Project Title:
An Open Path Diode Laser Flux Meter for Trace Gases
12.06-9500
An Open Path Diode Laser Flux Meter for Trace Gases
Aerodyne Research Inc.
45 Manning Road
Billerica
MA
01821
Stanton
Alan C.
NAS2-12433
Amount:
ARC
NAS2-12117
Abstract:
The purpose of this study is the development of instrumentation to measurefluxes of trace gases in order to determine their sources and sinks in the biosphere.
A tunable diode laser source combined with an open path multiple pass absorption
cell is used for trace species detection at sub-ppb levels. Absorption lines for
sensitive, interference-free atmospheric pressure detection of important trace gases
have been identified. Laboratory tests, including measurements of atmospheric nitrous
oxide at atmospheric pressure, demonstrated the feasibility of the multiple pass
diode laser approach. Preliminary evaluations of alternative cell designs and data
processing techniques have also been performed.
Phase II, an open path tunable diode laser monitor of trace gases will be interfaced
with a sonic anemometer and thermistor temperature sensor to permit simultaneous
measurements of trace species concentration, temperature, and fluctuating velocity
field. These measurements will be correlated to obtain fluxes of at least four trace
species, possibly including nitrous oxide,
methane, carbon monoxide, carbon dioxide, ammonia, carbonyl sulfide, or carbon disulfide.
The result will be a prototype instrument which will be delivered to NASA and tested
in field measurements of trace species fluxes.