Abstract

In situ measurements of the sizes and concentrations of dust particles generated by the detonation of high explosives in clay soil near Leesville, La., sandy clay soil near Huntsville, Ala., and sandy soils near Orogrande, N.M. are reported. Measurements were generally made within 1 m of the surface (in one case 10 m) at distances ranging from 10 to ~50 m from the detonation point with a combination of Knollenberg light-scattering counters (for particles with equivalent radius in the submicron to 15-μm range) and a Knollenberg optical array probe (for particles of 10–150 μm). Measurements were made for periods of several tens of seconds following detonation. All dust size distributions, irrespective of soil or explosive type, exhibit a bimodal character with mass mean radii of ~7 and 70 μm. Peak aerosol mass loadings inferred from the distributions have values ranging from 0.05 to 10 g gm−3 with the larger mode of particles contributing most to the mass loading. Predictions of dust extinction coefficients at visible (0.55-μm) and IR (10.4-μm) wavelengths were made using the measured size distributions together with estimates of dust refractive indices. These predictions suggest that extinction should be nearly neutral (wavelength independent) in agreement with transmission measurements made during some of the tests. Predicted mass extinction coefficients, under the assumption of dust material density of 2.5 g cm−3, are of the order of 0.05 m2 g−1 at both visible and IR wavelengths. This value is also in good agreement with a test-averaged measured value of 0.03 m3 g−1 (at λ = 10.6 μm) obtained using a short path transmissometer and hi-vol sampler.

© 1983 Optical Society of America

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References

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  1. R. G. Pinnick, H. J. Auvermann, J. Aerosol Sci. 10, 55 (1979).
    [CrossRef]
  2. R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
    [CrossRef]
  3. S. G. Jennings, R. G. Pinnick, H. J. Auvermann, Appl. Opt. 17, 3922 (1978).
    [CrossRef]
  4. D. C. Henley, G. B. Hoidale, J. Acoust. Soc. Am. 54, 437 (1973).
    [CrossRef]
  5. The soil size measurements were supplied by J. Mason of the U.S. Army Waterways Experiment Station.
  6. A. Mugnai, W. J. Wiscombe, J. Atmos. Sci. 37, 1291 (1980).
    [CrossRef]
  7. H. M. Nussenzveig, W. J. Wiscombe, Phys. Rev. Lett. 45, 1490 (1980).
    [CrossRef]
  8. P. Chýlek, J. Opt. Soc. Am. 67, 1348 (1977).
    [CrossRef]
  9. The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).
  10. A. Deepak, M. A. Box, Appl. Opt. 17, 2900 (1978).
    [CrossRef] [PubMed]

1981 (1)

R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
[CrossRef]

1980 (2)

A. Mugnai, W. J. Wiscombe, J. Atmos. Sci. 37, 1291 (1980).
[CrossRef]

H. M. Nussenzveig, W. J. Wiscombe, Phys. Rev. Lett. 45, 1490 (1980).
[CrossRef]

1979 (1)

R. G. Pinnick, H. J. Auvermann, J. Aerosol Sci. 10, 55 (1979).
[CrossRef]

1978 (2)

1977 (1)

1973 (1)

D. C. Henley, G. B. Hoidale, J. Acoust. Soc. Am. 54, 437 (1973).
[CrossRef]

Auvermann, H. J.

R. G. Pinnick, H. J. Auvermann, J. Aerosol Sci. 10, 55 (1979).
[CrossRef]

S. G. Jennings, R. G. Pinnick, H. J. Auvermann, Appl. Opt. 17, 3922 (1978).
[CrossRef]

Box, M. A.

Chýlek, P.

Curcio, J. A.

The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).

Deepak, A.

Duncan, L. D.

R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
[CrossRef]

Garvey, D. M.

R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
[CrossRef]

Gott, C.

The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).

Haught, K. M.

The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).

Henley, D. C.

D. C. Henley, G. B. Hoidale, J. Acoust. Soc. Am. 54, 437 (1973).
[CrossRef]

Hoidale, G. B.

D. C. Henley, G. B. Hoidale, J. Acoust. Soc. Am. 54, 437 (1973).
[CrossRef]

Jennings, S. G.

Mugnai, A.

A. Mugnai, W. J. Wiscombe, J. Atmos. Sci. 37, 1291 (1980).
[CrossRef]

Nussenzveig, H. M.

H. M. Nussenzveig, W. J. Wiscombe, Phys. Rev. Lett. 45, 1490 (1980).
[CrossRef]

Pinnick, R. G.

R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
[CrossRef]

R. G. Pinnick, H. J. Auvermann, J. Aerosol Sci. 10, 55 (1979).
[CrossRef]

S. G. Jennings, R. G. Pinnick, H. J. Auvermann, Appl. Opt. 17, 3922 (1978).
[CrossRef]

Waytko, M. A.

The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).

Wiscombe, W. J.

