Serbian Astronomical Journal 2016 Issue 192, Pages: 27-34
https://doi.org/10.2298/SAJ160220004M
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Orbit limited theory in the solar wind - κ distributions
Martinović M.M. (LESIA, Observatoire de Paris, Meudon, France + Faculty of Mathematics, Department of Astronomy, Belgrade + IHIS Techno-experts d.o.o. - Research and Development Center, Belgrade)
When a solid object is immersed into ionized gas it gets brought to a certain
value of electrostatic potential and surrounded by a space charge region
called ‘plasma sheath’. Through this region, particles are attracted or
repelled from the surface of the charge collecting object. For collisionless
plasma, this process is described by the so-called orbit limited theory,
which explains how the collection of particles is determined by the collector
geometry and plasma velocity distribution function (VDF). In this article, we
provide explicit expressions for orbit-limited currents for generalized
Lorentzian (κ) distributions. This work is useful to describe the charging
processes of objects in non-collisional plasmas like the solar wind, where
the electrons VDF is often observed to exhibit quasi power-law populations of
suprathermal particles. It is found that these ‘suprathermals’ considerably
increase the charge collection. Since the surface charging process that
determines the value of electrostatic potential is also affected by the
plasma VDF, calculation of the collector potential in the solar wind is
described along with some quantitative predictions. [Projekat Ministarstva
nauke Republike Srbije, br. 176002]
This article has been corrected. Link to the correction 10.2298/SAJ1795071E
Keywords: plasmas, Sun: solar wind