scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2019 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation causing changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically-oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights on the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on particles can help explain the transport of unexpectedly larger particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modelling results indicate that electrostatic forces should be considered when determining the effect of atmospheric dust on the climate.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2020 ◽  
Vol 20 (5) ◽  
pp. 3181-3190 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation and causes changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights into the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on charged particles can help explain the transport of unexpectedly large particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modeling results indicate that electrostatic forces may in some cases be relevant regarding the effect of atmospheric dust on the climate.

Electrostatic Forces on Particles Floating Within the Interface Between Two Immiscible Fluids

2007 ◽  
Author(s):  
Nadine Aubry ◽  
Pushpendra Singh
Keyword(s):  
Dielectric Properties ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
External Electric Field ◽  
Capillary Force ◽  
Electrostatic Force ◽  
Immiscible Fluids ◽  
Electrostatic Forces ◽  
Dipole Interactions

The objective of this paper is to study the dependence of the electrostatic force that act on a particle within the interface between two immiscible fluids on the parameters such as the dielectric properties of the fluids and particles, the particle’s position within the interface, and the electric field strength. It is shown that the component of electrostatic force normal to the interface varies as a2, where a is the particle radius, and since in equilibrium it is balanced by the vertical capillary force, the interfacial deformation caused by the particle changes when an external electric field is applied. In addition, there are lateral electrostatic forces among the particles due to the dipole-dipole interactions which, when the distance between two particles is O(a), vary as a2, and remain significant for submicron sized particles.

scholarly journals The Adhesion of Ice Spheres in Electric Fields

1967 ◽  
Vol 6 (46) ◽  
pp. 505-514 ◽  
Author(s):  
J. Latham ◽  
C. P. R. Saunders
Keyword(s):  
Relative Humidity ◽  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Environmental Temperature ◽  
Ice Crystal ◽  
Electrostatic Forces ◽  
Rate Of Growth ◽  
Crystal Aggregation

AbstractThe forceFrequired to separate two ice spheres was measured as a function of environmental temperatureT, relative humidityHand the strengthEof the external electric field in which the spheres were situated. It was found that over the entire attainable range ofTandH,Fincreased rapidly with increasingE. The increased adhesion was not accompanied by an increase in the rate of growth of the ice bridge between the two spheres and is explicable in terms of Davis’s (1964) calculations of the purely electrostatic forces between two spheres situated in an electric field. The experiments indicate that the rate of growth of snowflakes in a cloud by means of ice crystal aggregation will be markedly enhanced if the cloud is highly electrified.

scholarly journals Reinterpretation of Electric Field with Quantum Fluctuations: The Mechanism of Electrostatic Force of Attraction and Repulsion Between Two Point Charges

2020 ◽  
pp. 28-33
Author(s):  
C. G. Sim
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Vacuum Polarization ◽  
Quantum Fluctuation ◽  
Casimir Effect ◽  
Electrostatic Force ◽  
Quantum Fluctuations ◽  
Repulsive Force ◽  
Fluctuation Energy ◽  
Virtual Pairs

Vacuum polarization rearranges virtual  pairs. This causes the virtual  pairs to rigidify in vacuum, reducing the quantum fluctuation energy. The quantum fluctuation energy is a fundamental force of vacuum, as evidenced by the Casimir effect. The change in quantum fluctuation energy was simulated in the superposition of the electric fields. The results show that the increase and decrease of the quantum fluctuation energy between the two point charges is related to the repulsive force and attraction in Coulomb's law.