H. M. Nussenzveig, W. J. Wiscombe, Phys. Rev. Lett. 45, 1490 (1980).
[CrossRef]

A. Mugnai, W. J. Wiscombe, J. Atmos. Sci. 37, 1291 (1980).
[CrossRef]

Appl. Opt. (2)

J. Acoust. Soc. Am. (1)

D. C. Henley, G. B. Hoidale, J. Acoust. Soc. Am. 54, 437 (1973).
[CrossRef]

J. Aerosol Sci. (1)

R. G. Pinnick, H. J. Auvermann, J. Aerosol Sci. 10, 55 (1979).
[CrossRef]

J. Appl. Meteorol. (1)

R. G. Pinnick, D. M. Garvey, L. D. Duncan, J. Appl. Meteorol. 20, 1049 (1981).
[CrossRef]

J. Atmos. Sci. (1)

A. Mugnai, W. J. Wiscombe, J. Atmos. Sci. 37, 1291 (1980).
[CrossRef]

J. Opt. Soc. Am. (1)

Phys. Rev. Lett. (1)

H. M. Nussenzveig, W. J. Wiscombe, Phys. Rev. Lett. 45, 1490 (1980).
[CrossRef]

Other (2)

The transmission measurements were made by J. A. Curcio, K. M. Haught, M. A. Waytko, C. Gott, Naval Research Laboratory; private communication (1982).

The soil size measurements were supplied by J. Mason of the U.S. Army Waterways Experiment Station.

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Figures (12)

Fig. 1
Fig. 1

Experimental setup used to measure airborne particles generated by the detonation of explosives in the Leesville, La. tests. The array of instrumentation is mounted on a portable sled which could be moved close to and downwind from the detonation point between tests.

Fig. 2
Fig. 2

Typical crater left by detonation of an explosive in the Leesville test.

Fig. 3
Fig. 3

Response characteristics of the Knollenberg CSASP-100 light-scattering counter for particles characteristic of soil dust constituents. CSASP response: measured (circles) for nonspherical particles of doublet-shaped polystyrene (refractive index m = 1.592–0i); cubical sodium chloride (m = 1.54–0i; ellipsoidal potassium chlorate (m = 1.409–0i); and slightly nonspherical pollens and spores (puff balls, lycopodium powder, paper mulberry, ragweed sweet vernal, and pecan) (with m = 1.53–0i); and calculated using Mie theory (smooth solid curves) for spheres of equal cross section and refractive index. The envelope indicated by the smooth dashed curves defines an estimate of range of uncertainty in particle size that results for a particular response measurement for particles of unknown shape and refractive index.

Fig. 4
Fig. 4

Explosion debris particulate mass loading vs time for Leesville test D9 (a 122-mm artillery munition buried tangent to the surface and detonated at 15:01 local time at a distance of 32 m from our sampling instrumentation). The masses are shown inferred from measurements made (over 5-sec intervals) with three Knollenberg probes: probe A which detects submicron particles; probe B particles 1–10-μm equivalent radius; and probe C particles 10–150 μm. Thus the graph depicts a cross section of the dust cloud as it is transported through our instrumentation by the local wind field.

Fig. 5
Fig. 5

Explosion debris particle size (differential mass) distributions for tests conducted in clay soils near Leesville, La., sandy clay soil near Huntsville, Ala., and sandy soil near Orogrande, N.M. (Details for these tests are given in Table I.) In spite of the different soil and munition types the distributions have a similar bimodal character approximated by the two lognormal curves shown. The lognormal parameters are: for the small mode, total particle mass M = 0.0159 g m−3, total particle number N = 200 cm−3, geometric mean radius rg = 0.5 μm, geometric standard deviation σg = 2.6, and particulate material density ρ = 2.5 g cm−3; for the large mode, M = 0.049 g m−3, N = 0.07 cm−3, rg = 22.5 μm, σg = 1.87, ρ = 2.5 g cm−3.

Fig. 6
Fig. 6

Comparison of airborne dust size distributions (generated by the detonation of explosives in soils of different types) with particulate size distributions of the parent soils. Only the form of the distributions can be compared, as different normalization factors apply to different data sets. The envelopes for the soil distributions encompass the measured distributions for soil samples taken from the surface down to depths of 50 cm for each site, whereas the envelope for the dust distributions encompasses measurements for all sites. The dust measurements were made with a combination of Knollenberg particle counters and the soil measurements with a combination of wet and dry sieving techniques.5

Fig. 7
Fig. 7

Scanning electron microscope micrographs of explosion debris dust particles collected onto a Nuclepore filter for Leesville test C6 (a 6.8-kg composition-4 high explosive buried at a depth of 61 cm). The filter collection was made at a distance of 14 m from the detonation site. The lower micrograph shows a portion of the upper micrograph at a higher magnification.

Fig. 8
Fig. 8

Optical microscope photograph of particles that became dislodged from the Nuclepore filter of Fig. 7.

Fig. 9
Fig. 9

Micrographs of explosion debris dust particles for Leesville test C3 (a 14.3-kg composition-4 high explosive buried tangent to the surface). Some of the particles are thought not to be of soil origin.

Fig. 10
Fig. 10

Explosion debris dust extinction coefficient vs mass loading for visible (open symbols) and IR (solid symbols) wavelengths. Extinction values were calculated from measured particle size distributions assuming spherical particles with refractive indices m = 1.50–0.0077i (λ = 0.55 μm) and m = 1.7–0.2i (λ = 10.6 μm). (These indices represent a combination of estimated and measured values.) Mass loading values were calculated using measured size distributions and a particulate material density of 2.5 g cm−3. The point marked by the boxed × indicates the value of the Huntsville test-averaged extinction as measured with a short (0.83-m) path CO2 (10.6-μm) transmissometer and the value of the Huntsville test-averaged mass loading determined with hi-vol sampler.

Fig. 11
Fig. 11

Predicted visible vs IR extinction coefficients for explosion debris dust suggesting such clouds should display neutral transmission properties.

Fig. 12
Fig. 12

Measured transmission vs time after detonation for Leesville test D9 corroborating our prediction of nearly neutral transmission properties for explosion debris dust.

Tables (1)

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Table I Explosion Debris Dust Tests

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