The influence of multiple ion species on Alfvén wave dispersion and Alfvén wave plasma heating

<p>Appearance of measurements of the interplanetary medium parameters with high temporal resolution gave rise to a variety of investigations of turbulent cascade at ion kinetic scales at which processes of plasma heating was believed to operate. Our recent studies based on high frequency plasma measurements at Spektr-R spacecraft have shown that the turbulent cascade was not stable and dynamically changed depending on the plasma conditions in different large-scale solar wind structures. These changes was most significant at the kinetic scales of the turbulent cascade. Slow undisturbed solar wind was characterized by the consistency of the spectra to the predictions of the kinetic Alfven wave turbulence model. On the other hand, the discrepancy between the model predictions and registered spectra were found in stream interaction regions characterized by crucial steepening of spectra at the kinetic scales with slopes having values up to -(4-5). This discrepancy was clearly shown for plasma compression region Sheath in front of the magnetic clouds and CIR in front of high speed streams associated with coronal holes. Present study is focused on the break preceding the kinetic scales. Currently the characteristic plasma parameters associated with the formation of the break is still debated. Number of studies demonstrated that the break was consistent with distinct characteristic frequencies for different values &#8203;&#8203;of the plasma proton parameter beta &#946;p. Present study consider the ratio between the break frequency determined for ion flux fluctuation spectra according to Spektr-R data and several characteristic plasma frequencies used traditionally in such cases. The value of this ratio is statistically compared for different large-scale solar wind streams. We analyze both the classical spectrum view with two slopes and one break and the spectrum with flattening between magnetohydrodynamic and kinetic scales.&#160; Our results show that for the Sheath and CIR regions characterized typically by &#946;p &#8804;1 the break corresponds statistically to the frequency determined by the proton gyroradius. At the same time such correspondence are not observed either for the undisturbed slow solar wind with similar &#946;p value or for disturbed flows associated with interplanetary manifestations of coronal mass ejections, where &#946;p << 1. The results also shows that in slow undisturbed solar wind the break is closer to the frequency determined by the inertial proton length. Thus, apparently the transition between streams of different speeds may result in the change of dissipation regimes and plays role in plasma heating at these areas. This work was supported by the RFBR grant No. 19-02-00177a</p>

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Concerning the Dynamics of Energetic Protons in Coronal Magnetic Loops: Dispersion Effects of Alfven Waves

Symposium - International Astronomical Union ◽

10.1017/s007418090007618x ◽

1985 ◽

Vol 107 ◽

pp. 559-559

Author(s):

V. A. Mazur ◽

A. V. Stepanov

Keyword(s):

Magnetic Field ◽

Wave Dispersion ◽

Alfven Waves ◽

Alfven Wave ◽

Wave Number ◽

Alfvén Waves ◽

Coronal Loops ◽

Coronal Magnetic Loops ◽

The Magnetic Field ◽

Solar Coronal

It is shown that the existence of plasma density inhomogeneities (ducts) elongated along the magnetic field in coronal loops, and of Alfven wave dispersion, associated with the taking into account of gyrotropy U ≡ ω/ωi ≪ 1 (Leonovich et al., 1983), leads to the possibility of a quasi-longitudinal k⊥ < √U k‖ propagation (wave guiding) of Alfven waves. Here ω is the frequency of Alfven waves, ωi is the proton gyrofrequency, and k is the wave number. It is found that with the parameter ξ = ω2 R/ωi A > 1, where R is the inhomogeneity scale of a loop across the magnetic field, and A is the Alfven wave velocity, refraction of Alfven waves does not lead, as contrasted to Wentzel's inference (1976), to the waves going out of the regime of quasi-longitudinal propagation. As the result, the amplification of Alfven waves in solar coronal loops can be important. A study is made of the cyclotron instability of Alfven waves under solar coronal conditions.

