Quasilinear evolution of plasma distribution functions and consequences on wave spectrum and perpendicular ion heating in the turbulent solar wind

Abstract Instabilities described by linear theory characterize an important form of wave–particle interaction in the solar wind. We diagnose unstable behavior of solar wind plasma between 0.3 and 1 au via the Nyquist criterion, applying it to fits of ∼1.5M proton and α particle Velocity Distribution Functions (VDFs) observed by Helios I and II. The variation of the fraction of unstable intervals with radial distance from the Sun is linear, signaling a gradual decline in the activity of unstable modes. When calculated as functions of the solar wind velocity and Coulomb number, we obtain more extreme, exponential trends in the regions where collisions appear to have a notable influence on the VDF. Instability growth rates demonstrate similar behavior, and significantly decrease with Coulomb number. We find that for a nonnegligible fraction of observations, the proton beam or secondary component might not be detected, due to instrument resolution limitations, and demonstrate that the impact of this issue does not affect the main conclusions of this work.

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Impact of non-thermal electrons on spatial damping: a kinetic model for the parallel propagating modes

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0352 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Muhammad Sarfraz ◽

Gohar Abbas ◽

Hashim Farooq ◽

I. Zeba

Keyword(s):

Kinetic Model ◽

Wave Spectrum ◽

Field Approximation ◽

Weak Field ◽

Distribution Functions ◽

Global Perspective ◽

Energetic Electrons ◽

Thermal Anisotropy ◽

Spatial Damping

Abstract A sequence of in situ measurements points the presence of non-thermal species in the profile of particle distributions. This study highlights the role of such energetic electrons on the wave-spectrum. Using Vlasov–Maxwell’s model, the dispersion relations of the parallel propagating modes along with the space scale of damping are discussed using non-relativistic bi-Maxwellian and bi-Kappa distribution functions under the weak field approximation, i.e., ω − k . v > Ω 0 $\left\vert \omega -\mathbf{k}.\mathbf{v}\right\vert { >}{{\Omega}}_{0}$ . Power series and asymptotic expansions of plasma dispersion functions are performed to derive the modes and spatial damping of waves, respectively. The role of these highly energetic electrons is illustrated on real frequency and anomalous damping of R and L-modes which is in fact controlled by the parameter κ in the dispersion. Further, we uncovered the effect of external magnetic field and thermal anisotropy on such spatial attenuation. In global perspective of the kinetic model, it may be another step.

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Analysis of Alfvénic flows with Solar Orbiter: particle and magnetic observations down to kinetic scales.

10.5194/egusphere-egu21-10238 ◽

2021 ◽

Author(s):

Philippe Louarn ◽

Andrei fedorov ◽

alexis Rouillard ◽

Benoit Lavraud ◽

Vincent Génot ◽

...

Keyword(s):

Solar Wind ◽

Fine Structure ◽

Time Resolution ◽

Time Scale ◽

Residual Energy ◽

Distribution Functions ◽

Strongly Correlated ◽

Temperature Anisotropy ◽

Velocity Fluctuations ◽

Turbulence Parameters

<p>The magnetic and velocity fluctuations of the solar wind may be strongly correlated. This characterizes the&#160; &#8216;Alfvenic&#8217; flows. Using the observations of the Proton Alfa sensor (PAS/SWA) and the magnetometer (MAG) onboard Solar Orbiter, we analyze a period of 100 hours of such alfvenic flows, at different scales. Several parameters of the turbulence are computed (V-B correlation, various spectral indexes, cross-helicity, residual energy). We explore how these parameters may vary with time and characterize different turbulent states of the flow. More specifically, using the unprecedented time resolution of PAS during burst mode, especially its capability to measure 3D distribution functions at time scale below the proton gyroperiod, we study the connection of the turbulence to the dissipation domain and analyze the fine structure of the distribution functions and their evolutions at sub-second scales. The goal is to investigate whether some characteristics of the distributions, as their more or less pronounced temperature anisotropy, may be related to the turbulence parameters and the degree of V-B correlation.</p>

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A Global Survey of Geospace Electrons with eVlasiator: First Results

10.5194/egusphere-egu21-10638 ◽

2021 ◽

Author(s):

Markku Alho ◽

Markus Battarbee ◽

Yann Pfau-Kempf ◽

Urs Ganse ◽

Lucile Turc ◽

...

