Solar Wind Thermally Induced Magnetic Fluctuations

Navarro, R.; Moya, P. S.; Muñoz, Vı́ctor; Araneda, J. A.; Viñas, A. F.; Valdivia, J. A.

doi:10.1103/physrevlett.112.245001

Cited by 32 publications

(43 citation statements)

References 29 publications

(49 reference statements)

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“…This feature agrees with previous results. [18][19][20] Because of the condition K À ¼ 0 [see Eqs. (32)-(35)], the electromagnetic fluctuation level exhibits intense peaks near the modes with ImðxÞ $ 0.…”

Section: Numerical Results For a Core-beam Proton Plasmamentioning

confidence: 99%

“…6 ¼ 0 should also provide a significant contribution since the random motion of particles should also produce fluctuations that propagate obliquely with respect to the background magnetic field. Thus, this and earlier studies [18][19][20] should be regarded as a first step towards a more general analysis including nonparallel propagating fluctuations, which will be considered in a follow-up paper.…”

Section: Discussionmentioning

confidence: 96%

“…4,[18][19][20] The parallel propagating thermally induced magnetic fluctuations seem to be a relevant contribution to the solar wind plasma under conditions stable to anisotropydriven instabilities. 20 However, we expect that fluctuations with k ? 6 ¼ 0 should also provide a significant contribution since the random motion of particles should also produce fluctuations that propagate obliquely with respect to the background magnetic field.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, fluctuations may be due to remnant MHD turbulent magnetic fluctuations advected from the Sun, which may be relevant if the time expansion of the MHD turbulence is much shorter than the fluctuation time scales. In this paper, we take the approach of considering the contribution of thermal fluctuations, which are known to arise naturally in most statistical systems, and particularly in quasi-equilibrium plasmas, without imposing initially unstable growing waves 17,20 or preexistent turbulence. a) Electronic mail: roberto.navarro@ug.uchile.cl…”

Section: Introductionmentioning

confidence: 99%

“…was studied by Navarro et al20 for anisotropic Maxwellian proton plasmas. For isotropic plasmas, Eqs.…”

mentioning

confidence: 99%

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Theory of electromagnetic fluctuations for magnetized multi-species plasmas

et al. 2014

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Dynamics of the dissipation range for solar wind magnetic fluctuations AIP Conf.Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians. V C 2014 AIP Publishing LLC. [http://dx.

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Section: Numerical Results For a Core-beam Proton Plasmamentioning

confidence: 99%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…was studied by Navarro et al20 for anisotropic Maxwellian proton plasmas. For isotropic plasmas, Eqs.…”

mentioning

confidence: 99%

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Theory of electromagnetic fluctuations for magnetized multi-species plasmas

et al. 2014

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Magnetic Alfvén‐cyclotron fluctuations of anisotropic nonthermal plasmas

et al. 2015

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Remote and in situ observations in the solar wind show that ion and electron velocity distributions persistently present deviations from thermal equilibrium. Ion anisotropies seem to be constrained by instability thresholds which are in agreement with linear kinetic theory. For plasma states below these instability thresholds, the quasi-stable solar wind plasma sustains a small but detectable level of magnetic fluctuation power. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness and thermal motion of charged particles. Here we study magnetic Alfvén-cyclotron fluctuations propagating along a background magnetic field in a plasma composed of thermal and suprathermal protons and electrons via the fluctuation-dissipation theorem. The total fluctuating magnetic power is estimated in a proton temperature anisotropy-beta diagram for three different families of proton distribution functions, which can be compared to a number of recent measurements in the solar wind.

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Electromagnetic fluctuations of the whistler‐cyclotron and firehose instabilities in a Maxwellian and Tsallis‐kappa‐like plasma

et al. 2015

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Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of nonthermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field-aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of the electron whistler-cyclotron and firehose fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis-kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and nonthermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and nonthermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of nonthermal distributions due to the effective higher temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and nonthermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in situ particle measurements.

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Solar Wind Thermally Induced Magnetic Fluctuations

Cited by 32 publications

References 29 publications

Theory of electromagnetic fluctuations for magnetized multi-species plasmas

Theory of electromagnetic fluctuations for magnetized multi-species plasmas

Magnetic Alfvén‐cyclotron fluctuations of anisotropic nonthermal plasmas

Electromagnetic fluctuations of the whistler‐cyclotron and firehose instabilities in a Maxwellian and Tsallis‐kappa‐like plasma

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