Lower Hybrid Waves at the Magnetosheath Separatrix Region

Tang, Binbin; Li, W. Y.; Graham, Daniel B.; Wang, C.; Khotyaintsev, Yuri V.; Lê, A.; Giles, B. L.; Lindqvist, Per‐Arne; Ergun, R. E.; Burch, J. L.

doi:10.1029/2020gl089880

Cited by 8 publications

(8 citation statements)

References 50 publications

(78 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In situ measurements show that lower-hybrid waves (LHW) with a frequency close to the lower-hybrid frequency f LH ≈ √ ω ci ω ce /2π, are ubiquitous in magnetized space plasma environments. Such waves are commonly observed at Earth's magnetotail (Huba et al 1978;Retinó et al 2008;Zhou et al 2009Zhou et al , 2014Khotyaintsev et al 2011;Norgren et al 2012;Le Contel et al 2017) and Earth's magnetopause (André et al 2001;Bale et al 2002;Vaivads et al 2004;Graham et al 2017Graham et al , 2019Tang et al 2020). In these two regions, LHW are commonly observed in the vicinity of magnetic reconnection sites where strong density gradients do form.…”

Section: Introductionmentioning

confidence: 98%

Electron acceleration driven by the lower-hybrid-drift instability

Lavorenti

Henri

Califano

et al. 2021

A&A

View full text Add to dashboard Cite

Context. Density inhomogeneities are ubiquitous in space and astrophysical plasmas, particularly at contact boundaries between different media. They often correspond to regions that exhibit strong dynamics across a wide range of spatial and temporal scales. Indeed, density inhomogeneities are a source of free energy that can drive various instabilities such as the lower-hybrid-drift instability, which, in turn, transfers energy to the particles through wave-particle interactions and eventually heats the plasma. Aims. Our study is aimed at quantifying the efficiency of the lower-hybrid-drift instability to accelerate or heat electrons parallel to the ambient magnetic field. Methods. We combine two complementary methods: full-kinetic and quasilinear models. Results. We report self-consistent evidence of electron acceleration driven by the development of the lower-hybrid-drift instability using 3D-3V full-kinetic numerical simulations. The efficiency of the observed acceleration cannot be explained by standard quasilinear theory. For this reason, we have developed an extended quasilinear model that is able to quantitatively predict the interaction between lower-hybrid fluctuations and electrons on long time scales, which is now in agreement with full-kinetic simulations results. Finally, we apply this new, extended quasilinear model to a specific inhomogeneous space plasma boundary, namely, the magnetopause of Mercury. Furthermore, we discuss our quantitative predictions of electron acceleration to support future BepiColombo observations.

show abstract

Section: Introductionmentioning

confidence: 98%

Electron acceleration driven by the lower-hybrid-drift instability

Lavorenti

Henri

Califano

et al. 2021

A&A

View full text Add to dashboard Cite

show abstract

“…In addition to the lower-hybrid drift instability, the relative drift between two ion populations (Graham et al, 2017) or between ions and electrons (Graham et al, 2019) without the effect of the pressure gradient can also induce lower-hybrid waves.The lower-hybrid wave that develops in regions with a strong magnetic field and low plasma 𝐴𝐴 𝐴𝐴 is typically the short-wavelength mode, in which the wave number 𝐴𝐴 𝐴𝐴𝐴𝐴𝑒𝑒 is a fraction of unity. Examples include waves at the boundary of the current sheet (e.g., Le Contel et al, 2017;Norgren et al, 2012;Zhou et al, 2009), in the separatrix region of magnetic reconnection far away from the electron diffusion region (EDR) (the satellite does not encounter the EDR during the current sheet crossing) at the magnetotail (e.g., Holmes et al, 2021), at dayside magnetopause on the magnetospheric side (Graham et al, 2019), and at dayside magnetopause on the magnetosheath side (Tang et al, 2020). The wave propagates mainly in the L-M plane roughly perpendicular to the…”

mentioning

confidence: 99%

Lower‐Hybrid Wave Structures and Interactions With Electrons Observed in Magnetotail Reconnection Diffusion Regions

