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

Voitenko, Yuriy

doi:10.1029/2004ja010874

Cited by 17 publications

(11 citation statements)

References 48 publications

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“…Several damping mechanisms can contribute to the −0.13 decrement, including Landau damping, ion cyclotron damping, nonadiabatic/stochastic heating, etc. [see, e.g., Quataert, 1998;Voitenko and Goossens, 2004;Chandran et al, 2010]. This conclusion is supported by the two-fluid simulations by Boldyrev and Perez [2012] giving the spectral index ∼ −8∕3, similar to the observed indices and to the index ∼ −2.8 found in gyrokinetic simulations [Howes et al, 2011a;TenBarge and Howes, 2013].…”

Section: Damping Effectssupporting

confidence: 74%

Kinetic Alfvén turbulence below and above ion cyclotron frequency

Zhao

Voitenko

et al. 2016

JGR Space Physics

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Alfvénic turbulent cascade perpendicular and parallel to the background magnetic field is studied accounting for anisotropic dispersive effects and turbulent intermittency. The perpendicular dispersion and intermittency make the perpendicular‐wave‐number magnetic spectra steeper and speed up production of high ion cyclotron frequencies by the turbulent cascade. On the contrary, the parallel dispersion makes the spectra flatter and decelerate the frequency cascade above the ion cyclotron frequency. Competition of these factors results in spectral indices distributed in the interval [−2, −3], where −2 is the index of high‐frequency space‐filling turbulence and −3 is the index of low‐frequency intermittent turbulence formed by tube‐like fluctuations. Spectra of fully intermittent turbulence fill a narrower range of spectral indices [−7/3, −3], which almost coincides with the range of indexes measured in the solar wind. This suggests that the kinetic‐scale turbulent spectra are mainly shaped by the dispersion and intermittency. A small mismatch with measured indexes of about 0.1 can be associated with damping effects not studied here.

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Section: Damping Effectssupporting

confidence: 74%

Kinetic Alfvén turbulence below and above ion cyclotron frequency

Zhao

Voitenko

et al. 2016

JGR Space Physics

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“…This heating mechanism prefers heavy ions, which is supported by the measurements reported in this paper. Our results may be directly applicable to the currently disputed problem of ion heating in the solar corona [8,9] and ion energization in magnetospheric plasmas [10].…”

mentioning

confidence: 88%

Acceleration of solar wind ions to 1 MeV by electromagnetic structures upstream of the Earth's bow shock

Stasiewicz

Eliasson

Strumik

et al. 2013

EPL

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PACS 95.30.Qd -Magnetohydrodynamics and plasmas PACS 47.35.Fg -Solitary waves PACS 52.50.Lp -Plasma production and heating by shock waves and compression Abstract -We present measurements from the ESA/NASA Cluster mission that show in situ acceleration of ions to energies of 1 MeV outside the bow shock. The observed heating can be associated with the presence of electromagnetic structures with strong spatial gradients of the electric field that lead to ion gyro-phase breaking and to the onset of chaos in ion trajectories. It results in rapid, stochastic acceleration of ions in the direction perpendicular to the ambient magnetic field. The electric potential of the structures can be compared to a field of moguls on a ski slope, capable of accelerating and ejecting the fast running skiers out of piste. This mechanism may represent the universal mechanism for perpendicular acceleration and heating of ions in the magnetosphere, the solar corona and in astrophysical plasmas. This is also a basic mechanism that can limit steepening of nonlinear electromagnetic structures at shocks and foreshocks in collisionless plasmas.Introduction. -It is generally believed that the acceleration of particles to super thermal energies in the inner heliosphere is done mainly by shock waves [1,2]. These may be driven by solar flares and coronal mass ejections, and are also formed at planetary bow shocks, and at boundaries between streams of fast and slow solar wind plasma in co-rotating interaction regions [3,4]. The origin of the energetic ions observed upstream of the Earth's bow shock [5] is generally attributed to shock drift acceleration [6] of solar ions or to leakage from the magnetosphere [7]. In this letter, we present measurements that show in situ acceleration of ions to energies of 1 MeV outside the bow shock, incompatible with both the concepts of leakage and shock drift acceleration. The observed heating can be associated with the presence of electromagnetic structures with gradients of the electric field that lead to ion gyro-phase breaking and to rapid, stochastic acceleration of ions in the direction perpendicular to the ambient magnetic field. This heating mechanism prefers heavy ions, which is supported by the measurements reported in this paper. Our results may be directly

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“…Because of the relatively high frequency, the Alfvén waves from the Spectrum II undergo relatively strong phase mixing and transform into KAWs. In a hydrogen plasma with β > m e /m p (β is the gas/magnetic pressure ratio, m e /m p is the electron/proton mass ratio), the KAW dispersion and the Cherenkov (Landau) damping/growth rate are given by Voitenko (1998) …”

Section: Coronal Alfvén Wavesmentioning

confidence: 99%

“…The electromagnetic fields are normalized by B 0 (e.g.,Ē x = E x /B 0 ), and the time is normalized by the proton gyroperiod −1 p = m p c/(eB 0 ), τ = p t. By the use of anisotropic properties of KAWs, ∂/∂z ∂/∂ x, E z E x , the equation for the x-component of ion velocity can be reduced to (Voitenko and Goossens, 2004) …”

Section: Non-adiabatic Acceleration Of Ions: Analysis Of Initial Phasementioning

confidence: 99%

“…In the framework of the electrostatic KAW model, Stasiewicz et al (2000b) have shown that KAWs with sufficiently large E ⊥ and/or k ⊥ can make ion trajectories stochastic, which would result in cross-field ion heating. Voitenko and Goossens (2004) studied the ion motion in the electromagnetic KAW fields and found that the stochastization itself (i.e., divergence of ion trajectories) is of minor importance for cross-field ion energization in comparison to the bulk non-adiabatic acceleration of ions in the vicinity of demagnetizing KAW phases. The presence of a magnetic field in KAWs enforces the acceleration of the ions moving along magnetic field against waves.…”

Section: Introductionmentioning

confidence: 99%

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Energization of Plasma Species by Intermittent Kinetic Alfvén Waves

Voitenko

Goossens

2006

Space Sci Rev

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We propose a new phase-mixing sweep model of coronal heating and solar wind acceleration based on dissipative properties of kinetic Alfvén waves (KAWs). The energy reservoir is provided by the intermittent ∼1 Hz MHD Alfvén waves excited at the coronal base by magnetic restructuring. These waves propagate upward along open magnetic field lines, phase-mix, and gradually develop short wavelengths across the magnetic field. Eventually, at 1.5-4 solar radii they are transformed into KAWs. We analyze several basic mechanisms for anisotropic energization of plasma species by KAWs and find them compatible with observations. In particular, UVCS (onboard SOHO) observations of intense cross-field ion energization at 1.5-4 solar radii can be naturally explained by non-adiabatic ion acceleration in the vicinity of demagnetizing KAW phases. The ion cyclotron motion is destroyed there by electric and magnetic fields of KAWs.

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

Cited by 17 publications

References 48 publications

Kinetic Alfvén turbulence below and above ion cyclotron frequency

Kinetic Alfvén turbulence below and above ion cyclotron frequency

Acceleration of solar wind ions to 1 MeV by electromagnetic structures upstream of the Earth's bow shock

Energization of Plasma Species by Intermittent Kinetic Alfvén Waves

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