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Excitation of kinetic Alfvén turbulence by MHD waves and energization of space plasmas

Nonlinear Processes in Geophysics ◽

10.5194/npg-11-535-2004 ◽

2004 ◽

Vol 11 (5/6) ◽

pp. 535-543 ◽

Cited By ~ 23

Author(s):

Y. Voitenko ◽

M. Goossens

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Energy Transport ◽

Plasma Heating ◽

Alfven Wave ◽

Mhd Waves ◽

Space Plasmas ◽

Small Scale ◽

The Magnetic Field ◽

Dissipation Range

Abstract. There is abundant observational evidence that the energization of plasma particles in space is correlated with an enhanced activity of large-scale MHD waves. Since these waves cannot interact with particles, we need to find ways for these MHD waves to transport energy in the dissipation range formed by small-scale or high-frequency waves, which are able to interact with particles. In this paper we consider the dissipation range formed by the kinetic Alfvén waves (KAWs) which are very short- wavelengths across the magnetic field irrespectively of their frequency. We study a nonlocal nonlinear mechanism for the excitation of KAWs by MHD waves via resonant decay AW(FW)→KAW1+KAW2, where the MHD wave can be either an Alfvén wave (AW), or a fast magneto-acoustic wave (FW). The resonant decay thus provides a non-local energy transport from large scales directly in the dissipation range. The decay is efficient at low amplitudes of the magnetic field in the MHD waves, B/B0~10-2. In turn, KAWs are very efficient in the energy exchange with plasma particles, providing plasma heating and acceleration in a variety of space plasmas. An anisotropic energy deposition in the field-aligned degree of freedom for the electrons, and in the cross-field degrees of freedom for the ions, is typical for KAWs. A few relevant examples are discussed concerning nonlinear excitation of KAWs by the MHD wave flux and consequent plasma energization in the solar corona and terrestrial magnetosphere.

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Plasma Heating by Alfvén Waves - Kinetic Properties of Magnetohydrodynamic Disturbances

Symposium - International Astronomical Union ◽

10.1017/s0074180900075860 ◽

1985 ◽

Vol 107 ◽

pp. 381-389

Author(s):

Akira Hasegawa

Keyword(s):

Electric Field ◽

Plasma Heating ◽

Alfven Wave ◽

Larmor Radius ◽

Alfvén Waves ◽

Kinetic Properties ◽

Parallel Electric Field ◽

Astrophysical Plasmas ◽

Finite Larmor Radius ◽

Wave Heating

Mechanisms of Alfvén wave heating in space-astrophysical plasmas are presented with particular emphasis on the parallel electric field generated in the magnetohydrodynamic perturbations due to the finite Larmor radius effects.

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Concerning the Dynamics of Energetic Protons in Coronal Magnetic Loops: Dispersion Effects of Alfven Waves

Symposium - International Astronomical Union ◽

10.1017/s0074180900076105 ◽

1985 ◽

Vol 107 ◽

pp. 559-559

Author(s):

V. A. Mazur ◽

A. V. Stepanov

Keyword(s):

Magnetic Field ◽

Wave Dispersion ◽

Alfven Waves ◽

Alfven Wave ◽

Wave Number ◽

Alfvén Waves ◽

Coronal Loops ◽

Coronal Magnetic Loops ◽

The Magnetic Field ◽

Solar Coronal

It is shown that the existence of plasma density inhomogeneities (ducts) elongated along the magnetic field in coronal loops, and of Alfven wave dispersion, associated with the taking into account of gyrotropy U ≡ ω/ωi ≪ 1 (Leonovich et al., 1983), leads to the possibility of a quasi-longitudinal k⊥ < √U k‖ propagation (wave guiding) of Alfven waves. Here ω is the frequency of Alfven waves, ωi is the proton gyrofrequency, and k is the wave number. It is found that with the parameter ξ = ω2 R/ωi A > 1, where R is the inhomogeneity scale of a loop across the magnetic field, and A is the Alfven wave velocity, refraction of Alfven waves does not lead, as contrasted to Wentzel's inference (1976), to the waves going out of the regime of quasi-longitudinal propagation. As the result, the amplification of Alfven waves in solar coronal loops can be important. A study is made of the cyclotron instability of Alfven waves under solar coronal conditions.

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