Abstract
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.
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geology,Astronomy and Astrophysics
Reference59 articles.
1. Adams, N. and Smith, D.: Studies of microparticle impact phenomena leading to
the development of a highly sensitive micrometeoroid detector, Planet.
Space Sci., 19, 195–204, https://doi.org/10.1016/0032-0633(71)90199-1, 1971. a
2. Antonsen, T.: In-situ Measurements of Mesospheric Aerosols – On the observable
characteristics of nanoscale ice and meteoric smoke particles, Ph.D. thesis,
UiT The Arctic University of Norway, Tromsø, 2019. a, b
3. Antonsen, T. and Havnes, O.: On the detection of mesospheric meteoric smoke
particles embedded in noctilucent cloud particles with rocket-borne dust
probes, Rev. Sci. Instrum., 86, 033305,
https://doi.org/10.1063/1.4914394, 2015. a, b
4. Antonsen, T., Havnes, O., and Mann, I.: Estimates of the Size Distribution of
Meteoric Smoke Particles From Rocket-Borne Impact Probes, J.
Geophys. Res.-Atmos., 122, 12353–12365, https://doi.org/10.1002/2017JD027220, 2017. a, b, c
5. Antonsen, T., Havnes, O., and Spicher, A.: Replication Data for: Multi-scale Measurements of Mesospheric Aerosols and Electrons During the MAXIDUSTY campaign, DataverseNO [Dataset], https://doi.org/10.18710/N8GF1U (last access: 11 June 2021), 2018. a