Maxwell–Wagner relaxation in common minerals and a desert soil at low water contents

Arcone, Steven A.; Boitnott, Ginger

doi:10.1016/j.jappgeo.2011.09.005

Cited by 19 publications

(15 citation statements)

References 32 publications

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“…In earlier work based on time-domain reflectometry (TDR) measurements, we concluded that the anomalously high GPR attenuation rates found in some arid-zone soils were caused by Maxwell-Wagner-Sillars (MWS) polarization [2], [3]. Our ability to quantify the complex dielectric behavior of arid zone soils suggestive of MWS polarization had been limited.…”

Section: Introductionmentioning

confidence: 98%

“…where w is angular frequency (= 27rv, rad·s-I ) and Co, speed of light (m·s-I ) [2]. If the complex relative permittivity of a soil is measured or can be predicted, the attenuation rate can be calculated directly from equation (2).…”

Section: Introductionmentioning

confidence: 99%

“…If the complex relative permittivity of a soil is measured or can be predicted, the attenuation rate can be calculated directly from equation (2). Analyses of soil permittivity data have led to a general conclusion that the dielectric permittivity of soils at low volumetric water contents will be close to those of the mineral phases and the influence of water is limited [I].…”

Section: Introductionmentioning

confidence: 99%

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Maxwell-wagner-sillars, adsorbed water, and free-water dielectric relaxations within a hydrated arid-zone calcic soil

Grant¹,

Arcone²,

Boitnott³

2014

Proceedings of the 15th International Conference on Ground Penetrating Radar

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Abstract-We measured the broadband (40 Hz-20 GHz) rel ative dielectric permittivity of sieved surficial samples of an arid-zone soil. The soil samples were equilibrated at 25°C with relative humidities of 43, 54, 84, and 97 %. Debye-like Maxwell-Wagner-Sillars (MWS) polarization relaxation times of 309, 227, and 73 ns were calculated for the soil samples equili brated at relative humidities of 43, 54, and 84 %, respectively.Due to electrode polarization, MWS polarization relaxations could be not be discerned on the soil sample equilibrated at 97 % relative humidity. The measured differences between the static and high-frequency relative permittivity (Es -Eoo ) due to MWS polarization were between 25 and 45 times that of the oven dry soil. This would cause the MWS relaxation to increase radar-wave attenuation rates at frequencies as high as 1 GHz.We found Debye-type relaxation times associated with adsorbed water of 13, 15, 17, 19, and 22 ps for an oven-dry sample and ones equilibrated at at relative humidities of 43, 54, 84, and 97 %, respectively. These frequencies are higher than previously thought. This progression with water contents may be due to the increase in soil solution salinity with increasing water contents.They were not likely caused by free water since a weakly resolved relaxation could be discerned corresponding to a relaxation time of approximately 8 ps, as expected for free-water.Index Terms-Adsorbed water, dielectric permittivity, free water, Maxwell-Wagner-Sillars polarization, dielectric relaxation, soil. I. I NTRODUCTIONIn earlier work based on time-domain reflectometry (TDR) measurements, we concluded that the anomalously high GPR attenuation rates found in some arid-zone soils were caused by Maxwell-Wagner-Sillars (MWS) polarization [2], [3]. Our ability to quantify the complex dielectric behavior of arid zone soils suggestive of MWS polarization had been limited. This was because some of these TDR measurements were subject to electrode-polarization effects at frequencies below I MHz. Because the apparent relaxation frequency of MWS polarization was in this frequency range, we were compelled to estimate relaxation parameters with modeling results, which may have introduced extrapolation error in these estimates.We report here broadband dielectric measurements made at low frequencies with a dielectric cell fitted to an impedance analyzer and at high frequencies with an open-ended coaxial probe fitted to a vector network analyzer. This approach extended the bandwidth and improved the precision over what could be achieved with TDR measurements. This composite approach should also provide more accurate estimates of attenuation rate over the entire GPR bandwidth. For most measurements it also shifted the onset frequency of electrode polarization far below that of the MWS, which allowed us to estimate relaxation parameters by non-linear regression fits to a simple Debye-type expression. The complex relative dielectric permittivity of a soil can

