First tests of an extremely high mass sensitivity: miniature TQCM, which is impervious to solar thermal radiation effects

Donald A. Wallace; Scott A. Wallace; Kenneth W. Rogers

doi:10.1117/12.328522

27 October 1998 First tests of an extremely high mass sensitivity: miniature TQCM, which is impervious to solar thermal radiation effects

Donald A. Wallace, Scott A. Wallace, Kenneth W. Rogers

Author Affiliations +

Proceedings Volume 3427, Optical Systems Contamination and Degradation; (1998) https://doi.org/10.1117/12.328522
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1998, San Diego, CA, United States

Abstract

Quartz Crystal Microbalance (QCM) sensors have long been used in space to measure outgassing molecules being emitted by spacecraft materials or, alternately, erosion effects made by striking the spacecraft with some external molecular flux, e.g., atomic oxygen. However, the measurements produced by the QCM have been hard to meaningfully interpret because of solar thermal radiation effects. Normally, in a QCM, a sense crystal is exposed to space to measure the appropriate mass flux, but the reference crystal is hidden from this exposure. Crystals used in QCMs not only have a mass sensitivity but also have a temperature sensitive component. When the vagaries of spacecraft motion and thus QCM motion is considered, the sense crystal sees the sun at various times and at various angles. When exposed to sunlight, the QCM changes frequency because thermal radiation strikes and exposed crystal and not the reference crystal. We will report on the findings of a new Thermoelectric QCM with two exposed crystal, and the effects of sunlight on it. With both the sensor and the reference crystal exposed to thermal radiation and thus eliminating the offset frequency, the resulting beat frequency will reflect only the mass flux and the data will be easier to interpret.

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Donald A. Wallace, Scott A. Wallace, and Kenneth W. Rogers "First tests of an extremely high mass sensitivity: miniature TQCM, which is impervious to solar thermal radiation effects", Proc. SPIE 3427, Optical Systems Contamination and Degradation, (27 October 1998); https://doi.org/10.1117/12.328522

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