Generation of Ion Cyclotron Waves in Coronal Holes by a Global Resonant Magnetohydrodynamic Mode

Markovskii, S. A.

doi:10.1086/321641

Cited by 47 publications

(50 citation statements)

References 40 publications

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“…However, in the case of higher wave frequencies, f $ 1 Hz, considered in our model, the reduced reflection makes the turbulence dissipation negligible, as is illustrated by Dmitruk and Matthaeus [2003, Figure 7]. Nonlocal transport due to current instabilities [Markovskii, 2001;Markovskii and Hollweg, 2002] can only be efficient when the MHD waves have strong shear flows or currents. Hence this type of transport requires prestructured Alfvén waves with sufficiently small scales either across the background magnetic field or in the field-aligned direction (which in turn implies already high-frequency Alfvén waves).…”

Section: Introductionmentioning

confidence: 75%

“…The direct turbulent cascade toward higher frequencies [Hollweg, 1986;Tu and Marsch, 1997], and the generation by currents carried by MHD waves [Markovskii, 2001;Markovskii and Hollweg, 2002] have been proposed as local and nonlocal transport mechanisms of wave energy to the ion-cyclotron dissipation range. However, under the solar corona conditions the turbulent cascade is anisotropic and proceeds toward high cross-field wave numbers rather than to high field-aligned wave numbers required for ion-cyclotron resonance .…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear coupling of Alfvén waves with widely different cross‐field wavelengths in space plasmas

Voitenko

2005

J. Geophys. Res.

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[1] Multiscale activity and dissipation of Alfvén waves play an important role in a number of space and astrophysical plasmas. A popular approach to study the evolution and damping of MHD Alfvén waves assumes a gradual evolution of the wave energy to small dissipative length scales. This can be done by local nonlinear interactions among MHD waves with comparable wavelengths resulting in turbulent cascades or by phase mixing and resonant absorption. We investigate an alternative nonlocal transport of wave energy from large MHD length scales directly into the dissipation range formed by the kinetic Alfvén waves (KAWs). KAWs have very short wavelengths across the magnetic field irrespectively of their frequency. We focus on the nonlinear mechanism for the excitation of KAWs by MHD Alfvén waves via resonant decay AW ! KAW 1 + KAW 2 . The resonant decay conditions can be satisfied in a rarified plasmas, where the gas/ magnetic pressure ratio is less than the electron/ion mass ratio. The decay is efficient at low amplitudes of the magnetic field in the MHD waves, B/B 0 $ 10 À2. In turn, the nonlinearly driven KAWs have sufficiently short wavelengths for the dissipative effects to become significant. Therefore the cross-scale nonlinear coupling of Alfvén waves can provide a mechanism for the replenishment of the dissipation range and the consequent energization in space plasmas. Two relevant examples of this scenario in the solar corona and auroral zones are discussed.

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Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Nonlinear coupling of Alfvén waves with widely different cross‐field wavelengths in space plasmas

Voitenko

2005

J. Geophys. Res.

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“…The ion cyclotron resonance and the ion cyclotron mode have been discussed in the context of problems related to the heating of the solar corona, e.g., Marsch et al (1982), Cranmer et al (1999), Cranmer (2000), Tu & Marsch (2001), Markovskii (2001), Isenberg (2001), Hollweg & Isenberg (2002). This is due to various reasons, such as the evidence obtained from in situ measurements in the solar wind and coronal holes of resonant ion cyclotron heating (Hollweg & Isenberg 2002), and a preferential heating of coronal ions (with respect to electrons) which is most dominant in the direction perpendicular to the magnetic field lines.…”

Section: Introductionmentioning

confidence: 99%

Growing drift-cyclotron modes in the hot solar atmosphere

Vranjes

Poedts

2008

A&A

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Context. The ion cyclotron (IC) wave has been discussed in the literature in the context of the solar coronal heating. This is partly due to the necessity of explaining the observed preferential heating in the direction perpendicular to magnetic field lines. Observations have also shown the existence of filamentary density structures of various cross sections in the solar atmosphere. The presence of the related density gradients implies the possibility for the development of drift wave (DW) instability. Aims. The frequencies of the two modes (IC and DW) are usually well separated, however, they can become close to each other for short inhomogeneity scale lengths of the equilibrium density. In this case, the drift wave can effectively couple to the ion cyclotron mode, and in the present work we want to demonstrate this coupling in the parameter domain relevant for the solar corona. Methods. Well-known analytical results which follow from the kinetic theory are used and the dispersion equation, which describes coupled ion cyclotron and drift waves, is solved numerically. Results. The numerical results obtained by using the values for the plasma density, magnetic field and temperature applicable to the solar corona clearly show the coupling and the instability (growing) of the two modes. The coupling happens at very short wavelengths, that are of the order of the ion gyro radius, and for characteristic scale lengths of the equilibrium density that are altitude dependent and may become of the order of only a few meters. Conclusions. The demonstrated instability of the two coupled modes (driven by the equilibrium density gradient) is obtained by using a rigorous kinetic theory model and for realistic parameter values. The physical mechanism which is behind the coupling is simple and is expected to take place throughout the solar atmosphere and the solar wind which contain a variety of very elongated density structures of various sizes. The mode grows on account of the density gradient, it is essentially an ion mode, and its further dissipation should result in an increased ion heating.

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“…We need to compare the energy budget of the solar wind and the threshold of the instability. At the coronal base the degree of intermittency turns out to be around several hundred (Markovskii andHollweg, 2002b, 2003).…”

Section: Basic Conceptsmentioning

confidence: 99%

“…Alternatively, the ion cyclotron waves can be excited by the plasma instability driven by currents associated with a global MHD mode (Markovskii, 2001). A similar idea was used by Viñas et al (2000) to explain electron heating in the corona.…”

Section: Introductionmentioning

confidence: 99%

Radial evolution of intermittent heat flux in solar coronal holes

Markovskii

Hollweg

2004

Nonlin. Processes Geophys.

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Abstract. Recently, we suggested that the source of ion heating in solar coronal holes is small-scale reconnection events (microflares) at the coronal base. The microflares launch intermittent heat flux up into the corona exciting ion cyclotron waves through a plasma microinstability. The ions are heated by these waves during the microflare bursts and then evolve with no energy input between the bursts. The overall coronal heating by this mechanism is a summed effect of all microflare bursts during the expansion time of the solar wind and adiabatic cooling between the microflares. The intermittent heat flux produced by the microflares was modeled as electron beams with constant speed and temperature for simplicity. In this paper, we consider a more sophisticated model of the heat flux taking into account the action of the mirror force and the charge separation electric field on the beam particles. We show that the radial evolution of the heat flux is determined mainly by the beam expansion along the magnetic field roughly at the root mean square velocity of the beam particles, while the variation of the beam bulk speed and thermal energy is less important.

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Generation of Ion Cyclotron Waves in Coronal Holes by a Global Resonant Magnetohydrodynamic Mode

Cited by 47 publications

References 40 publications

Nonlinear coupling of Alfvén waves with widely different cross‐field wavelengths in space plasmas

Nonlinear coupling of Alfvén waves with widely different cross‐field wavelengths in space plasmas

Growing drift-cyclotron modes in the hot solar atmosphere

Radial evolution of intermittent heat flux in solar coronal holes

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