PUMP-DOWN CHARACTERISTICS OF OUTGASSED CLEAN STAINLESS STEEL VACUUM CHAMBER AND SURFACE ANALYSIS OF THE CHAMBER WALL

摘要

In order to investigate pump-down characteristics of extremely high vacuum, a vacuum chamber made by clean 316L stainless steel treated by both electropolishing and outgassing at 800 degrees C was prepared. This chamber was evacuated by a cryosorption pump. The evacuation time to achieve the extremely high vacuum was shorter than that of an Al alloy chamber with the same size and vacuum system, when the evacuation scenario and the baking condition were kept the same. For the material used for the vacuum chamber, the surface atomic composition and chemical bonding state were analyzed by AES and XPS, respectively The mixture of compositions of Fe2O3, FeO and Cr2O3 was observed on the surface. The gas desorption was also measured by a technique of TDS. The amount of hydrogen desorbed during heating up to 1000 degrees C from the present clean material was one order of magnitude smaller than that of untreated 316LSS. Copyright (C) 1996 Elsevier Science Ltd. [References: 16]