Space simulation ultimate pressure lowered two decades by removal of diffusion pump oil contaminants during operation

摘要

The complex problem why large space simulation chambers do not realize the true ultimate vacuum was investigated. Some contaminating factors affecting diffusion pump performance have been identified and some advances in vacuum/distillation/fractionation technology have been achieved which resulted in a two decade or more lower ultimate pressure. Data are presented to show the overall or individual contaminating effect of commonly used phthalate ester plasticizers of 390 to 530 molecular weight (M.W.) on diffusion pump performance. Methods for removing contamination from diffusion pump silicon oil during operation and reclaiming contaminated oil by high vacuum molecular distillation are described.