Light scattering by dust particles in microgravity: polarization and brightness imaging with the new version of the PROGRA2 instrument

Renard, Jean‐Baptiste; Worms, Jean-Claude; Lemaire, T.; Hadamcik, Edith; Huret, Nathalie

doi:10.1364/ao.41.000609

Cited by 50 publications

(18 citation statements)

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“…l). It uses a statistical approach for the size and concentration retrievals, as is done for the laboratory PROGRA2 instruments dedicated to the study of optical properties of irregular levitating grains (Renard et al, 2002). Because of their shape, their orientation and their rotation in the air flow, the scattering properties of an individual grain vary with time at a given scattering angle (this variation could be more than a factor of 2, as shown during laboratory tests by photodiodes and imagery measurements with PROGRA2).…”

Section: Instrument Conceptmentioning

confidence: 99%

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

et al. 2016

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Abstract. The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12 • , and is almost insensitive to the refractive index of the particles; the second one is around 60 • and is strongly sensitive to the refractive Published by Copernicus Publications on behalf of the European Geosciences Union. J.-B. Renard et al.: Size distribution and nature of atmospheric particlesindex of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20 % when concentrations are higher than 1 particle cm −3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60 % for concentrations smaller than 10 −2 particle cm −3 . Also, the uncertainties in size calibration are ±0.025 µm for particles smaller than 0.6 µm, 5 % for particles in the 0.7-2 µm range, and 10 % for particles greater than 2 µm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles > 3 µm exceeds a few particles cm −3 . Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations.

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Section: Instrument Conceptmentioning

confidence: 99%

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

et al. 2016

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“…For levitating particles, detection is achieved by two CCD cameras recording the light scattered by the dust (two perpendicular directions of polarization). More details on the instrument can be found in Renard et al (2002). Retrieval of polarization values for particles (large grains or aggregates) is done automatically in each image.…”

Section: Instrumentsmentioning

confidence: 99%

“…PROGRA 2 experiment measures brightness and polarization phase functions of dust clouds under microgravity conditions in parabolic flights (Worms et al, 1999;Renard et al, 2002), of fluffy particles lifted by an air-draught (Hadamcik et al, 2002a) and of deposited particles as, e.g., regoliths analogs (Worms et al, 2000). The large number of polarization phase curves already obtained in the various conditions of measurements, in order to build a database (about 160 curves for 100 samples) allows us to better connect the physical properties with the observed polarization of the light scattered by the clouds.…”

Section: Introductionmentioning

confidence: 99%

PROGRA2 experiment: New results for dust clouds and regoliths analogs

Hadamcik¹,

Renard

Levasseur-Regourd³

et al. 2006

Advances in Space Research

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“…The experiment produces tholins in the gas phase as dust particles, or as thin films on substrates. The linear polarization P of the light scattered by the dust particles is measured with the PROGRA 2 instrument (see Renard et al, 2002, for further description). P depends on the geometry of observations, which is expressed by the phase angle α (the angle between the direction of the incident light and the line of sight of the detector, as seen from the dust particle), on the morphology and size distribution of the particles.…”

Section: Introductionmentioning

confidence: 99%

Optical properties of analogs of Titan’s aerosols produced by dusty plasma

et al. 2013

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Analogs of Titan's aerosols are produced in the laboratory as grains in a gas mixture, or as layers on a substrate. This production procedure enables the methane-nitrogen mixture composition to be changed. The aim of this paper is to understand the variations observed on the linear polarization of the scattered light as a function of the production conditions. The influence of the concentration of methane injected in the plasma will be discussed and compared with the previous work of Hadamcik et al. (2009a). The diameter of the grains are measured by SEM-FEG images. The decrease of absorption with increasing wavelength, measured by spectroscopic ellipsometry on layers, is observed for a decreasing initial methane ratio and analyzed in terms of an increasing 'amine' content in the materials. The phase function parameters of the linear polarization of the scattered light are discussed in terms of the diameters of the aggregates and of the constituent grains, and the variation of the refractive indices (mainly absorption). The polarization is found to be highly correlated with the constituent grain size. Finally, the experimental results are compared to polarization measurements from space of the Titan's atmosphere.

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Light scattering by dust particles in microgravity: polarization and brightness imaging with the new version of the PROGRA2 instrument

Cited by 50 publications

References 4 publications

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

PROGRA2 experiment: New results for dust clouds and regoliths analogs

Optical properties of analogs of Titan’s aerosols produced by dusty plasma

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