Current–voltage relationship

Pierrard, Viviane; Khazanov, G. V.; Lemaire, J.

doi:10.1016/j.jastp.2007.08.005

Cited by 17 publications

(12 citation statements)

References 30 publications

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“…Fridman and Lemaire (1980) found that for parameters of interest in the upward current region the current is proportional to the potential drop. Similar current-voltage characteristics were later found for plasmas with kappa distributions (Pierrard, 1996;Pierrard et al, 2007).…”

Section: Introductionsupporting

confidence: 79%

Vlasov simulations of parallel potential drops

et al. 2013

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An auroral flux tube is modelled from the magnetospheric equator to the ionosphere using Vlasov simulations. Starting from an initial state, the evolution of the plasma on the flux tube is followed in time. It is found that when applying a voltage between the ends of the flux tube, about two thirds of the potential drop is concentrated in a thin double layer at approximately one Earth radius altitude. The remaining part is situated in an extended region 1–2 Earth radii above the double layer. Waves on the ion timescale develop above the double layer, and they move toward higher altitude at approximately the ion acoustic speed. These waves are seen both in the electric field and as perturbations of the ion and electron distributions, indicative of an instability. Electrons of magnetospheric origin become trapped between the magnetic mirror and the double layer during its formation. At low altitude, waves on electron timescales appear and are seen to be non-uniformly distributed in space. The temporal evolution of the potential profile and the total voltage affect the double layer altitude, which decreases with an increasing field aligned potential drop. A current–voltage relationship is found by running several simulations with different voltages over the system, and it agrees with the Knight relation reasonably well

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Section: Introductionsupporting

confidence: 79%

Vlasov simulations of parallel potential drops

et al. 2013

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“…Pierrard (1996) and Pierrard, Khazanov, and Lemaire (2007) obtained new current -voltage relationships in auroral regions when suprathermal particles were assumed to be present with Lorentzian and bi-Lorentzian distributions. Field-aligned conductance values were also estimated from Maxwellian and Kappa distributions in quiet and disturbed events using Freja electron data (Olsson and Janhunen, 1998).…”

Section: Earth's Exospherementioning

confidence: 99%

Kappa Distributions: Theory and Applications in Space Plasmas

Pierrard¹,

Lazar²

2010

Sol Phys

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425

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The plasma particle velocity distributions observed in the solar wind generally show enhanced (non-Maxwellian) suprathermal tails, decreasing as a power law of the velocity and well described by the family of Kappa distribution functions. The presence of non-thermal populations at different altitudes in space plasmas suggests a universal mechanism for their creation and important consequences concerning plasma fluctuations, the resonant and nonresonant wave -particle acceleration and plasma heating. These effects are well described by the kinetic approaches where no closure requires the distributions to be nearly Maxwellian. This paper summarizes and analyzes the various theories proposed for the Kappa distributions and their valuable applications in coronal and space plasmas.

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“…It has been computed by several authors for a monotonically decreasing with altitude and assuming adiabatic motion of particles along the flux tube connecting the ionospheric load and the magnetospheric generator described by Maxwellian (Knight, 1973;Lemaire and Scherer, 1973;Chiu and Schulz, 1978), biMaxwellian (Fridman and Lemaire, 1980) or kappa (Pierrard, 1996) velocity distribution functions. A recent review on the currentvoltage relation has been published by Pierrard et al (2007). The current-voltage relation can be linearized for a limited range of (Knight, 1973;Lyons et al, 1979).…”

Section: A Quasi-stationary Model For the Coupling Betweenmentioning

confidence: 99%

Ionospheric feedback effects on the quasi-stationary coupling between LLBL and postnoon/evening discrete auroral arcs

2008

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Abstract. We discuss a model for the quasi-stationary coupling between magnetospheric sheared flows in the dusk sector and discrete auroral arcs, previously analyzed for the case of a uniform height-integrated Pedersen conductivity ( P ). Here we introduce an ionospheric feedback as the variation of P with the energy flux of precipitating magnetospheric electrons ( em ). One key-component of the model is the kinetic description of the interface between the duskward LLBL and the plasma sheet that gives the profile of m , the magnetospheric electrostatic potential. The velocity shear in the dusk LLBL plays the role of a generator for the auroral circuit closing through Pedersen currents in the auroral ionosphere. The field-aligned current density, j || , and the energy flux of precipitating electrons are given by analytic functions of the field-aligned potential drop, , derived from standard kinetic models of the adiabatic motion of particles. The ionospheric electrostatic potential, i (and implicitely ) is determined from the current continuity equation in the ionosphere. We obtain values of of the order of kilovolt and of j || of the order of tens of µA/m 2 in thin regions of the order of several kilometers at 200 km altitude. The spatial scale is significantly smaller and the peak values of , j || and em are higher than in the case of a uniform P . Effects on the postnoon/evening auroral arc electrodynamics due to variations of dusk LLBL and solar wind dynamic and kinetic pressure are discussed. In thin regions (of the order of kilometer) embedding the maximum of we evidence a non-linear regime of the current-voltage relationship. The model predicts also that visible arcs form when the velocity shear in LLBL is above a threshold value depending on the generator and ionospheric plasma properties. Brighter arcs are obtained for increased velocity shear in the LLBL; their spatial scale remains virtually unmodified. The field-aligned potential drop tends to decrease with increasing LLBL denCorrespondence to: M. M. Echim (marius.echim@oma.be) sity. For higher values of the LLBL electron temperature the model gives negative field-aligned potential drops in regions adjacent to upward field-aligned currents.

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Current–voltage relationship

Cited by 17 publications

References 30 publications

Vlasov simulations of parallel potential drops

Vlasov simulations of parallel potential drops

Kappa Distributions: Theory and Applications in Space Plasmas

Ionospheric feedback effects on the quasi-stationary coupling between LLBL and postnoon/evening discrete auroral arcs

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