On the occurrence and characteristics of intense low-altitude electric fields observed by Freja

1995 ◽  
Vol 13 (7) ◽  
pp. 704-712 ◽  
Author(s):  
G. Marklund ◽  
L. Blomberg ◽  
C.-G. Fälthammar ◽  
P.-A. Lindqvist ◽  
L. Eliasson
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Early Morning ◽  
Auroral Oval ◽  
Small Scale ◽  
Auroral Region ◽  
Ion Heating ◽  
Intense Fields ◽  
Auroral Emissions ◽  
Auroral Arcs

Abstract. High-resolution measurements by the double probe electric field instrument on the Freja satellite are presented. The observations show that extremely intense (up to 1 V m–1) and fine-structured (<1 km) electric fields exist at auroral latitudes within the altitude regime explored by Freja (up to 1700 km). The intense field events typically occur within the early morning sector of the auroral oval (01–07 MLT) during times of geomagnetic activity. In contrast to the observations within the auroral acceleration region characterized by intense converging electric fields associated with electron precipitation, upward ion beams and upward field-aligned currents, the intense electric fields observed by Freja are often found to be diverging and located within regions of downward field-aligned currents outside the electron aurora. Moreover, the intense fields are observed in conjunction with precipitating and transversely energized ions of energies 0.5–1 keV and may play an important role in the ion heating. The observations suggest that the intense electric field events are associated with small-scale low-conductivity ionospheric regions void of auroral emissions such as east-west aligned dark filaments or vortex streets of black auroral curls located between or adjacent to auroral arcs within the morningside diffuse auroral region. We suggest that these intense fields also exist at ionospheric altitudes although no such observations have yet been made. This is possible since the height-integrated conductivity associated with the dark filaments may be as low as 0.1 S or less. In addition, Freja electric field data collected outside the auroral region are discussed with particular emphasis on subauroral electric fields which are observed within the 19–01 MLT sector between the equatorward edge of the auroral oval and the inner edge of the ring current.

scholarly journals The Adhesion of Ice Spheres in Electric Fields

1967 ◽  
Vol 6 (46) ◽  
pp. 505-514
Author(s):  
J. Latham ◽  
C. P. R. Saunders
Keyword(s):  
Relative Humidity ◽  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Environmental Temperature ◽  
Ice Crystal ◽  
Electrostatic Forces ◽  
Rate Of Growth ◽  
Crystal Aggregation

AbstractThe force F required to separate two ice spheres was measured as a function of environmental temperature T, relative humidity H and the strength E of the external electric field in which the spheres were situated. It was found that over the entire attainable range of T and H, F increased rapidly with increasing E. The increased adhesion was not accompanied by an increase in the rate of growth of the ice bridge between the two spheres and is explicable in terms of Davis’s (1964) calculations of the purely electrostatic forces between two spheres situated in an electric field. The experiments indicate that the rate of growth of snowflakes in a cloud by means of ice crystal aggregation will be markedly enhanced if the cloud is highly electrified.

scholarly journals Polarisation of a small-scale cometary plasma environment

2019 ◽  
Vol 631 ◽  
pp. A174 ◽  
Author(s):  
Herbert Gunell ◽  
Jesper Lindkvist ◽  
Charlotte Goetz ◽  
Hans Nilsson ◽  
Maria Hamrin
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Space Charge ◽  
Electric Fields ◽  
Cell Model ◽  
Small Scale ◽  
Space Charge Effects ◽  
Density Maximum ◽  
Polarisation Field ◽  
Charge Effects

Context. The plasma near the nucleus of a comet is subjected to an electric field to which a few different sources contribute: the convective electric field of the solar wind, the ambipolar electric field due to higher electron than ion speeds, and a polarisation field arising from the vastly different ion and electron trajectories. Aims. Our aim is to show how the ambipolar and polarisation electric fields arise and develop under the influence of space charge effects, and in doing so we paint a qualitative picture of the electric fields in the inner coma of a comet. Methods. We use an electrostatic particle-in-cell model to simulate a scaled-down comet, representing comet 67P/Churyumov-Gerasimenko with parameters corresponding to a 3.0 AU heliocentric distance. Results. We find that an ambipolar electric field develops early in the simulation and that this is soon followed by the emergence of a polarisation electric field, manifesting itself as an anti-sunward component prevalent in the region surrounding the centre of the comet. As plasma is removed from the inner coma in the direction of the convectional electric field of the solar wind, a density maximum develops on the opposite side of the centre of the comet. Conclusions. The ambipolar and polarisation electric fields both have a significant influence on the motion of cometary ions. This demonstrates the importance of space charge effects in comet plasma physics.

