NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
A New Optical Aerosol SpectrometerAn optical particle spectrometer capable of measuring aerosol particle size distributions from 0.02 to 100 micrometers has been developed. This instrument combines several optical methods in one, in-situ configuration; it can provide continuous data collection to encompass the wide dynamic size ranges and concentrations found in studies of modeled planetary atmospheres as well as terrestrial air quality research. Currently, the system is incorporated into an eight liter capacity spherical pressure vessel that is appropriate both for flowthrough and for in-situ particle generation. The optical sizing methods include polarization ratio, The scattering, and forward scattering detectors, with illumination from a fiber-coupled, Argon-ion laser. As particle sizes increase above 0.1 micrometer, a customized electronics and software system automatically shifts from polarization to diffraction-based measurements as the angular scattering detectors attain acceptable signal-to-noise ratios. The number concentration detection limits are estimated to be in the part-per-trillion (ppT by volume) range, or roughly 1000 submicron particles per cubic centimeter. Results from static experiments using HFC134A (approved light scattering gas standard), flow-through experiments using sodium chloride (NaCl) and carbon particles, and dynamic 'Tholin' (photochemical produced particles from ultraviolet (UV)-irradiated acetylene and nitrogen) experiments have been obtained. The optical spectrometer data obtained with particles have compared well with particle sizes determined by electron microscopy. The 'Tholin' tests provided real-time size and concentration data as the particles grew from about 30 nanometers to about 0.8 micrometers, with concentrations ranging from ppT to ppB, by volume. Tests are still underway, to better define sizing accuracy and concentration limits, these results will be reported.
Document ID
20020073521
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Fonda, Mark
(NASA Ames Research Center Moffett Field, CA United States)
Malcolmson, Andrew
(Insitec Measurement Systems San Ramon, CA United States)
Bonin, Mike
(Insitec Measurement Systems San Ramon, CA United States)
Stratton, David
(Search for Extraterrestrial Intelligence Inst. Mountain View, CA United States)
Rogers, C. Fred
(Desert Research Inst. Reno, NV United States)
Chang, Sherwood
Date Acquired
August 20, 2013
Publication Date
January 1, 1998
Subject Category
Optics
Meeting Information
Meeting: AAAR Conference
Location: Cincinnati, OH
Country: United States
Start Date: June 21, 1998
Funding Number(s)
CONTRACT_GRANT: NAS2-14073
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

There are no available downloads for this record.
No Preview Available