| AVS 61st International Symposium & Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT-TuA |
| Session: | Vacuum Quality Analysis, Outgassing, and Control |
| Presenter: | Freek Molkenboer, TNO Technical Sciences, Netherlands |
| Authors: | F.T. Molkenboer, TNO Technical Sciences, Netherlands A. Van de Runstraat, TNO Technical Sciences, Netherlands J.A. Van der Meer, TNO Technical Sciences, Netherlands T. Van Groningen, TNO Technical Sciences, Netherlands O. Kievit, TNO Technical Sciences, Netherlands |
| Correspondent: | Click to Email |
Residual gas analyzers (RGAs) are commonly used in ultra-high vacuum applications to measure vacuum quality. The RGA fragments and ionizes the molecules that are present in the gas phase in the vacuum system. These fragments of all the molecules make up the RGA spectrum. The RGA spectrum has to be interpreted to identify the contaminants that are present in the vacuum system. This is complicated and often impossible in case of complex mixtures of organics in the vacuum atmosphere.
The goal of this project is to develop a simple-to-use diagnostic tool that is able to identify the contaminant molecules in vacuum directly. After a trade-off of various options, we selected a removable cold trap in combination with an off-line gas chromatography–mass spectrometry ( GC-MS) system for analysis of the samples.
The cold trap is installed on a vacuum flange. A removable sample tube is positioned inside the cold trap in connection with the vacuum system. The cooling of the cold trap is achieved with Peltier elements, which makes it simple to operate as well as independent of supply of coolants such as liquid nitrogen. After sampling, the sample tube can be removed without venting the vacuum system and a new sample tube can be installed to continue measurements if required.
After sampling of the vacuum vessel, the sample tube is connected to a GC-MS system for analysis of the sample and identifying and partly quantify the organic molecules present.
The first results are promising and we continue to improve the system. In this presentation we will present our sampling method and the results of vacuum quality measurements using the new diagnostic tool.