9362015 Buck Measurement of trace amounts of water vapor is critical to industrial processes such as semiconductor fabrication, where moisture in gases must often be below a few parts per billion (PPB). Water in trace amounts is also critical in high altitude atmospheric chemistry, affecting global climate change and ozone depletion. Current instruments for measuring trace moisture are severely limited. Some cannot maintain calibration; others have slow response times. Most have limited sensitivity. A cryogenic chilled-mirror hygrometer capable of extremely high sensitivity (below one PPB) and very fast response time (a few seconds) has been developed. It is accurate and simple to operate. However, to be fully useful in industrial processes, the relationship between dew/frost point and vapor pressure (enhancement factor) must be defined for industrial gases. This instrument provides direct means to determine enhancement factors at very low moisture levels in a variety of gases. This research is to test and optimize the instrument for use as a trace moisture sensor in industrial gases. This work will make possible fast, accurate measurements of trace water vapor in industrial gases and the atmosphere.
