Negative Potential Solitary Structures in the Magnetosheath With Large Parallel Width

Holmes, J. C.; Ergun, R. E.; Newman, D. L.; Wilder, F. D.; Sturner, A. P.; Goodrich, K.; Torbert, R. B.; Giles, B. L.; Strangeway, R. J.; Burch, J. L.

doi:10.1002/2017ja024890

Cited by 18 publications

(25 citation statements)

References 49 publications

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“…This corresponds to a peak-to-peak electric field of E ≈ 90 mV/m (potential φ and space x are, respectively, unnormalized by k B T h /e = 9.9 × 10 5 mV and λ 0 = ε 0 k B T h /n c,0 e 2 = 74 m), which is in agreement with the peak-to-peak electric filed of ∼ 100 mV/m observed in the BEN [17]. Similarly, the parameters of the magnetosphere plasma observed by the MMS mission [21,22] (T b ∼ 1 eV, T h ∼ 1 keV, n b ∼ 0.2 cm −3 , and n h ∼ 30 cm −3 ) yield a peak-to-peak electric field of E ≈ 160 mV/m (k B T h /e = 10 6 mV and λ 0 = 43 m), which is roughly close to the large-amplitude, parallel electric fields of ∼ 100 mV/m measured at the magnetic reconnection region of the Earth's magnetopause [21].…”

Section: Discussionsupporting

confidence: 78%

Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

Danehkar

2018

Plasma Phys. Control. Fusion

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Suprathermal electrons and inertial drifting electrons, so called electron beam, are crucial to the nonlinear dynamics of electrostatic solitary waves observed in several astrophysical plasmas. In this paper, the propagation of electron-acoustic solitary waves is investigated in a collisionless, unmagnetized plasma consisting of cool inertial background electrons, hot suprathermal electrons (modeled by a κ-type distribution), and stationary ions. The plasma is penetrated by a cool electron beam component. A linear dispersion relation is derived to describe small-amplitude wave structures that shows a weak dependence of the phase speed on the electron beam velocity and density. A (Sagdeev-type) pseudopotential approach is employed to obtain the existence domain of large-amplitude solitary waves, and investigate how their nonlinear structures depend on the kinematic and physical properties of the electron beam and the suprathermality (described by κ) of the hot electrons. The results indicate that the electron beam can largely alter the electron-acoustic solitary waves, but can only produce negative polarity solitary waves in this model. While the electron beam co-propagates with the solitary waves, the soliton existence domain (Mach number range) becomes narrower (nearly down to nil) with increasing the beam speed and the beam-to-hot electron temperature ratio, and decreasing the beam-tocool electron density ratio in high suprathermality (low κ). It is found that the electric potential amplitude largely declines with increasing the beam speed and the beam-tocool electron density ratio for co-propagating solitary waves, but is slightly decreased by raising the beam-to-hot electron temperature ratio.

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Section: Discussionsupporting

confidence: 78%

Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

Danehkar

2018

Plasma Phys. Control. Fusion

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“…In near‐Earth space, such data enabled observations of kinetic‐scale electric field structures, such as electron phase space holes and plasma double layers (e.g., Cattell et al, 2002; Ergun et al, 2001, 2009; Franz et al, 1998; Fu et al, 2020; Holmes et al, 2018; Li et al, 2015; Malaspina et al, 2014; Matsumoto et al, 1994; Mozer et al, 2013; Pickett et al, 2003). These structures characteristically feature strong electric fields parallel to the background magnetic field, and they appear in kinetically unstable plasmas (e.g., Hutchinson, 2017; Schamel, 2012, and references therein), often in association with magnetic field‐aligned currents (Ergun et al, 2001; Mozer et al, 2014) or near the interface between two disparate plasma populations as they homogenize (Holmes et al, 2018; Malaspina et al, 2014; Pickett et al, 2004). In near‐Earth space, kinetic‐scale electric field structures have been identified in virtually every region where significant wave‐particle energy transfer occurs and instrumentation capable of observing them is present, including the auroral region (Ergun et al, 2001), plasma sheet (Ergun et al, 2009; Matsumoto et al, 1994), radiation belts (Malaspina et al, 2014; Mozer et al, 2013), magnetosheath (Cattell et al, 2002; Pickett et al, 2003), and bow shock (Goodrich et al, 2018; Li et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Plasma Double Layers at the Boundary Between Venus and the Solar Wind

