Abstract
The reduction of thermal outgassing from stainless steel by surface polishing or vacuum firing is well-known in vacuum technology, and the consequent use of both techniques allows an even further reduction of outgassing. The aim of this study was to identify the effectiveness of surface polishing and vacuum firing for reducing electron-stimulated desorption (ESD) from 316LN stainless steel, which is a frequently used material for particle accelerator vacuum chambers and components. It was found that, unlike for thermal outgassing, surface polishing does not reduce the ESD yield and may even increase it, while vacuum firing of nonpolished sample reduces only the H2 ESD yield by a factor 2.
Highlights
The process of thermal desorption has been intensively studied in the past because it is a significant source of gas in many ultrahigh vacuum and extreme high vacuum systems
051601-2 Malyshev, Hogan, and Pendleton: Effect of surface polishing and vacuum firing on electron-stimulated desorption (ESD) from 316LN
051601-3 Malyshev, Hogan, and Pendleton: Effect of surface polishing and vacuum firing on ESD from 316LN
Summary
The process of thermal desorption (thermal outgassing) has been intensively studied in the past because it is a significant source of gas in many ultrahigh vacuum and extreme high vacuum systems. Most interest has been concentrated on the materials used to manufacture vacuum chambers and components, such as stainless steel, copper, and aluminum. In the design of a large vacuum system, stainless steel is the most common material selected for the vacuum chambers because it can routinely achieve a value of gt 1⁄4 10À12 mbarÁl/(sÁcm2) for hydrogen (and much lower for other species) after a 24-h bakeout at 300 C.1. Further reduction can be achieved using the methods of an air bake, vacuum firing, and surface polishing. The best outgassing results of gt 1⁄4 10À15 mbarÁl/(sÁcm2) have been obtained after performing either an air bake or a very fine polish and subsequent vacuum firing at a pressure better than 10À6 mbar.
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