A Compact, Low-power Spectrometer For Atmospheric Particle Measurements
Abstract
A compact, lightweight and relatively robust aerosol spectrometer is under develop- ment for use in a variety of atmospheric particle investigations. This instrument will cover particle sizes in the range from 0.3 to 10µm with a weight of around 0.5kg (depending upon configuration). The low weight and compact size will make this de- vice suitable for balloon-borne atmospheric measurements, and its relatively low cost will encourage deployment in riskier situations, such as close to the ocean surface. The reasonably high volume sampling rate of approximately 50ml/s commends it to applications where high temporal resolution is required such as in particle flux studies.
This instrument is based around a small scatter cell unit, measuring approximately 7 x 3 x 3cm, manufactured by Met One (a division of Pacific Scientific). This unit incor- porates a circuit board with solid state laser supply, detector and signal preamplifiers and is built into a number of Met One particle counters which, in their smaller in- struments, generally have only two size channels. Additional circuit boards have been designed and developed in Leeds which, in addition to appropriate control, data stor- age and transmission electronics, contain a multi-channel pulse height analyser. Laser scattering instruments generally exhibit a multi-valued response for particles around the wavelength of the laser illumination, the precise location of which depends upon the refractive index (and hence the composition) of the particulate material. By using a 12-bit A/D converter and full microprocessor control, the operating performance of the instrument may be optimised for particles with differing characteristics, with an output resolution of up to 256 size channels. The prototype is being evaluated and the degree to which its sensitivity and volume sampling rate may be adjusted to extend its operating size range examined. The low- cost and compact dimensions of these instruments allow risks to be taken in their deployment, which would not be practicable with larger aerosol instruments. Further- more, their relatively high volume flow rate means that, in many applications, particle counting statistics will be adequate to permit data sampling at frequencies up to 10Hz, making them well-suited to aerosol flux studies.- Publication:
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EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.4391S