Malaspina

Goodrich

Livi

et al. 2020

Geophysical Research Letters

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The solar wind is slowed, deflected, and heated as it encounters Venus's induced magnetosphere. The importance of kinetic plasma processes to these interactions has not been examined in detail, due to a lack of constraining observations. In this study, kinetic-scale electric field structures are identified in the Venusian magnetosheath, including plasma double layers. The double layers may be driven by currents or mixing of inhomogeneous plasmas near the edge of the magnetosheath. Estimated double-layer spatial scales are consistent with those reported at Earth. Estimated potential drops are similar to electron temperature gradients across the bow shock. Many double layers are found in few high cadence data captures, suggesting that their amplitudes are high relative to other magnetosheath plasma waves. These are the first direct observations of plasma double layers beyond near-Earth space, supporting the idea that kinetic plasma processes are active in many space plasma environments. Plain Language Summary Venus has no internally generated magnetic field, yet electric currents running through its ionized upper atmosphere create magnetic fields that push back against the flow of the solar wind. These induced fields cause the solar wind to slow and heat as the flow is deflected around Venus. This work reports observations of very small plasma structures that accelerate particles, identifiable by their characteristic electric field signatures, at the boundary where the solar wind starts to be deflected. These small plasma structures observed at Venus have been studied in near-Earth space for decades but have never before been found near another planet. These structures are known to be important to the physics of strong electrical currents in space plasmas and the blending of dissimilar plasmas. Their identification at Venus is a strong demonstration that these small plasma structures are a universal plasma phenomena, at work in many plasma environments.

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“…Simultaneous, in situ observations from multiple spacecraft are an excellent tool for pursuing a detailed understanding of three‐dimensional phase‐space hole dynamics (Pickett et al, ). Previous measurements of solitary waves on two spacecraft (Holmes et al, ; Norgren et al, ; Pickett et al, ) show improvement in determining individual structure properties such as perpendicular distance to the structure center. More points of reference reduce uncertainty in which signatures correlate with one another, particularly for closely spaced solitary waves.…”

Section: Introductionmentioning

confidence: 99%

Electron Phase‐Space Holes in Three Dimensions: Multispacecraft Observations by Magnetospheric Multiscale

et al. 2018

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Electron phase‐space holes are kinetic plasma structures commonly observed in space plasmas on Debye length scales. Near the Earth's duskside flank at 10 Earth radii, a series of 32 electron holes (EHs) are detected within a 1‐s window on all four Magnetospheric Multiscale spacecraft. The spacecraft separation of <7 km is similar to the expected EH size in this region. Length, width, amplitude, and relative positions are determined for individual EHs using a cylindrically symmetric model fit to Magnetospheric Multiscale E field measurements. The model shows good agreement with observed E fields far from the EH center. Deviations in E⊥ from the model are present near the center, indicating observed EHs have complex, sometimes irregular, internal structure. Perturbation magnetic fields δB modeled assuming an E × B0 electron current reproduce the measured parallel perturbation in most cases, although there is a systematic variation due to geometric and finite gyroradius effects. Many EHs in this event have large amplitude for their size, reaching the theoretical lower limit in length parallel to the background magnetic field, which requires the electron phase‐space density to approach 0 in the center. It is possible that EHs of this type have recently formed, eventually weakening or becoming longer over time. This study provides the most detailed measurements of EHs to date. Their derived properties are largely in agreement with expectations from previous research. It remains unclear whether the few notable differences are due to rapid time evolution or are specific to the local environment.

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Negative Potential Solitary Structures in the Magnetosheath With Large Parallel Width

Cited by 18 publications

References 49 publications

Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

Plasma Double Layers at the Boundary Between Venus and the Solar Wind

Electron Phase‐Space Holes in Three Dimensions: Multispacecraft Observations by Magnetospheric Multiscale

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