Modulation of Whistler Mode Waves by Ultra‐Low Frequency Wave in a Macroscale Magnetic Hole: MMS Observations

He, Zhang; Zhong, Zhihong; Tang, Rongxin; Deng, Xiaohua; Li, Haimeng; Wang, Dedong

doi:10.1029/2021gl096056

Cited by 14 publications

(26 citation statements)

References 62 publications

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“…These waves correspond to a positive ellipticity (which approaches 1 as shown in Figure 2(j)), and wave normal angles tend to be quasi-parallel (θ < 15°, Figure 2(k)). Thus, we conclude that the wave emissions at the DF correspond to the right-hand polarized and parallel propagation whistler-mode waves (Tang et al 2014;Tang & Summers 2019;Zhang et al 2021;Zhong et al 2021). Figure 2(l) shows that the Poynting flux of whistler-mode waves has two propagation directions (parallel and antiparallel to the background magnetic field), which should be indicators of wave source regions.…”

Section: Overviewmentioning

confidence: 81%

“…The mirror-mode structure can effectively affect the electron kinetics and energy exchange between the plasma and the background field (Huang et al 2017;Zhong et al 2019b), and it is usually observed that whistler-mode waves are generated around it (Kitamura et al 2020;Zhang et al 2021). For the mirror-mode structure before the DF, it is usually considered to be due to the ion particles reflected and accelerated by the DF (Wang et al 2016a), and the magnetic pileup ahead of the DF (Zieger et al 2011).…”

Section: Discussion and Summarymentioning

confidence: 99%

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Observations of Whistler-mode Waves and Large-amplitude Electrostatic Waves Associated with a Dipolarization Front in the Bursty Bulk Flow

Zhang

Zhong

Tang

et al. 2022

ApJ

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Plasma jets and jet fronts are common phenomena in planetary magnetospheres. They are usually associated with many plasma waves and can play a key role in the energy conversion, the excitation of wave emissions, particle acceleration, and the evolution of many astrophysical phenomena, which are major issues in the study of helio-terrestrial space physics. In this paper, we carefully investigated the properties of the whistler-mode wave and large-amplitude electrostatic wave in a plasma jet (bursty bulk flow (BBF)) using the Magnetospheric Multiscale mission data on the Earth's magnetosphere. At the leading part of the BBF, intense whistler-mode waves were observed inside the ion mirror-mode structures, which should be excited by the perpendicular temperature anisotropy of trapping electrons. A small-scale dipolarization front (DF) was then observed at the center of this BBF as a boundary between the leading and trailing parts of the BBF. Behind the DF, both an ion mirror-mode structure and whistler-mode waves disappear, while a large-amplitude electrostatic wave was detected and was associated with the cold ions at the trailing part of the BBF. The electrostatic wave is supposed to be generated by ion beam instability. These results will significantly improve the understanding of the kinetic process associated with the important boundary layer DF within plasma jets. The corresponding wave–particle interaction in space and the plasma environment can be further understood.

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Section: Overviewmentioning

confidence: 81%

Section: Discussion and Summarymentioning

confidence: 99%

Observations of Whistler-mode Waves and Large-amplitude Electrostatic Waves Associated with a Dipolarization Front in the Bursty Bulk Flow

Zhang

Zhong

Tang

et al. 2022

ApJ

Self Cite

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“…The minimized sum of squared residuals is only 0.04 on a logarithmic scale, indicating a good approximation to the real MMS VDF data. In fact, by comparing to previous models which include a number of bi-Maxwellian components [35,36], we find our model is a simple and efficient treatment.…”

Section: Vdf Model and The Arbitrary Linear Plasma Solver (Alps)mentioning

confidence: 85%

“…Whistler waves are frequently observed in magnetic holes, but the excitation and origin of these waves are a matter of ongoing research [28][29][30]. Recently, so-called pancake, donut-shaped, or butterfly pitch-angle distributions with beams of electrons have been proposed as sources for the wave excitation [31][32][33][34][35][36]. However, there is still a lack of consistent evidence supporting these mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Whistler Waves As a Signature of Converging Magnetic Holes in Space Plasmas

Jiang

Verscharen

et al. 2022

Preprint

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Magnetic holes are plasma structures that trap a large number of particles in a magnetic field that is weaker than the field in its surroundings. The unprecedented high time-resolution observations by NASA's Magnetospheric Multi-Scale (MMS) mission enable us to study the particle dynamics in magnetic holes in the Earth's magnetosheath in great detail. For the first time, we reveal the local generation mechanism of whistler waves by a Landau-resonant instability of electron beams in response to the large-scale evolution of a magnetic hole. As the magnetic hole converges, a pair of counter-streaming electron beams form near the hole's center as a consequence of the combined action of betatron and Fermi effects. The beams trigger the generation of slightly-oblique whistler waves. Our model is supported by a remarkable agreement between our observations and numerical predictions from the Arbitrary Linear Plasma Solver (ALPS). Our study shows that wave-particle interactions are fundamental to the evolution of magnetic holes in space and astrophysical plasmas.

