Nanodust shedding and its potential influence on dust‐related phenomena in the mesosphere

Havnes, O.; Hartquist, T. W.

doi:10.1002/2016jd025037

Cited by 3 publications

(3 citation statements)

References 67 publications

(137 reference statements)

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“…For a typical rocket speed of 800-1000 m s −1 , the fragmentation model and single projectile have roughly the same yield. We find that the predicted charge number for this velocity range is consistent with what has been measured with rocketborne Faraday cups (Havnes and Naesheim, 2007;Havnes et al, 2014). The grey shaded area shows values of the predicted charge yield where the ice particles have a capacitive coupling but are allowed to have a non-unity dielectric constant (cf.…”

Section: Ice-metal Collisionssupporting

confidence: 84%

A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

et al. 2021

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Abstract. We investigate the generation of charge due to collision between projectiles with sizes below ∼1 µm and metal surfaces at speeds ∼0.1 to 10 km s−1. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. Impact charge production at these low to intermediate speeds has traditionally been described by invoking the theory of shock wave ionization. By looking at the thermodynamics of the low-velocity solution of shock wave ionization, we find that such a mechanism alone is not sufficient to account for the recorded charge production in a number of scenarios in the laboratory and in space. We propose a model of capacitive contact charging that involves no direct ionization, in which we allow for projectile fragmentation upon impact. Furthermore, we show that this model describes measurements of metal–metal impacts in the laboratory well. We also address contact charging in the context of ice-on-metal collisions and apply our results to rocket observations of mesospheric dust. In general, we find that contact charging dominates at speeds of up to a few kilometres per second and complements shock wave ionization up to speeds where direct ionization can take place. The conditions that we consider can be applied to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta.

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Section: Ice-metal Collisionssupporting

confidence: 84%

A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

et al. 2021

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“…As a third explanation, we must mention a recent development in charging mechanisms for mesospheric nanoparticles that may explain a possible physical mechanism, where larger MSPs can be more abundant in the fragment distribution at the top of a NLC/PMSE layer. In a recent work, Havnes and Hartquist () proposed a new mechanism where MSPs can scavenge electrons from larger ice particles (so called “nanodust shedding”) that can further affect the internal distribution of MSP sizes inside ice particles. The physical explanation is that the switching time of the polarized (“image”) potential on the surface of an ice particles is slow compared to the charging and escape rate of an impinging MSP.…”

Section: Derived Size Distributions Of Collision Fragmentsmentioning

confidence: 99%

Estimates of the Size Distribution of Meteoric Smoke Particles From Rocket‐Borne Impact Probes

2017

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Ice particles populating noctilucent clouds and being responsible for polar mesospheric summer echoes exist around the mesopause in the altitude range from 80 to 90 km during polar summer. The particles are observed when temperatures around the mesopause reach a minimum, and it is presumed that they consist of water ice with inclusions of smaller mesospheric smoke particles (MSPs). This work provides estimates of the mean size distribution of MSPs through analysis of collision fragments of the ice particles populating the mesospheric dust layers. We have analyzed data from two triplets of mechanically identical rocket probes, MUltiple Dust Detector (MUDD), which are Faraday bucket detectors with impact grids that partly fragments incoming ice particles. The MUDD probes were launched from Andøya Space Center (69°17'N, 16°1'E) on two payloads during the MAXIDUSTY campaign on 30 June and 8 July 2016, respectively. Our analysis shows that it is unlikely that ice particles produce significant current to the detector, and that MSPs dominate the recorded current. The size distributions obtained from these currents, which reflect the MSP sizes, are described by inverse power laws with exponents of k∼ [3.3 ± 0.7, 3.7 ± 0.5] and k∼ [3.6 ± 0.8, 4.4 ± 0.3] for the respective flights. We derived two k values for each flight depending on whether the charging probability is proportional to area or volume of fragments. We also confirm that MSPs are probably abundant inside mesospheric ice particles larger than a few nanometers, and the volume filling factor can be a few percent for reasonable assumptions of particle properties.

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“…As shown in our results below, h ∼ 0.1r p offers a good fit for rocket data. Note that we have disregarded polarization effects, as the characteristic polarization potential switching times for particles of sizes used here, are likely much longer than the collision time (or contact time) (Havnes and Hartquist, 2016). We employ the same parameterization of fragment size distribution in both the fragmentation-at-impact model (iron particles) and fragments-in-projectile model (ice particles containing meteoric smoke particles -MSPs), namely:…”

Section: Fragmentation Modelmentioning

confidence: 99%

A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space

Antonsen¹,

Mann²,

Vaverka³

et al. 2020

Preprint

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Abstract. We investigate the generation of charge during collision of projectiles with sizes below ~ 1 μm and metal surfaces at speeds ~ 0.1 km/s. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. The conditions that we consider apply to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta. We introduce a model of capacitive contact charging in which we allow for projectile fragmentation upon impact, and show that this model describes measurements of metal-metal impacts in the laboratory and in-situ measurements of dust in the Earth's atmosphere well. We have considered the utilization of our model for different scenarios in interplanetary space and in Earth's atmosphere. From this discussion we find it likely that our work can be employed in a number of situations where impact velocities are relatively small. Furthermore, we have discussed the thermodynamics of the low velocity solution of shock wave ionization, and conclude that the impurity charging effect utilized in the much used model of Drapatz and Michel (1974) does not sufficiently describe charge generation at impact speeds below a few kilometers per second. Consequently, impact charging at low speeds cannot be described with a Saha-solution.

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Nanodust shedding and its potential influence on dust‐related phenomena in the mesosphere

Cited by 3 publications

References 67 publications

A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

Estimates of the Size Distribution of Meteoric Smoke Particles From Rocket‐Borne Impact Probes

A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space

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