Effects of a kappa distribution function of electrons on incoherent scatter spectra

Saito, Susumu; Forme, F.; Buchert, Stephan; Nozawa, S.; Fujii, Ryosuke

doi:10.1007/s00585-000-1216-2

Cited by 46 publications

(26 citation statements)

References 10 publications

(12 reference statements)

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“…At high latitudes it has been shown that non-Maxwellian velocity distribution of electrons can increase the power of the ion-line spectra by 2-4 dB using the same parameters use for an assumed Maxwellian distribution (Saito et al, 2000;Bahcivan et al, 2006). However, it is very unlikely that these mechanisms will enhance the IS signal to the levels we are reporting.…”

Section: Discussionmentioning

confidence: 65%

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Naturally enhanced ion-line spectra around the equatorial 150-km region

et al. 2009

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Abstract. For many years strong radar echoes coming from 140-170 km altitudes at low latitudes have been associated to the existence of field-aligned irregularities (FAIs) (the so called 150-km echoes). In this work, we present frequency spectra as well as angular distribution of 150-km echoes. When the 150-km region is observed with beams perpendicular to the magnetic field (B) the observed radar spectra are very narrow with spectral widths between 3-12 m/s. On the other hand, when few-degrees off-perpendicular beams are used, the radar spectra are wide with spectral widths comparable to those expected from ion-acoustic waves at these altitudes (>1000 m/s). Moreover the off-perpendicular spectral width increases with increasing altitude. The strength of the received echoes is one to two orders of magnitude stronger than the expected level of waves in thermal equilibrium at these altitudes. Such enhancement is not due to an increase in electron density. Except for the enhancement in power, the spectra characteristics of off-perpendicular and perpendicular echoes are in reasonable agreement with expected incoherent scatter spectra at these angles and altitudes. 150-km echoes are usually observed in narrow layers (2 to 5). Bistatic common volume observations as well as observations made few kilometers apart show that, for most of the layers, there is very high correlation on power fluctuations without a noticeable time separation between simultaneous echoes observed with Off-perpendicular and Perpendicular beams. However, in one of the central layers, the echoes are the strongest in the perpendicular beam and absent or very weak in the offperpendicular beams, suggesting that they are generated by a plasma instability. Our results indicate that most echoes around 150-km region are not as aspect sensitive as originally thought, and they come from waves that have been enhanced above waves in thermal equilibrium.

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Section: Discussionmentioning

confidence: 65%

“…We can naively try to use 150-km offperpendicular spectra to diagnose this ionospheric region using the ISR technique, but without knowing the mechanism behind these echoes, the obtained parameters could be erroneous as reported at high latitudes when a wrong theory is fitted to the observations (e.g. Bahcivan et al, 2006;Saito et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Naturally enhanced ion-line spectra around the equatorial 150-km region

et al. 2009

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“…Decker and Krimigis 2003;Decker et al 2005;Heerikhuisen et al 2008Livadiotis et al 2011Livadiotis et al , 2013Livadiotis and McComas 2012a), and (3) other various plasma-related analyses (e.g. Milovanov and Zelenyi 2000;Saito et al 2000;Leubner 2004;Raadu and Shafiq 2007;Baluku et al 2010;Livadiotis and McComas 2009, 2010a, 2011bLe Roux et al 2010;Eslami et al 2011;Kourakis et al 2012; see also the work of Tribeche and collaborators in dusty plasmas, e.g., Tribeche et al 2009Tribeche and Bacha 2010;Tribeche and Merriche 2011;Roy et al 2012;Bains et al 2013). Because BG Statistical Mechanics cannot adequately describe non-equilibrium plasmas, new advances were required.…”

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confidence: 99%

Understanding Kappa Distributions: A Toolbox for Space Science and Astrophysics

2013

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In this paper we examine the physical foundations and theoretical development of the kappa distribution, which arises naturally from non-extensive Statistical Mechanics. The kappa distribution provides a straightforward replacement for the Maxwell distribution when dealing with systems in stationary states out of thermal equilibrium, commonly found in space and astrophysical plasmas. Prior studies have used a variety of inconsistent, and sometimes incorrect, formulations, which have led to significant confusion about these distributions. Therefore, in this study, we start from the N -particle phase space distribution and develop seven formulations for kappa distributions that range from the most general to several specialized versions that can be directly used with common types of space data. Collectively, these formulations and their guidelines provide a "toolbox" of useful and statistically well-grounded equations for future space physics analyses that seek to apply kappa distributions in data analysis, simulations, modeling, theory, and other work.

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“…The physical meaning of the Debye length 343 2001; Saito et al 2000;Leubner 2004;Raadu and Shafiq 2007;Hellberg et al 2009;Livadiotis and McComas 2009, 2010a-c, 2011a, 2011b, 2012, 2013aTribeche et al 2009;Le Roux et al 2010;Eslami et al 2011;Kourakis et al 2012;Yoon 2012;Yoon et al 2012;Bains et al 2013;Saberian and Esfandyari-Kalejahi 2013).…”

Section: And Zelenyi 2000mentioning

confidence: 99%

Electrostatic shielding in plasmas and the physical meaning of the Debye length

Livadiotis

McComas

2014

J. Plasma Phys.

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This paper examines the electrostatic shielding in plasmas, and resolves inconsistencies about what the Debye length really is. Two different interpretations of the Debye length are currently used: (1) The potential energy approximately equals the thermal energy, and (2) the ratio of the shielded to the unshielded potential drops to 1/e. We examine these two interpretations of the Debye length for equilibrium plasmas described by the Boltzmann distribution, and non-equilibrium plasmas (e.g. space plasmas) described by kappa distributions. We study three dimensionalities of the electrostatic potential: 1-D potential of linear symmetry for planar charge density, 2-D potential of cylindrical symmetry for linear charge density, and 3-D potential of spherical symmetry for a point charge. We resolve critical inconsistencies of the two interpretations, including: independence of the Debye length on the dimensionality; requirement for small charge perturbations that is equivalent to weakly coupled plasmas; correlations between ions and electrons; existence of temperature for nonequilibrium plasmas; and isotropic Debye shielding. We introduce a third Debye length interpretation that naturally emerges from the second statistical moment of the particle position distribution; this is analogous to the kinetic definition of temperature, which is the second statistical moment of the velocity distribution. Finally, we compare the three interpretations, identifying what information is required for theoretical/experimental plasma-physics research: Interpretation 1 applies only to kappa distributions; Interpretation 2 is not restricted to any specific form of the ion/electron distributions, but these forms have to be known; Interpretation 3 needs only the second statistical moment of the positional distribution.

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Effects of a kappa distribution function of electrons on incoherent scatter spectra

Cited by 46 publications

References 10 publications

Naturally enhanced ion-line spectra around the equatorial 150-km region

Naturally enhanced ion-line spectra around the equatorial 150-km region

Understanding Kappa Distributions: A Toolbox for Space Science and Astrophysics

Electrostatic shielding in plasmas and the physical meaning of the Debye length

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