A high sensitivity real-time NVR monitorThe use of a temperature-controlled 200-MHz SAW resonator piezoelectric mass microbalance to monitor the mass of nonvolatile residue (NVR) deposited on its surface in real time is reported. The fundamental frequency of this device is mainly dependent on the configuration of the transducers and not on the thickness of the substrate. Therefore, higher operating frequencies can be achieved without reducing the thickness of the crystal. The real-time instrument was integrated onto a conventional stainless steel NVR plate and operated flawlessly over a 14-d period at Kennedy Space Center and successfully measured less than 1 ng/sq cm d NVR contamination. Contamination episodes detected by the instrument were correlated with scheduled activities on the test stand. Under the assumption of a baseline noise level of +/- 2 Hz, the absolute mass lower limit of detection would be 0.065 ng/sq cm. This would enable the detection of a daily NVR deposition rate of less than 0.1 ng/sq cm d.
Document ID
19930048510
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bowers, William D. (NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Chuan, R. L. (Femtometrics Costa Mesa, CA, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Optical system contamination: Effects, measurement, control III; Proceedings of the Meeting, San Diego, CA, July 23, 24, 1992 (A93-32476 12-19)
Publisher: Society of Photo-Optical Instrumentation Engineers