Keyword(s):

Solar Wind ◽

Spatial Resolution ◽

Kinetic Models ◽

Electron Distribution ◽

State Of The Art ◽

Distribution Functions ◽

Upper Atmosphere ◽

Electron Precipitation ◽

Gas Dynamic ◽

First Results

<div> <p>Models of the&#160;geospace&#160;plasma environment have been proceeding towards more realistic descriptions of the solar wind&#8212;magnetosphere interaction, from gas-dynamic to MHD and hybrid ion-kinetic models such as the state-of-the-art&#160;Vlasiator&#160;model.&#160;Advances in computational capabilities have enabled global&#160;simulations of detailed physics, but the electron scale has so far been out of reach in a truly global setting.&#160;</p> </div><div> <p>In this work we present results from eVlasiator, an offshoot of the Vlasiator model, showing first results from a global 2D+3V kinetic electron geospace simulation. Despite truncation of some electron physics and use of ion-scale spatial resolution, we show that realistic electron distribution functions are obtainable within the magnetosphere and describe these in relation to MMS observations. Electron precipitation to the upper atmosphere from these velocity distributions is estimated.</p> </div>

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Ion energy and momentum flux near the cometopause of Comet 67P/Churyumov-Gerasimenko

10.5194/egusphere-egu21-14280 ◽

2021 ◽

Author(s):

Hayley Williamson ◽

Hans Nilsson ◽

Anja Moslinger ◽

Sofia Bergman ◽

Gabriella Stenberg-Wieser

Keyword(s):

Solar Wind ◽

Complex Dynamics ◽

Distribution Functions ◽

Transitional Period ◽

Ion Energy ◽

Rosetta Mission ◽

Before And After ◽

Composition Analyzer ◽

Energy And Momentum ◽

Comet 67P

<p>Defined as the region where the plasma interaction region of a comet goes from being solar wind-dominated to cometary ion-dominated, the cometopause is a region of comingling plasmas and complex dynamics. The Rosetta mission orbited comet 67P/Churyumov-Gerasimenko for roughly two years. During this time, the cometopause was observed by the Ion Composition Analyzer (ICA), part of the Rosetta Plasma Consortium (RPC), before and after the spacecraft was in the solar wind ion cavity, defined as the region where no solar wind ions were measured. Data from ICA shows that solar wind and cometary ions have similar momentum and energy flux moments during this transitional period, indicating mass loading and deflection of the solar wind. We examine higher order moments and distribution functions for the solar wind and cometary species between December 2015 and March 2016. The behavior of the solar wind protons indicates that in many cases these protons are deflected in a sunward direction, while the cometary ions continue to move predominately antisunward. By studying the distribution functions of the protons during these time periods, it is possible to see a non-Maxwellian energy distribution. This can inform on the nature of the cometopause boundary and the energy transfer mechanisms at play in this region.</p>

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Perpendicular Ion Heating by Cyclotron Resonant Dissipation of Turbulently Generated Kinetic Alfvén Waves in the Solar Wind

The Astrophysical Journal ◽

10.3847/1538-4357/ab4e12 ◽

2019 ◽

Vol 887 (1) ◽

pp. 63 ◽

Cited By ~ 6

Author(s):

Philip A. Isenberg ◽

Bernard J. Vasquez

Keyword(s):

Solar Wind ◽

Alfven Waves ◽

Alfvén Waves ◽

Ion Heating ◽

Kinetic Alfvén Waves

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An instrument for rapidly measuring plasma distribution functions with high resolution

Advances in Space Research ◽

10.1016/0273-1177(82)90151-x ◽

1982 ◽

Vol 2 (7) ◽

pp. 67-70 ◽

Cited By ~ 143

Author(s):

C.W. Carlson ◽

D.W. Curtis ◽

G. Paschmann ◽

W. Michel

Keyword(s):

