Quasi‐electrostatic field analysis and simulation of Martian and terrestrial dust devils

Abstract

[1] Recent experimental and modeling studies show that large quasi-static electric fields (2-20 kV/m) can be developed in a Martian or terrestrial dust devil as a result of contact electrification and charge separation of dust grains with different sizes and compositions. Electric discharging occurs when the maximum electric field reaches breakdown values ($20 kV/m on Mars and $3 MV/m on Earth, at surface altitudes). We derive a maximum electric field in a dust devil and develop a two-dimensional (2-D) cylindrically symmetric finite element model for Martian and terrestrial dust devil simulations. Unlike previous models with unlimited field growth, the tribocharging process and the time evolution of the dust devil electric field are self-consistently limited in our model and the saturated maximum electric fields in our simulations are comparable to past measurements. We study the saturated maximum electric fields for dust storms of different size, atmosphere conductivity and time rate of tribocharging. We also discuss the 2-D cylindrical field structures surrounding a dust devil and the conductivity gradient effect to the field growth of large Martian dust storms.

A model of the ULF magnetic and electric field generated from a dust devil

“…Note that there are two regions of current: One negative current moving upward near the eye of the dust devil (black region) associated with the upward lifting of small negative grains and a second positive current located along the outer region of the system (white region) associated with the more massive positive grains. As demonstrated previously [ Farrell et al , 2003; Zhai et al , 2006; Farrell et al , 2005], these currents give rise to a vertical electric field. Specifically, in the vertical direction, where J L is the current from the large positive grains, J S is the current from the small negative grains and σ E is the atmospheric dissipation current.…”

Electrical Activity and Dust Lifting on Earth, Mars, and Beyond

“…Melnik and Parrot (1998) were the first to numerically investigate the generation of E-fields in Martian dust storms and predicted that electric discharges are readily produced, although their charge transfer model was probably not realistic (see above). More recently, Renno et al (2004), Farrell et al (2004Farrell et al ( , 2006a, and Zhai et al (2006) developed simple models of the E-fields in terrestrial and Martian dust devils. These models also suggest the occurrence of electric discharges in Martian dusty phenomena.…”

“…Though appealing in its simplicity, this idea is problematic because it does not take into account pre-existing charges on the colliding particles and therefore poses no limit to the amount of charge transferred after many collisions. Moreover, the amount of charge transferred per collision is likely too large to be realistic (Zhai et al, 2006). Desch and Cuzzi (2000) developed a more sophisticated parameterization in which the charge transferred during each collision depends on the pre-existing charge, the particle radii, and the difference in contact potential between them.…”

“…Moreover, several studies suggest that E-fields generated in Martian dust storms can cause electric discharges (Eden and Vonnegut, 1973;Melnik and Parrot, 1998;Krauss et al, 2006;Farrell et al, 2003Farrell et al, , 2006aZhai et al, 2006;. The possible occurrence of large E-fields and the associated electric discharges has potentially important implications for Martian atmospheric chemistry, human exploration, habitability , Delory et al, 2006, and even the possible development of life (Miller, 1953).…”

Martian dust devil electron avalanche process and associated electrochemistry

“…It has been predicted through theoretical models that Martian dust devils may have large electrostatic fields, with their magnitudes approaching atmospheric breakdown levels of ∼25 kV/m [Melnik and Parrot, 1998;Farrell et al, 2003Farrell et al, , 2006bZhai et al, 2006]. These dust devil electric fields are formed through contact electrification, where larger sand and smaller dust grains collide with each other and the surface, generating and transferring electrical charge through friction [Ette, 1971;Melnik and Parrot, 1998;Desch and Cuzzi, 2000;Farrell et al, 2003].…”