A 3D Time-Dependent Model for the Study of the Electrification of Non Spherical Dust Particles due to Ion Attachment

2020 ◽  
Author(s):  
Sotirios Mallios ◽  
Vasiliki Daskalopoulou ◽  
Evangelos Skoubris ◽  
George Hloupis ◽  
Athanasios Papaioannou ◽  
...  
Keyword(s):  
Electric Field ◽  
Dust Cloud ◽  
Dust Particles ◽  
Dust Layer ◽  
The Past ◽  
Dependent Model ◽  
Ion Attachment ◽  
Atmospheric Conductivity ◽  
Time Dependent Model ◽  
Positively Charged

<p>Electrical processes can be a potential key player in the lifecycle of desert dust. The dust particles can be charged during their transport, either by the attachment of atmospheric ions or by particle to particle collisions (triboelectric effect). Measurements indicate that, on average, larger particles become positively charged while the smaller ones become negatively charged [<em>Zhao, H. L.</em>, J. Electrostat, 55, 2002; <em>Lacks, D.J.</em>, et al., Phys. Rev. Lett., 100, 188305, 2008; <em>Merrison, J.P.</em>, Aeolian Res., 4, 2012; <em>Shinbrot, T. and Herrmann, H.J.</em>, Nature, 451, 2008]. During dust transportation, the larger and mainly positively charged particles separate from the smaller negatively charged particles due to the gravitational sedimentation, which sorts the dust particles by size. This process develops vertical electric fields within the dust cloud, enhancing the pre-existing field due to the depletion of atmospheric conductivity by the presence of the dust layer [<em>Gringel W. and Mulheisen. R.</em>, Beitr. Phys. Atmos., 51, 121–8, 1978]. Depending on its strength, the total electric field within the dust cloud can: (a) counteract the gravitational settling of large particles and (b) cause a preferential orientation of the non-spherical particles along the vertical direction affecting particle aerodynamics [<em>Ulanowski, Z., et al.</em>, Atmos. Chem. Phys., 7, 2007]. Therefore, electrical processes may alter dust removal processes, and thus the evolution of particle size during transport, affecting dust-radiation-cloud interactions and the associated air quality [<em>Sajani S.Z., et al.</em>, Occup. Environ. Med., 68(6), 2011], weather, and climate modeling [<em>Mahowald, N., et al.</em>, Aeolian Res., 15, 2014].</p><p>In the present work, we have developed a novel 3D Cartesian time-dependent model that takes into account several atmospheric processes, such as: (i) the ionization due to the galactic cosmic rays radiation, (ii) the ion-ion recombination, and (iii) the ion attachment to non spherical dust particles.  The model is able to self-consistently calculate the time dynamics of the atmospheric conductivity, and the atmospheric electric field, under the presence of a distribution of stationary non spherical dust particles. Additionally, the total charge density, dust particle charge and dust particle orientation are also quantified. The new 3D electrification formalism allows the study of dust layers without imposing any symmetry and  is valid for layers with any horizontal and vertical extend, as opposed to 1D models which are valid when the horizontal extend is much larger than the vertical, or to 2D models which assume a symmetry in the shape of the dust layer. The results are compared, in the limiting case that the horizontal extend is much larger than the vertical one, with those obtained from 1D models found in the past literature [e.g. <em>Zhou, L., Tinsley, B.A.</em>, Adv. Space Res. 50, 2012]. Moreover, the effect of the studied electrification process is assessed through a comparison with recent and unique electric field measurements within lofted dust layers, as performed with the use of novel low cost atmospheric electricity sensors in an experimental campaign of the D-TECT ERC project, in Cyprus the past November.</p>

scholarly journals Modeling of Spherical Dust Particle Charging due to Ion Attachment

2021 ◽  
Vol 9 ◽  
Author(s):  
Sotirios A. Mallios ◽  
Georgios Papangelis ◽  
George Hloupis ◽  
Athanasios Papaioannou ◽  
Vasiliki Daskalopoulou ◽  
...  
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Negative Ions ◽  
Particle Dynamics ◽  
Electrical Charge ◽  
Dust Particles ◽  
Electrical Force ◽  
Force Magnitude ◽  
Ion Attachment ◽  
The Impact

The attachment of positive and negative ions to settling spherical dust particles is studied. A novel 1D numerical model has been developed to parameterize the charging process in the presence of a large-scale electric field. The model is able to self-consistently calculate the modification of atmospheric ion densities in the presence of the dust particles, and the consequent alteration of the atmospheric electrical conductivity and the large-scale electric field. Moreover, the model estimates the acquired electrical charge on the dust particles and calculates the electrical force that is applied on them. Using observed dust size distributions, we find that the particles can acquire electrical charge in the range of 1–1,000 elementary charges depending on their size and number density. The particles become mainly negatively charged, but under specific conditions giant mode particles (larger than 50 μm radius) can be positive. Moreover, the large-scale electric field can increase up to 20 times as much as the fair weather value. However, our approach shows that the resultant electrical force is not enough to significantly influence their gravitational settling, as the ratio between the electrical force magnitude and the gravity magnitude does not exceed the value of 0.01. This indicates that the process of ion attachment alone is not sufficient to create strong electrical effects for the modification of particle dynamics. Therefore, other processes, such as the triboelectric effect and updrafts, must be included in the model to fully represent the impact of electricity on particle dynamics.