High Resolution ◽

Distribution Functions ◽

Plasma Distribution

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Closure of multi-fluid and kinetic equations for cyclotron-resonant interactions of solar wind ions with Alfvén waves

Nonlinear Processes in Geophysics ◽

10.5194/npg-5-111-1998 ◽

1998 ◽

Vol 5 (2) ◽

pp. 111-120 ◽

Cited By ~ 27

Author(s):

E. Marsch

Keyword(s):

Velocity Component ◽

Ion Beam ◽

Wave Spectrum ◽

Particle Interaction ◽

Kinetic Equations ◽

Distribution Functions ◽

Average Intensity ◽

Temperature Anisotropy ◽

Quasilinear Theory ◽

Resonant Interactions

Abstract. Based on quasilinear theory, a closure scheme for anisotropic multi-component fluid equations is developed for the wave-particle interactions of ions with electromagnetic Alfvén and ion-cyclotron waves propagating along the mean magnetic field. Acceleration and heating rates are calculated. They may be used in the multi-fluid momentum and energy equations as anomalous transport terms. The corresponding evolution equation for the average wave spectrum is established, and the effective growth/damping rate for the spectrum is calculated. Given a simple power-law spectrum, an anomalous collision frequency can be derived which depends on the slope and average intensity of the spectrum, and on the gyrofrequency and the differential motion (with respect to the wave frame) of the actual ion species considered. The wave-particle interaction terms attain simple forms resembling the ones for collisional friction and temperature anisotropy relaxation (due to pitch angle scattering) with collision rates that are proportional to the gyrofrequency but diminished substantially by the relative wave energy or the fluctuation level with respect the background field. In addition, a set of quasilinear diffusion equations is derived for the reduced (with respect to the perpendicular velocity component) velocity distribution functions (VDFs), as they occur in the wave dispersion equation and the related dielectric function for parallel propagation. These reduced VDFs allow one to describe adequately the most prominent observed features, such as an ion beam and temperature anisotropy, in association with the resonant interactions of the particles with the waves on a kinetic level, yet have the advantage of being only dependent upon the parallel velocity component.

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Solar wind and kinetic heliophysics

Annales Geophysicae ◽

10.5194/angeo-36-1607-2018 ◽

2018 ◽

Vol 36 (6) ◽

pp. 1607-1630 ◽

Cited By ~ 5

Author(s):

Eckart Marsch

Keyword(s):

Solar Wind ◽

Interplanetary Space ◽

Coronal Holes ◽

Heavy Ion ◽

Alfven Waves ◽

Distribution Functions ◽

Slow Solar Wind ◽

Alfvén Waves ◽

The Sun ◽

Collisionless Dissipation

Abstract. This paper reviews recent aspects of solar wind physics and elucidates the role Alfvén waves play in solar wind acceleration and turbulence, which prevail in the low corona and inner heliosphere. Our understanding of the solar wind has made considerable progress based on remote sensing, in situ measurements, kinetic simulation and fluid modeling. Further insights are expected from such missions as the Parker Solar Probe and Solar Orbiter. The sources of the solar wind have been identified in the chromospheric network, transition region and corona of the Sun. Alfvén waves excited by reconnection in the network contribute to the driving of turbulence and plasma flows in funnels and coronal holes. The dynamic solar magnetic field causes solar wind variations over the solar cycle. Fast and slow solar wind streams, as well as transient coronal mass ejections, are generated by the Sun's magnetic activity. Magnetohydrodynamic turbulence originates at the Sun and evolves into interplanetary space. The major Alfvén waves and minor magnetosonic waves, with an admixture of pressure-balanced structures at various scales, constitute heliophysical turbulence. Its spectra evolve radially and develop anisotropies. Numerical simulations of turbulence spectra have reproduced key observational features. Collisionless dissipation of fluctuations remains a subject of intense research. Detailed measurements of particle velocity distributions have revealed non-Maxwellian electrons, strongly anisotropic protons and heavy ion beams. Besides macroscopic forces in the heliosphere, local wave–particle interactions shape the distribution functions. They can be described by the Boltzmann–Vlasov equation including collisions and waves. Kinetic simulations permit us to better understand the combined evolution of particles and waves in the heliosphere.

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