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Maxwell-wagner-sillars, adsorbed water, and free-water dielectric relaxations within a hydrated arid-zone calcic soil

Grant¹,

Arcone²,

Boitnott³

2014

Proceedings of the 15th International Conference on Ground Penetrating Radar

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“…We think that because the silt is not deeply frozen, there is adsorbed water on the silt and clay particle surfaces. This dispersed water causes Maxwell-Wagner relaxation (Arcone and Boitnott 2012), whereby discrete pockets of conductive material act as macrodipoles that cannot stay in phase with the applied field. Consequently, wave energy is converted into heat and conductive currents.…”

Section: Old Steese Highwaymentioning

confidence: 99%

Ground-Penetrating-Radar Profiles of Interior Alaska Highways: Interpretation of Stratified Fill, Frost Depths, Water Table, and Thaw Settlement over Ice-Rich Permafrost

Arcone¹,

Bjella²

2016

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In early spring 2014, we recorded ground-penetrating-radar (GPR) profiles along several highways in interior Alaska to determine present and potential damaging thaw settlement, which could help site and design infrastructure in permafrost terrains. We used GPR pulses centered near 100, 150, and 320 MHz. Comparative profiles of electrical resistivity, historical GPR profiles, and limited borehole information aided interpretations. Beneath the Elliott Highway, Goldstream Road, and the Old Steese Highway, construction fill was recognized by its stratification; and frost depth and water-table horizons were recognized by phase attributes of the reflected pulse, as dictated by dielectric permittivity contrasts, relative depths, and continuity. Undulating fill stratification indicated thaw settlement, caused by melting of buried ice. We interpreted various stratigraphic folds to represent cases of active, recent, remediated and historical settlement. A section along the Tok Cutoff Road revealed the top and bottom of massive ice within glacial moraine. Signal penetration was greatly reduced beneath the water table, and the permafrost table was not detected. This information is valuable for highway maintenance and planning of new construction, especially in remote locations where information on permafrost and ice features are limited.

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“…Maxwell-Wagner interfacial relaxations (MWR, [I]) are generally centered within the 1-20 MHz range of complex relative permittivity spectra, fi", of moist soils [2,3]. For fine-grained soils with volumetric water contents less than about 10% MWR can significantly add to attenuation rates within the ground-penetrating radar (GPR) bandwidth of 100-1000 MHz.…”

Section: Introductionmentioning

confidence: 99%

Broadband TDR permittivity spectra of lossy soils at medium to high water contents: Separation of electrode polarization from Maxwell-Wagner relaxation by modeling

Arcone

Grant

Boitnott

2014

Proceedings of the 15th International Conference on Ground Penetrating Radar

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We discuss complex permittivity spectra of two lossy soils measured from 6 kHz to 6 GHz using time domain reflectometry, in which Maxwell-Wagner relaxation (MWR) is present but also unwanted electrode polarization EP, mainly below 1 MHz, is strong. The soils are mostly quartz, with one having lesser calcite and the other lesser gypsum. Volumetric water contents ranged from 8.5-30.9%. We use a simple model that adds an EP diffusion term to Debye type terms for the MWR and free water relaxation centered near 19 GHz, and which allows us to separate the EP from the MWR. All samples show MWRs centered from 1-196 MHz, regardless of water content, and with small to significant Cole-Cole factors. The increasing water content diminishes the effect of MWR, likely by decreasing the conductive and dielectric contrasts between isolated inclusions and the soil matrix, but still can strongly contribute to attenuation rate across the 100-1000 MHz GPR bandwidth.

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Maxwell–Wagner relaxation in common minerals and a desert soil at low water contents

Cited by 19 publications

References 32 publications

Maxwell-wagner-sillars, adsorbed water, and free-water dielectric relaxations within a hydrated arid-zone calcic soil

Maxwell-wagner-sillars, adsorbed water, and free-water dielectric relaxations within a hydrated arid-zone calcic soil

Ground-Penetrating-Radar Profiles of Interior Alaska Highways: Interpretation of Stratified Fill, Frost Depths, Water Table, and Thaw Settlement over Ice-Rich Permafrost

Broadband TDR permittivity spectra of lossy soils at medium to high water contents: Separation of electrode polarization from Maxwell-Wagner relaxation by modeling

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