Molecular incidence rate in a cylindrical space simulation chamber with spherical test object

Abstract

In connexion with a research programme a need emerged for a theoretical investigation of the molecular fluxes inside a cylindrical space simulation chamber with a spherical test object as gas source. The first of a series of problems to be dealt with will be the distribution of the molecular incidence rate, I, and molecular emission, E, over the surface of the cold wall (shroud) and the test object. The previously developed theory of molecular fluxes in nonisothermal containers14,15 will serve as a basis. The basic equations for treating the problem in question are set up and a solution procedure for the integral equations, with the probability matrix for the molecular exchange at finite part surfaces, is given. The coefficients of the probability matrix are calculated for all surface element combinations, which may occur in the space simulation chamber with a spherical test object. These coefficients are calculated for infinitesimal as well as surfaces of finite size. In two limiting cases general solutions of the integral equations for the molecular incidence rate, I, and the emission, E, may be used; capture probability of the cryogenic surface, s = 1 and s ≪ 1. For intermediate values of s, solutions especially for the DFVLR space simulation chamber are derived with help from the computer. Practical applications will be referred to. © 1971.