Revisiting the role of magnetic moments in heliospheric plasmas

Fahr, H. J.; Siewert, M.

doi:10.1051/0004-6361/201220965

Cited by 6 publications

(4 citation statements)

References 44 publications

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“…The term T1, describing magnetic cooling due to the conservation of the particle's magnetic moment (see Fahr & Siewert 2013), has the following detailed representation:…”

Section: Study Of the Distribution Function Along Heliosheath Flow Linesmentioning

confidence: 99%

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Concerning pressure and entropy of shock-accelerated heliosheath electrons

Fahr

Dutta-Roy

2019

Monthly Notices of the Royal Astronomical Society

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We study the behaviour of shocked wind-electrons leaving wind-driving stars after undergoing the outer wind termination shock. As an example, we describe the evolution of the keV-energetic electron distribution function downstream of the heliospheric termination shock. We start from a kinetic transport equation in the bulk frame of the heliosheath plasma flow taking into account shock-induced electron injection, convective changes, cooling processes, and whistler wave-induced energy diffusion. From this equation we proceed to an associated pressure moment of the electron distribution function arriving at a corresponding pressure transport equation which describes the evolution of the electron pressure in the bulk frame of the plasma along the plasma flow lines. We assume that the local distribution function, in view of the prevailing non-LTE conditions, is represented by a local kappa function with local kappa parameters that vary with the streamline coordinate s downstream of the solar wind termination shock. We obtain the solution for the electron pressure as a function of the streamline coordinate s from the pressure transport equation and demonstrate that, connected with this pressure, one obtains an expression for the entropy of the electron fluid which can also be derived as a streamline function. We show that the heliosheath electron fluid can essentially be characterized as an isobaric and isentropic flow. These results allow to generally conclude that astrotail plasma flows are characterized as such flows.

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“…The term T1, describing magnetic cooling due to the conservation of the particle's magnetic moment (see Fahr & Siewert 2013), has the following detailed representation:…”

Section: Study Of the Distribution Function Along Heliosheath Flow Linesmentioning

confidence: 99%

“…where the magnetic velocity drift v m due to magnetic moment conservation is given by (see Fahr 2007;Fahr & Fichtner 2011;Fahr & Siewert 2013)…”

Section: Study Of the Distribution Function Along Heliosheath Flow Linesmentioning

confidence: 99%

Concerning pressure and entropy of shock-accelerated heliosheath electrons

Fahr

Dutta-Roy

2019

Monthly Notices of the Royal Astronomical Society

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“…A further hint is also given by Fahr and Siewert (2013) who show that the Liouville operator in conventional ion transport equations just takes care that particle energy and magnetic moment are conserved at free ion motions, while simultaneously operating typical Fokker-Planck diffusion terms, e.g. for pitch-angle scattering, can be additionally considered as counteracting the magnetic moment conservation.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

On the electron temperature downstream of the solar wind termination shock

Чашей

Fahr

2013

Ann. Geophys.

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In this paper we study the temperatures of electrons convected with the solar wind to large solar distances and finally transported over the solar wind termination shock. Nearly nothing, unless at high energies in the cosmic ray regime, is known about the thermodynamical behaviour of these distant electrons from in~situ plasma observations. Hence it is tacitly assumed these electrons, due to their adiabatic behaviour and vanishing heat conduction or energization processes, have rapidly cooled off to very low temperatures once they eventually arrive at the solar wind termination shock (at about 100 AU). In this paper we show that such electrons, however, at their passage over the termination shock due to the shock–electric field action undergo an over-adiabatic heating and therefore appear on the downstream side as a substantially heated plasma species. Looking quantitatively into this heating process we find that solar wind electrons achieve temperatures of the order of 2–4 × 10⁶ K downstream of the termination shock, depending on the upstream solar wind bulk velocity and the shock compression ratio. Hence these electrons therewith play an important dynamical role in structuring this shock and determining the downstream plasma flow properties. Furthermore, they present an additional ionization source for incoming neutral interstellar hydrogen and excite X-ray emission. They also behave similar to cosmic ray electrons and extend to some limited region upstream of the shock of the order of 0.1 AU by spatial diffusion and thereby also modify the upstream solar wind properties

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“…thermischen Protonen, besitzen hier Temperaturen von einigen Millionen Grad Kelvin [1]. Die schwereren Ionen von Helium, Sauerstoff und Stickstoff befinden sich aufgrund der hohen Temperaturen alle in hohen elektrischen Ladungszuständen.…”

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Voyager 1 ist im interstellaren Raum

Fahr¹

2014

Physik in unserer Zeit

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Revisiting the role of magnetic moments in heliospheric plasmas

Cited by 6 publications

References 44 publications

Concerning pressure and entropy of shock-accelerated heliosheath electrons

Concerning pressure and entropy of shock-accelerated heliosheath electrons

On the electron temperature downstream of the solar wind termination shock

Voyager 1 ist im interstellaren Raum

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