Cryocooler Load Increase due to External Contamination of Low-∈ Cryogenic Surfaces
Cryocooler Load Increase due to External Contamination of Low-∈ Cryogenic Surfaces
复制标题
由于低ε低温表面的外部污染导致低温冷却器负荷增加
DOI：
10.1007/0-306-47919-2_95
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
R. Ross
中科院分区：
文献类型：
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作者：
R. Ross
空间仪器低温系统设计者面临的一个重要挑战是，在使命的整个寿命期间，为可能受到冷凝水膜或其他除气产物影响的低发射率低温表面实现稳定的发射率值。通常，低发射率低温表面吸收厚度随时间增加的水膜，并且可能导致低温热负荷的显著增加。如果达到过大的负载水平，低温表面必须“crossted”通过提高它们到高温蒸发的污染物film.As帮助那些设计和进行未来的长寿命任务与低温制冷机，本文总结了适用的物理与表面污染和汇编的例子飞行数据在多年的空间任务和地面测试中所经历的污染影响。飞行和地面试验数据，然后进行了比较与污染传输率和污染膜厚度的依赖发射度的物理参数。虽然测试样本很小，但数据表明，由于低∈表面的污染，预计在轨载荷可能增加10-20%左右。这个水平被认为是一致的膜厚度和预期的污染物水平在空间中的发射率的灵敏度。
An important challenge for the cryogenic system designer of space-instruments is achieving stable emittance values for low-emittance cryogenic surfaces that may be affected by condensed water films or other outgassing products over the life of a mission. Typically, low-emittance cryogenic surfaces getter water films that increase in thickness over time and may lead to significant increases in the cryogenic heat load. If excessive load levels are reached, the cryogenic surfaces must be “defrosted” by raising them to elevated temperatures to evaporate the built-up contaminant films.As a help to those designing and conducting future long-life missions with cryocoolers, this paper summarizes the applicable physics associated with surface contamination and compiles example flight data on contamination effects experienced during multi-year space missions and ground tests. The flight and ground test data are then compared with the physical parameters involved with contamination transport rates and the dependence of emittance on contaminant film thickness. Although the test sample is small, the data indicate that around a 10–20% load increase may be expected on-orbit due to contamination of low-∈ surfaces. This level is found to be consistent with the sensitivity of emittance to film thickness and the expected contaminant levels in space.