scholarly journals On the ionospheric coupling of auroral electric fields

2009 ◽  
Vol 16 (2) ◽  
pp. 365-372 ◽  
Author(s):  
G. T. Marklund
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Small Scale ◽  
Scale Size ◽  
Current Voltage ◽  
Current Region ◽  
Scale Structures ◽  
Downward Currents ◽  
Current Voltage Relation ◽  
Small Scale Structures

Abstract. The quasi-static coupling of high-altitude potential structures and electric fields to the ionosphere is discussed with particular focus on the downward field-aligned current (FAC) region. Results are presented from a preliminary analysis of a selection of electric field events observed by Cluster above the acceleration region. The degree of coupling is here estimated as the ratio between the magnetic field-aligned potential drop, ΔΦII, as inferred from the characteristic energy of upward ion (electron) beams for the upward (downward) current region and the high-altitude perpendicular (to B) potential, ΔΦbot, as calculated by integrating the perpendicular electric field across the structure. For upward currents, the coupling can be expressed analytically, using the linear current-voltage relation, as outlined by Weimer et al. (1985). This gives a scale size dependent coupling where structures are coupled (decoupled) above (below) a critical scale size. For downward currents, the current-voltage relation is highly non-linear which complicates the understanding of how the coupling works. Results from this experimental study indicate that small-scale structures are decoupled, similar to small-scale structures in the upward current region. There are, however, exceptions to this rule as illustrated by Cluster results of small-scale intense electric fields, correlated with downward currents, indicating a perfect coupling between the ionosphere and Cluster altitude.

scholarly journals Parallel electric field in the auroral ionosphere: excitation of acoustic waves by Alfvén waves

2004 ◽  
Vol 22 (8) ◽  
pp. 2797-2804 ◽  
Author(s):  
P. L. Israelevich ◽  
L. Ofman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Acoustic Waves ◽  
Finite Amplitude ◽  
Alfven Waves ◽  
Plasma Pressure ◽  
Alfvén Waves ◽  
Small Scale ◽  
Auroral Ionosphere ◽  
Parallel Electric Field

Abstract. We investigate a new mechanism for the formation of a parallel electric field observed in the auroral ionosphere. For this purpose, the excitation of acoustic waves by propagating Alfvén waves was studied numerically. We find that the magnetic pressure perturbation due to finite amplitude Alfvén waves causes the perturbation of the plasma pressure that propagates in the form of acoustic waves, and gives rise to a parallel electric field. This mechanism explains the observations of the strong parallel electric field in the small-scale electromagnetic perturbations of the auroral ionosphere. For the cases when the parallel electric current in the small-scale auroral perturbations is so strong that the velocity of current carriers exceeds the threshold of the ion sound instability, the excited ion acoustic waves may account for the parallel electric fields as strong as tens of mV/m.

Effect of Inlet Tangential Port Area on Droplet Size Distribution of Small-Scale Simplex Atomizer

2013 ◽  
Author(s):  
Muthu Selvan Govindaraj ◽  
Muralidhara H. Suryanarayana Rao ◽  
Vinod Kumar Vyas ◽  
Karthy Shanmugasundaram ◽  
Narendran Venugopal ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Flow Direction ◽  
Injection Pressure ◽  
Droplet Size Distribution ◽  
Working Fluid ◽  
Small Scale ◽  
Size Distributions ◽  
Port Area ◽  
Droplet Size Distributions

An experimental investigation was conducted to study the effects of increased area of inlet tangential ports on the droplet size distribution of small-scale simplex atomizer. The spray characteristics of four different simplex atomizers representing increasing area of inlet tangential ports (diameter range 0.6 mm to 0.9 mm) are examined using water as working fluid. Measurements of droplet size and droplet size distributions of the four different atomizer configurations were carried using Malvern droplet size instrument at various downstream locations from final orifice exit. These measurments has been taken for five different injection pressures of spray. Variation of droplet size and droplet size distribution along the flow direction of spray was examined. The effect of increase in injection pressure on droplet size distribution of the spray was examined. Increase in inlet tangential port area significantly affects droplet size and droplet size distributions of the spray and affects the length of primary breakup region.

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