Observations on one-dimensional counterflow diffusion problem

Michael S. Woronowicz

doi:10.1117/12.481646

11 September 2002 Observations on one-dimensional counterflow diffusion problem

Michael S. Woronowicz

Proceedings Volume 4774, Optical System Contamination: Effects, Measurements, and Control VII; (2002) https://doi.org/10.1117/12.481646
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

The proposed paper will describe development of a time-dependent, one-dimensional counterflow diffusion model meant to help study the issue of helium exposure of the IRU (Inertial Reference Unit) used in the Earth Observing-1 (EO-1) spacecraft. The IRU features sensitive quartz crystal hemispherical resonating gyros (HRG's). Although the IRU enclosure was purged with high-purity liquid boil-off nitrogen, the HRG's were still quite susceptible to contamination generated by exposure of the enclosure to levels of helium above atmospheric background levels. This helium would be preferentially collected by the HRG's, changing their mass, and hence the driving voltage required for operations. The paper will discuss a comparison of theoretical results with test data for an IRU enclosure, and how contaminant gases can enter vent holes despite the presence of a purge. These observations are then used to describe a possible improvement for purge effectiveness.

Citation Download Citation

Michael S. Woronowicz "Observations on one-dimensional counterflow diffusion problem", Proc. SPIE 4774, Optical System Contamination: Effects, Measurements, and Control VII, (11 September 2002); https://doi.org/10.1117/12.481646

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