Shock Drift Acceleration of Ions in an Interplanetary Shock Observed by MMS

Hanson, E.; Agapitov, Oleksiy; Vasko, I. Y.; Mozer, F. S.; Krasnoselskikh, V.; Bale, S. D.; Avanov, L. A.; Khotyaintsev, Yuri V.; Giles, B. L.

doi:10.3847/2041-8213/ab7761

Cited by 10 publications

(7 citation statements)

References 45 publications

(55 reference statements)

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“…For this reason, this section describes MMS observations of MMs that were observed directly downstream of an IP shock on 24 October 2017. This is shown in Figure 10, and although IP shocks have been reported (Cohen et al, 2019;Hanson et al, 2020), this event is likely to be the earliest known IP shock measured by MMS. Panels (a-d) show |B|, n e , and V i , and ellipticity.…”

Section: Mirror Mode Storm Downstream Of An Ip Shock By Mmsmentioning

confidence: 79%

Mirror Mode Storms Observed by Solar Orbiter

et al. 2022

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Mirror modes are ubiquitous in space plasma and grow from pressure anisotropy. Together with other instabilities, they play a fundamental role in constraining the free energy contained in the plasma. This study focuses on mirror modes observed in the solar wind by Solar Orbiter for heliocentric distances between 0.5 and 1 AU. Typically, mirror modes have timescales from several to tens of seconds and are considered quasi-MHD structures. In the solar wind, they also generally appear as isolated structures. However, in certain conditions, prolonged and bursty trains of higher frequency mirror modes are measured, which have been labeled previously as mirror mode storms. At present, only a handful of existing studies have focused on mirror mode storms, meaning that many open questions remain. In this study, Solar Orbiter has been used to investigate several key aspects of mirror mode storms: their dependence on heliocentric distance, association with local plasma properties, temporal/spatial scale, amplitude, and connections with larger-scale solar wind transients. The main results are that mirror mode storms often approach local ion scales and can no longer be treated as quasi-MHD, thus breaking the commonly used long-wavelength assumption. They are typically observed close to current sheets and downstream of interplanetary shocks. The events were observed during slow solar wind speeds and there was a tendency for higher occurrence closer to the Sun. The occurrence is low, so they do not play a fundamental role in regulating ambient solar wind but may play a larger role inside transients.

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Section: Mirror Mode Storm Downstream Of An Ip Shock By Mmsmentioning

confidence: 79%

Mirror Mode Storms Observed by Solar Orbiter

et al. 2022

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“…We note that ion holes in the auroral region were shown to carry negligible (if any) potential drops [94]. In any case, we expect the leading contribution to the cross-shock potential drop to be from the macroscopic electric field (on scales of about ion inertial length) capable of coherently reflecting incoming protons [e.g., 113,114,115].…”

Section: Interpretation and Discussionmentioning

confidence: 98%

Electrostatic solitary waves in the Earth's bow shock: nature, properties, lifetimes and origin

Wang,

Vasko,

Mozer

et al. 2021

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In this paper we present a comprehensive statistical analysis of more than two thousand bipolar electrostatic solitary waves (ESW) collected from ten quasi-perpendicular Earth's bow shock crossings by Magnetospheric Multiscale spacecraft. We developed and implemented a correction procedure for reconstruction of actual electric fields, velocities, and other properties of ESW from measurements, whose spatial scales are typically comparable with or even several times smaller than spatial distance between axial and spin plane voltage-sensitive probes. We also determined the optimal ratio between frequency response factors of axial and spin plane antennas used for interferometry analysis of ESW. We found that more than 95% of the ESW in the Earth's bow shock are of negative polarity and present an in depth analysis of properties of these ESW. They have spatial scales of about 10-100 meters, amplitudes typically below a few Volts, and velocities from a few tens to a few hundreds km/s in spacecraft and plasma rest frames. The spatial scales of ESW are distinctly correlated with local Debye length λ D , being typically within a range of λ D to 10λ D . Their amplitudes are typically below 0.1 of local electron temperature, and their velocities are on the order of local ion-acoustic speed. We also observed large-amplitude ESW with amplitudes of 5-30 V or 0.1-0.3 of local electron temperature with occurrence rate of a few percent. The ESW have electric fields generally oblique to local magnetic field and propagate highly oblique to shock normal N; more than 80% of ESW propagate within 30 • of the shock plane. In the shock plane, ESW typically propagate within a few tens of degrees of local magnetic field projection B LM onto the shock plane and preferentially opposite to N × B LM . We argue that the ESW of negative polarity are ion phase space holes, which are solitary waves produced in a nonlinear stage of various ion-streaming instabilities. We estimated lifetimes of the ion holes to be 10-100 ms, or 1-10 km in terms of spatial distance. We speculate that the ion holes are likely produced by the ion-ion streaming instability, because amplitudes of the ion holes fall below the threshold expected for the saturation of this instability at typical densities of ion beams in the Earth's bow shock; this instability can also explain highly oblique propagation of the ion holes to shock normal.

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“…We note that ion holes in the auroral region were shown to carry negligible (if any) potential drops (McFadden et al., 2003). In any case, we expect the leading contribution to the cross‐shock potential drop to be from the macroscopic electric field (on scales of about ion inertial length) capable of coherently reflecting incoming protons (e.g., I. J. Cohen et al., 2019; Dimmock et al., 2012; Hanson et al., 2020). Fourth, the ion holes have electric fields oriented typically oblique to local magnetic field, implying that these solitary waves can in principle efficiently pitch‐angle scatter and thermalize electrons in the Earth's bow shock (Gedalin, 2020; Vasko, Krasnoselskikh, et al., 2018; Vasko, Mozer, et al., 2018).…”

Section: Interpretation and Discussionmentioning

confidence: 99%