Vacuum in space—an isotropic regime?
1990; Elsevier BV; Volume: 41; Issue: 7-9 Linguagem: Inglês
10.1016/0042-207x(90)94171-l
ISSN1879-2715
Autores Tópico(s)Astrophysics and Star Formation Studies
ResumoIn ground based vacuum, we are used to thinking in terms of an isotropic distribution of molecules concerning density and velocity. This is justified as long as the apparatus has an entirely homogeneous temperature distribution. These conditions change as soon as higher or lower temperatures for parts of the facility, or in the process executed in it, are involved. In earlier works of the authors, theoretical and experimental results have been shown about molecular flow distributions in a space vacuum chamber, with a LN2 cooled shroud and a gas source at room temperature. In 1970 R N Kostoff proposed a Molecular Wake Shield for use in space that had been in a dormant state for several years. In near Earth space, the thermal velocity of molecules is much smaller than the orbit velocity of a spacecraft. On the wake side of an orbiting shield, an area exists with no residual gas atmosphere particles in it. The wake side desorption of the shield is the existing gas source, with a directional flow of molecules. With this an anisotropic area is built up that can be used for research and industrial application of e.g. surface treatment, materials purification and film coating under ultra pure conditions. The basics of this regime and its first experimental realization will be described in the paper.
Referência(s)