Modulation of Ion and Electron Pitch Angle in the Presence of Large-amplitude, Low-frequency, Left-hand Circularly Polarized Electromagnetic Waves Observed by MMS

Zhao, Jinsong; Wang, T. Y.; Dunlop, M. W.; He, Jiansen; Dong, Xiangcheng; Wu, D. J.; Khotyaintsev, Yuri; Ergun, R. E.; Russell, C. T.; Giles, B. L.; Torbert, R. B.; Burch, J. L.

doi:10.3847/1538-4357/aae097

Cited by 13 publications

(7 citation statements)

References 25 publications

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“…One is wave-particle interactions, such as cyclotron and Landau resonances with kinetic Alfvén and slow-mode waves (He et al 2015a,b). In a more recent paper, modulations of the ion and electron pitch angle in the presence of large-amplitude electromagnetic waves are also found (Zhao et al 2018). The other is dissipation near coherent structures (Osman et al 2012b;Wan et al 2012;Pezzi et al 2016).…”

Section: Energy Conversion Channels Associated With the Alfve ń Vortexmentioning

confidence: 94%

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Wang

Alexandrova

Perrone

et al. 2019

ApJL

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Alfvén vortex is a multi-scale nonlinear structure which contributes to intermittency of turbulence. Despite previous explorations mostly on the spatial properties of the Alfvén vortex (i.e., scale, orientation, and motion), the plasma characteristics within the Alfvén vortex are unknown. Moreover, the connection between the plasma energization and the Alfvén vortex still remains unclear. Based on high resolution in-situ measurement from the Magnetospheric Multiscale (MMS) mission, we report for the first time, distinctive plasma features within an Alfvén vortex. This Alfvén vortex is identified to be two-dimensional (k ⊥ k ) quasi-monopole with a radius of 10 proton gyroscales. Its magnetic fluctuations δB ⊥ are anti correlated with velocity fluctuations δV ⊥ , thus the parallel current density j and flow vorticity ω are anti-aligned. In different part of the vortex (i.e., edge, middle, center), the ion and electron temperatures are found to be quite different and they behave in the reverse trend: the ion temperature variations are correlated with j , while the electron temperature variations are correlated with ω . Furthermore, the temperature anisotropies, together with the non-Maxwellian kinetic effects, exhibit strong enhancement at peaks of |ω |(|j |) within the vortex. Comparison between observations and numerical/theoretical results are made. In addition, the energy-conversion channels and the compressibility associated with the Alfvén vortex are discussed. These results may help to understand the link between coherent vortex structures and the kinetic processes, which determines how turbulence energy dissipate in the weakly-collisional space plasmas.

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Section: Energy Conversion Channels Associated With the Alfve ń Vortexmentioning

confidence: 94%

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Wang

Alexandrova

Perrone

et al. 2019

ApJL

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“…Furthermore, a statistical analysis from AMPTE/IRM spacecraft proposed that EMIC waves contribute mainly to electromagnetic fluctuations downstream of the quasi‐perpendicular low‐beta shocks and the average relative amplitude δB / B 0 is around 0.08 (Czaykowska et al, ). Recently, Zhao et al () applied the NASA Magnetospheric Multiscale (MMS) mission's high temporal resolution plasma measurements to show modulation of ion and electron pitch angle distribution in the presence of large‐amplitude EMIC waves. These large‐amplitude EMIC waves may play important roles in triggering nonlinear instability and scattering of ions in the magnetosheath (i.e., Alexandrova et al, ; Kitamura et al, ; McKean et al, ).…”

Section: Introductionmentioning

confidence: 99%

Large‐Amplitude Electromagnetic Ion Cyclotron Waves and Density Fluctuations in the Flank of the Earth's Magnetosheath

Zhao

Wang

Dunlop

et al. 2019

Geophysical Research Letters

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The electromagnetic ion cyclotron (EMIC) wave usually observed in the Earth's magnetosheath is thought to be generated through the ion temperature anisotropy instability. This paper presents an observation of a long‐lasting large‐amplitude EMIC wave event in the dawnside flank of the magnetosheath by the Magnetospheric Multiscale mission, lasting from 06:33:00 to 12:35:00 UT on 16 April 2018. The wave amplitude is around 0.2 nT as compared to the ambient magnetic field ~12 nT. The characteristic frequency and scale size are around 0.2 Hz and 1,028 km, respectively. Accompanying EMIC waves are density fluctuations, which exhibit both positive and negative correlations with the longitudinal magnetic field. Using the fitted parameters for the ion and electron phase space densities, plasma kinetic theory predicts local excitations of both EMIC and mirror instabilities, which provide the energy of these observed EMIC waves and density fluctuations.

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“…Because IPDs are computed in the spacecraft frame, most of changes in distributions result from changes in the angle between the magnetic field and the bulk ion flow. Therefore, the large-amplitude EMIC wave can modulate the IPDs (Zhao et al 2018). In interval III, the ion pitch angle is mostly limited in the range of ∼45°-135°.…”

Section: Ion Dynamicsmentioning

confidence: 99%

Ion and Electron Dynamics in the Presence of Mirror, Electromagnetic Ion Cyclotron, and Whistler Waves

Zhao

Wang²,

Shi

et al. 2019

ApJ

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The wave-particle cyclotron interaction is a basic process in collisionless plasmas, which results in the redistribution of the energy between plasma waves and charged particles. This paper presents an event observation in order to explore the dynamics of charged particles and plasma waves, i.e., mirror, electromagnetic ion cyclotron (EMIC), and whistler waves, in the Earth's magnetosheath. It shows that when ions have a high-speed streaming velocity parallel to the magnetic field, EMIC waves arise. We also find that the frequency distribution of nearly parallel and nearly antiparallel whistler waves depends on the parallel streaming velocity of electrons. Based on the linear kinetic theory and the fitting plasma parameters, we show that the differential flows among ion components can enhance the ion cyclotron anisotropy instability that is even stronger than the mirror instability. The differential electron flows induce an asymmetry of the growth rate of counter-propagating whistler waves in the electron cyclotron anisotropy instability. On the other hand, the low-frequency EMIC and transverse electromagnetic waves modulate the ion pitch angle distribution. Moreover, when charged particles flow across the magnetic field, both low-and high-energy electrons are deeply trapped by mirror waves. These results illustrate new features of the observed plasma waves and charged particles in the Earth's magnetosheath, which could inspire improvement of the wave models therein.

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Modulation of Ion and Electron Pitch Angle in the Presence of Large-amplitude, Low-frequency, Left-hand Circularly Polarized Electromagnetic Waves Observed by MMS

Cited by 13 publications

References 25 publications

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Large‐Amplitude Electromagnetic Ion Cyclotron Waves and Density Fluctuations in the Flank of the Earth's Magnetosheath

Ion and Electron Dynamics in the Presence of Mirror, Electromagnetic Ion Cyclotron, and Whistler Waves

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