Development of a methodology for VLEO intake performance testing in a low density facility

Abstract

The objective of this thesis is to design a test procedure within a high vacuum installation with the aim of providing the transmissivity to a fast flux of particles. This parameter is of paramount importance to the evaluation of the intake performance.

First, the pressure evolution within the two chambers of the installation is simulated based on a 0-D model implemented in MATLAB. The model is based on kinetic theory and determines an expression for all the flows circulating in the vacuum facility. It allows defining the various factors impacting the facility operation and the relevant intake perfomance parameters.

Then, a series of tests is proposed. These are required to determine all facility operational parameters which are not measurable directly or within a single test. Two assumptions are considered to determine the intake performance. We will show that one can provide slightly more precise measurements than the other

Finally, an analysis of the error propagation is realized to estimate the uncertainty of the test results. The large uncertainties associated with some of the tests increase the uncertainty associated to the fast flux transmissivity estimative. This uncertainty depends not only on the analytical reasoning chosen but also on the configuration. The developed 0-D model and uncertainty propagation will be used in the future to assist in the configuration definition of the VKI low density facility. Moreover, the 0-D model will be valuable to retrieve the relevant transmissivities from interpretation of each chamber pressure.