Interplay between Kelvin–Helmholtz and lower-hybrid drift instabilities

Dargent, Jérémy; Lavorenti, Federico; Califano, Francesco; Henri, Pierre; Pucci, Francesco; Cerri, Silvio Sergio

doi:10.1017/s0022377819000758

Cited by 9 publications

(5 citation statements)

References 85 publications

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“…Recent studies have shown the interplay between the LHDI and the KHI from 2D fully kinetic simulations using parameters typical for the magnetopause of Mercury. 51 Depending on the density gradient and velocity shear across the boundary, the LHDI and the KHI can compete for their respective growth. If the density gradient is strong enough, the LHDI disturbs the structure of the shear layer and can even suppress the onset and evolution of the KHI.…”

Section: Lower Hybrid Wavesmentioning

confidence: 99%

Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF

et al. 2022

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In this study, we present the first observations from the Magnetospheric Multiscale (MMS) mission of the Kelvin-Helmholtz instability (KHI) at the dusk-flank magnetopause during southward interplanetary magnetic field conditions on September 23, 2017. The instability criterion for the KHI was fulfilled for the plasma parameters observed throughout the event. An analysis of the boundary normal vectors based on the application of the timing method onto the magnetic field and the electron density data and the minimum directional derivative method onto the magnetic field data shows signatures of surface waves in the plane parallel to the velocity shear. A comparison to 2D fully kinetic simulations demonstrates reasonable consistencies with the formation of surface waves generated by the KH instability, as well as the structures of rolled-up KH waves. The observations further indicated low density faster than sheath plasma as an indicator of rolled-up vortices, which is also consistent with the simulations. All of these results show that the observed waves and vortices are most likely generated by the KH instability. High-time resolution MMS measurements further demonstrate kinetic-scale electric field fluctuations on the low-density side of the edges of surface waves. Detailed comparisons with the simulations suggest that the observed fluctuations are generated by the lower-hybrid drift instability excited by the density gradient at the edges of these surface waves. These secondary effects can lead to a flattening of the edge layers, indicating the connection between kinetic and larger scales within the KH waves and vortices.

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Section: Lower Hybrid Wavesmentioning

confidence: 99%

Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF

et al. 2022

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“…In collisionless space plasmas, plasma mixing across the magnetic field lines occurs at small-scale structures, caused by secondary instabilities excited in the rolled-up vortex of KHI, i.e., at a welldeveloped KHI. To understand the momentum and mass transport mechanisms across the velocity-sheared boundary, high-resolution kinetic simulations of KHI have been conducted (Matsumoto and Seki, 2010;Dargent et al, 2019). Some of the previous studies have identified the importance of including electron inertial effects when assessing mass transport mechanisms across the boundaries.…”

Section: Discussionmentioning

confidence: 99%

“…The change in the initial condition largely alters the time evolution of KHI, even in the small and moderate density gradient cases. For example, the usage of the proposed entropy-based model based on the observations will be important for understanding the interplay between KHI and the lower-hybrid drift instability in plasma mixing (Dargent et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Characteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability

Seki,

Matsumoto,

Terada

et al. 2024

Front. Astron. Space Sci.

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Boundaries between space plasmas occur in numerous contexts and scales, from astrophysical jets to planetary magnetospheres. Mass and momentum transport across boundaries poses a fundamental problem in magnetospheric physics. Kelvin–Helmholtz instability (KHI) is a promising mechanism to facilitate transport. Although previous studies have suggested KHI occurrence in various space plasmas, theory predicts that compressibility prevents KHI excitation at boundaries with large density gradients because of previously considered boundary structures where density varies with velocity. Based on the observations of a large density gradient boundary by MAVEN at Mars, where we can observe an extreme case, in this study, we show that it is the entropy, instead of the previously considered density, that varies with the velocity in the real velocity-sheared boundary. The entropy-based boundary structure places the velocity shear in a lower-density region than the traditional density-based structure and weakens the compressibility effect. This new boundary structure thus enables KHI excitation even at large density gradient boundaries, such as at the ionopause of unmagnetized planets and the plasmapause of magnetized planets. The result suggests the ubiquitous occurrence of KHI in the plasma universe and emphasizes its important role in planetary cold plasma escape from unmagnetized planets.

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“…In this context, other instabilities, that can build on the free energy available at the magnetopause and compete with the KHI in an asymmetric velocity shear, shall leave a significant electric field fingerprints to be observed by MEFISTO. This is for instance the case of the lower-hybrid drift instability that might build on the strong density gradients at the Hermean magnetopause and reduce or even suppress the development of the KHI (Dargent et al 2019).…”

Section: Foreshock Waves and Structuresmentioning

confidence: 99%

The MEFISTO and WPT Electric Field Sensors of the Plasma Wave Investigation on the BepiColombo Mio Spacecraft

et al. 2020

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This paper describes the design of MEFISTO (Mercury Electric Field In-Situ Tool) and WPT (Wire Probe Antenna) electric field sensors for Plasma Wave Investigation (PWI) on the BepiColombo Mio spacecraft (Mercury Magnetospheric Orbiter, MMO). The two sensors will enable the first observations of electric fields, plasma waves and radio waves in and around the Hermean magnetosphere and exosphere. MEFISTO and WPT are dipole antennas with 31.6 m tip-to-tip length. Each antenna element has a spherical probe at each end of the wire (15 m length). They are extended orthogonally in the spin plane of the spacecraft and enable measurements of the electric field in the frequency range of DC to 10 MHz by the connection to two sets of receivers, EWO for a lower frequency range and SORBET for higher frequencies. In the initial operations after the launch (20 Oct. 2018), we succeeded to confirm the health of both antennas and to release the launch lock of the WPT. After Mercury orbit insertion planned at the end of 2025, both sensors will be fully deployed and activate full operations of the PWI electric field measurements.

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Interplay between Kelvin–Helmholtz and lower-hybrid drift instabilities

Cited by 9 publications

References 85 publications

Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF

Multi-scale observations of the magnetopause Kelvin–Helmholtz waves during southward IMF

Characteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability

The MEFISTO and WPT Electric Field Sensors of the Plasma Wave Investigation on the BepiColombo Mio Spacecraft

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