scholarly journals Alignment of atmospheric mineral dust due to electric field

2007 ◽  
Vol 7 (24) ◽  
pp. 6161-6173 ◽  
Author(s):  
Z. Ulanowski ◽  
J. Bailey ◽  
P. W. Lucas ◽  
J. H. Hough ◽  
E. Hirst
Keyword(s):  
Electric Field ◽  
Vertical Direction ◽  
Saharan Dust ◽  
Particle Orientation ◽  
Dust Layer ◽  
Dust Transport ◽  
La Palma ◽  
Partial Alignment ◽  
Vertically Aligned ◽  
Atmospheric Conductivity

Abstract. Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction indicating the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here. It is also possible that the alignment and the electric field modify dust transport.

scholarly journals On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

2007 ◽  
Vol 25 (3) ◽  
pp. 623-637 ◽  
Author(s):  
O. Havnes ◽  
L. I. Næsheim
Keyword(s):  
Grazing Incidence ◽  
Dust Particles ◽  
Bottom Plate ◽  
Charged Dust ◽  
Dust Layer ◽  
Secondary Currents ◽  
Positive Currents ◽  
The Impact ◽  
The Relationship ◽  
Positively Charged

Abstract. The dust probe DUSTY, first launched during the summer of 1994 (flights ECT–02 and ECT–07) from Andøya Rocket Range, northern Norway, was the first probe to unambiguously detect heavy charged mesospheric aerosols, from hereon referred to as dust. In ECT–02 the probe detected negatively charged dust particles in the height interval of 83 to 88.5 km. In this flight, the lower grid in the detector (Grid 2) measures both positive and negative currents in various regions, and we find that the relationship between the current measurements of Grid 2 and the bottom plate can only be explained by influence from secondary charge production on Grid 2. In ECT–07, which had a large coning, positive currents reaching the top grid of the probe were interpreted as due to the impact of positively charged dust particles. We have now reanalyzed the data from ECT–07 and arrived at the conclusion that the measured positive currents to this grid must have been mainly due to secondary charging effects from the impacting dust particles. The grid consists of a set of parallel wires crossed with an identical set of wires on top of it, and we find that if the observed currents were created from the direct impact of charged dust particles, then they should be very weakly modulated at four times the rocket spin rate ωR. Observations show, however, that the observed currents are strongly modulated at 2ωR. We cannot reproduce the observed large modulations of the impact currents in the dust layer if the currents are due only to the transfer of the charges on the impacted dust particles. Based on the results of recent ice cluster impact secondary charging experiments by Tomsic (2003), which found that a small fraction of the ice clusters, when impacting with nearly grazing incidence, carried away one negative charge −1e, we have arrived at the conclusion that similar, but significantly more effective, charging effects must be predominantly responsible for the positive currents measured by the top grid in ECT–07 and their large rotational modulation at 2ωR. Since the secondary effect is dependent on the size of the impacting dust, this opens up for the possibility of mapping the relative dust sizes throughout a dust layer by comparing the observed direct and secondary currents.

scholarly journals Alignment of atmospheric mineral dust due to electric field

2007 ◽  
Vol 7 (5) ◽  
pp. 13203-13241 ◽  
Author(s):  
Z. Ulanowski ◽  
J. Bailey ◽  
P. W. Lucas ◽  
J. H. Hough ◽  
E. Hirst
Keyword(s):  
Electric Field ◽  
Optical Thickness ◽  
Vertical Direction ◽  
Saharan Dust ◽  
Particle Orientation ◽  
Dust Layer ◽  
La Palma ◽  
Partial Alignment ◽  
Vertically Aligned ◽  
Atmospheric Conductivity

Abstract. Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction consistent with the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling also indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here.

scholarly journals A predictable smoothing evolution model for computer-controlled polishing

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Jing Hou ◽  
Pengli Lei ◽  
Shiwei Liu ◽  
Xianhua Chen ◽  
Jian Wang ◽  
...  
Keyword(s):  
Evolution Model ◽  
Quantitative Prediction ◽  
Theoretical Support ◽  
Model Combining ◽  
Process Guidance ◽  
Dependent Model ◽  
Computer Controlled Optical Surfacing ◽  
Computer Controlled ◽  
Time Dependent Model ◽  
Selection Of

AbstractQuantitative prediction of the smoothing of mid-spatial frequency errors (MSFE) is urgently needed to realize process guidance for computer controlled optical surfacing (CCOS) rather than a qualitative analysis of the processing results. Consequently, a predictable time-dependent model combining process parameters and an error decreasing factor (EDF) were presented in this paper. The basic smoothing theory, solution method and modification of this model were expounded separately and verified by experiments. The experimental results show that the theoretical predicted curve agrees well with the actual smoothing effect. The smoothing evolution model provides certain theoretical support and guidance for the quantitative prediction and parameter selection of the smoothing of MSFE.

A time-dependent model for high-pressure discharges in narrow ablative capillaries

1993 ◽  
Vol 50 (1) ◽  
pp. 51-70 ◽  
Author(s):  
D. Zoler ◽  
S. Cuperman ◽  
J. Ashkenazy ◽  
M. Caner ◽  
Z. Kaplan
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Time Dependent ◽  
Dimensional Model ◽  
Plasma Sources ◽  
One Dimensional ◽  
Space And Time ◽  
Dependent Model ◽  
Energy Equations ◽  
Time Dependent Model

A time-dependent quasi-one-dimensional model is developed for studying high- pressure discharges in ablative capillaries used, for example, as plasma sources in electrothermal launchers. The main features of the model are (i) consideration of ablation effects in each of the continuity, momentum and energy equations; (ii) use of a non-ideal equation of state; and (iii) consideration of space- and time-dependent ionization.

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