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Persistent URL http://purl.org/net/epubs/work/54024746
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Record Id 54024746
Title Investigation of the Effect of Temperature on the Molecular Contamination of Thermal Vacuum Chambers
Abstract In this study, the effect of the contamination source temperature and the use of a cold trap at two different temperatures on the deposited molecular contamination on a thermal vacuum chamber are investigated. A 1.2m (diameter) x 1.2m (length) chamber was selected for such an investigation. Six different test scenarios were executed to show the effect of contamination source temperature on the observed contamination at various locations in the chamber. Four different known contamination sources - Poly(methylphenylsiloxane) (PMS), Polydimethylsiloxane (PDS), Paraffin liquid and Dioctyl phthalate were used in order to assess a range of contaminants. To quantify the deposited contamination in the chamber, molecular contamination (MOC) windows were placed at different locations within the chamber and were then analysed using FTIR (Fourier-transform infrared spectroscopy) (Bruker, Alpha II FTIR G1004517) from which the results are obtained in terms of mass per area (ng/cm2) with the equivalent of Aliphatic Hydrocarbon, Aromatic Ester, PDS and PMS. The results of this study show that at standard bake-out temperatures of up to 80°C, silicone contamination in the form of PMS and PDS is far less than expected with PDS contamination not observed at any temperature and PMS only detected during the 80°C cases. The ester and hydrocarbon sources were found to be more capable of contaminating items in the chamber with up to 100% of the source material being vaporised during the 80°C tests and high molecular contamination readings observed on the 20°C reference plate. However, it was found that the risk of molecular contamination to items in the test chamber could be greatly reduced when a cold trap is used in the test, with contamination readings reduced from 3600 ng/cm2 observed on the reference plate when no cold trap was used, to 478 ng/cm2 and 51 ng/cm2 for the -70°C and -180°C cold traps respectively.
Organisation STFC , RALSP , RAL Space - ETD
Keywords TVAC , outgassing , cold-trap , silicon contamination , vacuum chamber , contamination
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Language English (EN)
Type Details URI(s) Local file(s) Year
Conference Proceedings 31st Space Simulation Conference 2022, Annapolis, Maryland, 17-20 Oct 2022. Institute of Environmental Sciences and Technology (IEST), 2022 https://www.proceedings.com/66155.html 2022