et al. 2022

Self Cite

View full text Add to dashboard Cite

We investigate waves close to the lower‐hybrid frequency in 12 magnetotail reconnection electron diffusion region (EDR) events with guide field levels of near‐zero to 30%. In about half of the events, the wave vector has a small component along the current sheet normal, consistent with known lower‐hybrid drift wave properties, but the perpendicular magnetic field fluctuations can be comparable or greater than the parallel component, a feature unique to the waves inside and adjacent to EDRs. Another new wave property is that the wave vector has a significant component along the current sheet normal in some events and completely along the normal for one event. In 1/4 of the events, the ∇·Pe $\nabla \cdot {\boldsymbol{P}}_{e}$ term has a significant contribution to the wave electric field, possibly a feature of lower‐hybrid waves more likely to exist in the diffusion region than further away from the X‐line. Electron temperature variations are correlated with the wave potential, due to wave electric field acceleration and crossings at the corrugated separatrix region with different amounts of mixing between reconnection inflowing and outflowing populations. The latter also leads to the anti‐correlation between parallel and perpendicular temperature components. Using four‐spacecraft measurements, the magnetic field line twisting is demonstrated by the correlated fluctuations in ∇×VE×B|| ${\left(\nabla \times {\boldsymbol{V}}_{E\times B}\right)}_{\vert \vert }$ and (∇×boldB)|| ${(\nabla \times \mathbf{B})}_{\vert \vert }$. The lower‐hybrid wave in the EDR of weak guide field reconnection may be generated near separatrices and penetrate to the mid‐plane or locally generated, and the latter possibility is beyond the prediction of previous reconnection simulations.

show abstract

“…A finite β shall reduce the maximum growth rate by a factor of ( ) 1 2 i 1 2 b + - (Davidson et al 1977). In recent Magnetospheric Multiscale (MMS) observations, the generation of LHWs through LHDI is investigated in the vicinity of the exhaust and diffusion regions at Earth's magnetopause (Graham et al 2017;Zhou et al 2018;Graham et al 2019;Tang et al 2020;Ren et al 2022;Wang et al 2022). LHWs are frequently found in sharp density gradients and the low-β side of the reconnection layers (Pritchett et al 2012;Graham et al 2019;Ren et al 2022Ren et al , 2023.…”

Section: Introductionmentioning

confidence: 99%

The Wave Growth, Saturation, and Electron Heating of Lower Hybrid Waves in the Magnetic Reconnection Exhaust

Ren,

Dai,

Wang

et al. 2023

ApJ

Self Cite

View full text Add to dashboard Cite

Lower hybrid waves are commonly observed in magnetic reconnection. Based on in situ measurements and the application of an extended quasi-linear model, we investigate the occurrence, saturation, and electron heating of lower hybrid waves in the region of magnetopause reconnection outflows. Lower hybrid waves are statistically favored when the density gradient length scale (L n ) normalized by the ion gyroradius (ρ i ) is small. The occurrence of lower hybrid waves is significantly higher in the regime of L n /ρ i < 1 and plasma beta β < 1. These features of wave occurrence are consistent with the linear theory of the wave growth rate. Evidence indicates that the saturation level and the parallel electron heating of waves both increase as the normalized gradient scale L n /ρ i decreases. The parallel electron temperature increases ∼30%–70% as L n /ρ i < 1. We show that the observation of saturation and electron heating is consistent with an extended quasi-linear model. In this scenario, lower hybrid waves are driven by density gradients and then quickly saturate in tens of ion gyroperiods. The parallel electron heating from lower hybrid waves is achieved through Landau damping before the nonlinear saturation. Our results provide comprehensive evidence for an end-to-end process of electron heating through lower hybrid waves in reconnection exhausts. L n /ρ i is the key parameter that determines the extent of the wave growth, saturation energy, and electron heating in this wave–particle interaction process.

show abstract

Lower Hybrid Waves at the Magnetosheath Separatrix Region

Cited by 8 publications

References 50 publications

Electron acceleration driven by the lower-hybrid-drift instability

Electron acceleration driven by the lower-hybrid-drift instability

Lower‐Hybrid Wave Structures and Interactions With Electrons Observed in Magnetotail Reconnection Diffusion Regions

The Wave Growth, Saturation, and Electron Heating of Lower Hybrid Waves in the Magnetic Reconnection Exhaust

Contact Info

Product

Resources

About