Whistler‐mode waves inside flux pileup region: Structured or unstructured?

Fu, H. S.; Cao, Jinbin; Cully, C. M.; Khotyaintsev, Yuri V.; Vaivads, A.; Angelopoulos, V.; Zong, Qiugang; Santolı́k, O.; Macúšová, E.; André, Mats; Liu, Wenlong; Lu, Haoyu; Zhou, Meng; Huang, Suming; Zhima, Zeren

doi:10.1002/2014ja020204

Cited by 114 publications

(101 citation statements)

References 58 publications

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“…The B Z fluctuations could be related to MHD waves, which are often observed near DFs (e.g., Zhou et al, 2014). But as was reported by Zhou et al (2014), the amplitude of these waves ≤ 2 nT. In our event the amplitude of strong B Z pulses exceeds 5 nT.…”

Section: Data Descriptionsupporting

confidence: 65%

“…During the gradual growth of B Z , numerous pulses of positive B Z field were observed. The B Z fluctuations could be related to MHD waves, which are often observed near DFs (e.g., Zhou et al, 2014). But as was reported by Zhou et al (2014), the amplitude of these waves ≤ 2 nT.…”

Section: Data Descriptionmentioning

confidence: 73%

“…The last may lead to additional energization and/or particles scattering and losses via processes of wave-particle interactions (e.g., Le Contel et al, 2009;Zhou et al, 2009;Deng et al, 2010;Khotyaintsev et al, 2011;Panov et al, 2013;Fu et al, 2014;Vilberg et al, 2014;Zhang and Angelopoulos, 2014;Grigorenko et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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Abstract. The fortunate location of Cluster and the THEMIS P3 probe in the near-Earth plasma sheet (PS) (at X ∼ −7-−9 R E ) allowed for the multipoint analysis of properties and spectra of electron and proton injections. The injections were observed during dipolarization and substorm current wedge formation associated with braking of multiple bursty bulk flows (BBFs). In the course of dipolarization, a gradual growth of the B Z magnetic field lasted ∼ 13 min and it was comprised of several B Z pulses or dipolarization fronts (DFs) with duration ≤ 1 min. Multipoint observations have shown that the beginning of the increase in suprathermal (> 50 keV) electron fluxes -the injection boundary -was observed in the PS simultaneously with the dipolarization onset and it propagated dawnward along with the onset-related DF. The subsequent dynamics of the energetic electron flux was similar to the dynamics of the magnetic field during the dipolarization. Namely, a gradual linear growth of the electron flux occurred simultaneously with the gradual growth of the B Z field, and it was comprised of multiple short (∼ few minutes) electron injections associated with the B Z pulses. This behavior can be explained by the combined action of local betatron acceleration at the B Z pulses and subsequent gradient drifts of electrons in the flux pile up region through the numerous braking and diverting DFs. The nonadiabatic features occasionally observed in the electron spectra during the injections can be due to the electron interactions with high-frequency electromagnetic or electrostatic fluctuations transiently observed in the course of dipolarization.On the contrary, proton injections were detected only in the vicinity of the strongest B Z pulses. The front thickness of these pulses was less than a gyroradius of thermal protons that ensured the nonadiabatic acceleration of protons. Indeed, during the injections in the energy spectra of protons the pronounced bulge was clearly observed in a finite energy range ∼ 70-90 keV. This feature can be explained by the nonadiabatic resonant acceleration of protons by the bursts of the dawn-dusk electric field associated with the B Z pulses.

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Section: Data Descriptionsupporting

confidence: 65%

Section: Data Descriptionmentioning

confidence: 73%

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Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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“…Figures 4f and 4g show the electron phase space densities (PSD) f e in the EDR at 07:43:30.304 UT. In previous studies, streaming instabilities [Divin et al, 2012] and the associated electron holes [Goldman et al, 2014] at separatrices and the perpendicular anisotropy of suprathermal electrons [e.g., Khotyaintsev et al, 2011;Fu et al, 2014] have been suggested as two possible mechanisms responsible for the generation of whistlers. For the low-energy electrons (E < 100 eV), the PSD at θ = 180°is slightly larger than that at θ = 0°and θ = 90°(see Figure 4f), while for the medium-energy electrons (E > 100 eV), the PSD tends to be dominant in the perpendicular direction (Figure 4g).…”

Section: Electron Distribution and Wave Generationmentioning

confidence: 99%

MMS observations of whistler waves in electron diffusion region

Cao

et al. 2017

Geophysical Research Letters

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Whistler waves that can produce anomalous resistivity by affecting electrons' motion have been suggested as one of the mechanisms responsible for magnetic reconnection in the electron diffusion region (EDR). Such type of waves, however, has rarely been observed inside the EDR so far. In this study, we report such an observation by Magnetospheric Multiscale (MMS) mission. We find large‐amplitude whistler waves propagating away from the X line with a very small wave‐normal angle. These waves are probably generated by the perpendicular temperature anisotropy of the ~300 eV electrons inside the EDR, according to our analysis of dispersion relation and cyclotron resonance condition; they significantly affect the electron‐scale dynamics of magnetic reconnection and thus support previous simulations.

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“…DFs play a significant role in the magnetospheric dynamics (Zhou et al, 2010;Fu et al, 2011Fu et al, , 2012cFu et al, , 2014Ge et al, 2012;Hwang et al, 2014;Wang et al, 2016). The energetic ion anisotropies in the near-Earth plasma sheet show no strong correlation with Auroral Electrojet (AE) index, indicating that its acceleration sources are localized (Luo et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

et al. 2017

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Abstract. We investigate the occurrence rate of dipolarization fronts (DFs) in the plasma sheet by taking full advantage of all four Cluster satellites (C1-4) from years 2001 to 2009. In total, we select 466 joint-observation DF events, in which 318, 282, 254, and 236 DFs are observed by C1, C2, C3, and C4, respectively. Our findings are as follows: (1) the maximum occurrence rate is ∼ 15.3 events per day at X ∼ 15 R E in the XY plane, and the average occurrence rate is ∼ 5.4 events per day over the whole observation period; (2) the occurrence rate on the dusk side of the plasma sheet is larger and decreases with increasing B XY /B Lobe ; (3) the occurrence rate within |Y | < 6 R E increases gradually from X ≈ −19 to −15 R E and then decreases from X ≈ −15 to −10 R E ; (4) the occurrence rate when AE > 200 nT is much larger than that when AE < 200 nT, indicating that DFs preferentially occur during high geomagnetic activity. The magnetic pileup and earthward and duskward ion flows could contribute to the increases in the occurrence rate from X ≈ −19 to −15 R E . We suggest that both geomagnetic activity and multiple DFs contribute to the high occurrence rate of the DFs. In addition, the finite length of the DF in the dawn-dusk direction can affect the chance that a satellite observes the DF.

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Whistler‐mode waves inside flux pileup region: Structured or unstructured?

Cited by 114 publications

References 58 publications

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

MMS observations of whistler waves in electron diffusion region

Occurrence rate of dipolarization fronts in the plasma sheet: Cluster observations

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