with low-temperature thermal contact conductance

A theoretical model was developed to calculate the low-temperature thermal contact conductance at different contact conditions. Model validation was then performed and the predicted results show good agreements with the experimental data. Based on this model, the thermal contact conductance in the cryogenic target system was calculated and odopted as an important input parameter in the numerical simulation on the thermal distribution of cryogenic target. The results show that the thermal contact conductance between the silicon arm and the aluminum Thermo-Mechanical Package(TMP) varies greatly with the contact pressure, surface roughness and assembling state. At a contact pressure of 0.2 MPa and a surface roughness of 0.1 μm, the thermal contact conductance ranges from 6.7 kW·m^2/K to 56 kW·m^2/K. When this thermal contact conductance is greater than 10 kW·m^2/K, the deviation of the temperature uniformity from the ideal condition is less than 16%. For bonding agent Stycast 1 266, nominal thickness is determined to be less than 3 μm. In engineering applications, the thermal contact conductance model can be used to determine the critical compression force between the silicon jaws and the TMP so as to minimize the influence of the thermal contact resistance.