热真空试验中分子污染敏感单机的失效机理及对策

卫星大量应用的电缆塑料绝缘层、粘结剂、导热硅脂等非金属材料，在热真空试验过程中逐渐出气并产生分子污染物，可能会造成敏感单机失效的问题。文章对失效机理进行了理论分析，根据总离子流色谱图确定了分子污染物的成分，由此提出利用真空烘烤试验加速星内非金属材料的出气，同时通过真空静置提高星内真空度的方法，以解决微波开关等分子污染敏感单机在热真空试验中可能发生的失效问题。试验结果表明，失效机理分析准确，提出的措施有效。文章提出的防护对策，已在卫星研制过程中得到推广应用。

Failure Mechanism and Countermeasure of Unit Sensitive to Molecular Contamination in Thermal Vacuum Test

Plastic insulation cables, adhesives, thermal grease and other non-metallic materials are utilized in satellite abundantly. These non-metallic materials gradually outgas and cause molecu- lar contamination in the course of satellite thermal vacuum test, which may lead to failure of sensi- tive units. The failure mechanism is analyzed based on the theory of molecular diffusion. The compositions of molecular contamination are determined based on the total ion current chromato- gram. The countermeasures of vacuum hakeout and vacuum tranquilization are proposed to solve the problems of outgassing and molecular contamination of non-metallic materials. The test results indicate that the analysis of failure mechanism is correct and the countermeasures are effective. Such countermeasures have been applied widely in satellite development.