Aerodyne Research mobile infrared methane monitorAn improved real-time methane monitor based on infrared absorption of the 3.39 micron line of a HeNe laser is described. Real time in situ measurement of methane has important applications in stratospheric and tropospheric chemistry, especially when high accuracy measurements can be made rapidly, providing fine spatial-scale information. The methane instrument provides 5 ppb resolution in a 1 sec averaging time. A key feature in this instrument is the use of magnetic (Zeeman) broadening to achieve continuous tunability with constant output power over a range of 0.017/cm. The instruments optical absorption path length is 47 m through sampled air held at 50 torr in a multipass cell of the Herriott (off-axis resonator) type. A microprocessor controls laser frequency and amplitude and collects data with minimal operator attention. The instrument recently has been used to measure methane emissions from a variety of natural and artificial terrestrial sources.
Document ID
19920069550
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Mcmanus, J. B. (NASA Headquarters Washington, DC United States)
Kebabian, P. L. (NASA Headquarters Washington, DC United States)
Kolb, C. E. (Aerodyne Research, Inc. Center for Chemical and Environmental Physics, Billerica, MA, United States)