First Observation of Lower Hybrid Drift Waves at the Edge of the Current Sheet in the Martian Magnetotail

Abstract

Lower hybrid drift waves are commonly observed at plasma boundaries, playing an important role in plasma dynamics. Such waves have been widely investigated in the terrestrial magnetosphere but have never been reported in other planetary environments. Here, using the measurements from the Mars Atmosphere and Volatile EvolutioN mission, we present the first observation of electromagnetic lower hybrid drift waves at the edge of the current sheet on the dusk side of the Martian magnetotail, which should be locally excited rather than propagated from other regions. These plasma waves are associated with significant density gradients and magnetic field gradients. Based on the measured local plasma parameters and the sufficient condition for lower hybrid drift instability to be excited, we find that the proton density gradient is sharp enough to excite the lower hybrid drift instability. The analysis of the existence condition for lower hybrid drift instability indicates that these lower hybrid drift waves at the edge of the current sheet are generated through lower hybrid drift instability. The above results can improve our understanding of Mars’ magnetospheric dynamics.

Retracted: New Types of Electron Pitch Angle Distributions on Mars: Funnel and Skirt Distributions

“…The field‐aligned beam and loss cone, showing a local maximum flux at $$0{}^{\circ}$$ and a local minimum flux at $$180{}^{\circ}$$, has been reported in studying backscattered electrons (Brain et al., 2007). The isotropic PADs, showing electron pitch angles uniformly from $$0{}^{\circ}$$ to $$180{}^{\circ}$$, has been frequently observed inside current sheet (e.g., Guo, Liu, et al., 2022). The two‐sided conic, also termed bidirectional electron conic or butterfly PADs, showing electron pitch angles around $$45{}^{\circ}$$ and $$135{}^{\circ}$$, has been observed on the nightside as well as near strong crustal magnetic anomalies (e.g., Cao et al., 2020; Ulusen et al., 2011).…”

Observation of Interchange Reconnection on Mars

“…Thus, reconnection is happening in this current sheet. It is noted that the power spectral density of the parallel component of magnetic field is enhanced around the lower hybrid frequency (not shown here), which indicates the existence of lower hybrid drift waves (e.g., Guo et al 2022). Such lower hybrid drift waves are frequently observed during the reconnection process (e.g., Zhou et al 2014;Chen et al 2022).…”

Betatron Acceleration of Suprathermal Electrons Upstream of the Martian Bow Shock

“…In other words, we have quantitatively confirmed the betatron acceleration process in these two events, and the results of betatron accelerated modeling are consistent with MAVEN's observations. Additionally, it is also worth noting that both of the betatron factors are slightly below the ratios of the postacceleration to the pre-acceleration magnetic fields, which may be due to the existence of other non-adiabatic processes during betatron acceleration (Fu et al 2019a(Fu et al , 2020cShane et al 2019;Grigorenko et al 2020;Guo et al 2022Guo et al , 2021bRen et al 2021), or the fact that the betatron acceleration process has evolved for some time before being observed by spacecraft.…”