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“…Kitamura et al (2020) observed whistlers inside mirror modes of size ∼2,600 km ≈ 43d i in the Q ⊥ MSH, and simultaneously observed butterflies which they identified as the source of the waves. H. Zhang et al (2021) found whistler waves generated by electron butterfly distributions inside a magnetic hole of size ∼2,400 km ≈ 26d i close to the magnetopause. These previous reports have mainly been focused on the Q ⊥ MSH, where magnetic minima (of size tens of ion inertial lengths) due to mirror modes are common.…”

Section: Discussionmentioning

confidence: 99%

Kinetic Generation of Whistler Waves in the Turbulent Magnetosheath

Svenningsson

Yordanova

Cozzani

et al. 2022

Geophysical Research Letters

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The Earth's magnetosheath (MSH) is the space plasma region downstream of the bow shock where solar wind plasma is heated, slowed down, and deflected around the magnetosphere. Numerous physical processes take place in the MSH, among which are pitch-angle scattering from wave-particle interactions (He et al., 2019), and particle trapping (Ahmadi et al., 2018;Yao et al., 2018), which shape the velocity distributions of the electrons and ions and contribute to the heating of the plasma. Understanding these processes and the conditions in which they arise is an active research topic.The conditions in the MSH depend on the geometry of the bow shock, where it is common to differentiate between two different cases: quasi-parallel (Q ‖ ) and quasi-perpendicular (Q ⊥ ). In the Q ⊥ case, the shock normal angle θ bn (the angle between the bow shock normal direction and the interplanetary magnetic field (IMF)) is larger than 45° (Balogh et al., 2005). Typical for this region is ion pressure anisotropy which favors the mirror mode instability (Dimmock et al., 2015), and particle energization is mainly caused by compression. In the Q ‖ case, θ bn < 45°. Since the MSH is magnetically connected to the IMF, it strongly interacts with the upstream transients and discontinuities hitting the bow shock. The Q ‖ MSH is characterized by significant variations in the magnetic field, particle velocity, density, and temperature. The fluctuations of the plasma parameters have larger amplitude than in the Q ⊥ case. Current sheets (Vörös et al., 2016;Yordanova et al., 2020), high speed jets (Hietala Abstract The Earth's magnetosheath (MSH) is governed by numerous physical processes which shape the particle velocity distributions and contribute to the heating of the plasma. Among them are whistler waves which can interact with electrons. We investigate whistler waves detected in the quasi-parallel MSH by NASA's Magnetospheric Multiscale mission. We find that the whistler waves occur even in regions that are predicted stable to wave growth by electron temperature anisotropy. Whistlers are observed in ion-scale magnetic minima and are associated with electrons having butterfly-shaped pitch-angle distributions. We investigate in detail one example and, with the support of modeling by the linear numerical dispersion solver Waves in Homogeneous, Anisotropic, Multicomponent Plasmas, we demonstrate that the butterfly distribution is unstable to the observed whistler waves. We conclude that the observed waves are generated locally. The result emphasizes the importance of considering complete 3D particle distribution functions, and not only the temperature anisotropy, when studying plasma wave instabilities. Plain Language SummaryThe magnetosheath (MSH) is the region downstream of the Earth's bow shock where solar wind plasma is slowed down, heated, and deflected around the magnetosphere. The angle between the interplanetary magnetic field and the bow shock normal direction determines the properties of the MSH leading to the formation of two distinct c...

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Modulation of Whistler Mode Waves by Ultra‐Low Frequency Wave in a Macroscale Magnetic Hole: MMS Observations

Abstract: The magnetic hole (MH), a quasi-stable magnetic structure characterized by the significant decreases of magnitude field, have been widely reported in solar wind (

Cited by 14 publications

References 62 publications

Observations of Whistler-mode Waves and Large-amplitude Electrostatic Waves Associated with a Dipolarization Front in the Bursty Bulk Flow

Observations of Whistler-mode Waves and Large-amplitude Electrostatic Waves Associated with a Dipolarization Front in the Bursty Bulk Flow

Whistler Waves As a Signature of Converging Magnetic Holes in Space Plasmas

Kinetic Generation of Whistler Waves in the Turbulent Magnetosheath

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