Rippled Quasiperpendicular Shock Observed by the Magnetospheric Multiscale Spacecraft

Johlander, Andreas; Schwartz, Steven J.; Vaivads, A.; Khotyaintsev, Yuri; Gingell, Imogen; Peng, Ivy Bo; Markidis, Stefano; Lindqvist, Per‐Arne; Ergun, R. E.; Marklund, Göran; Plaschke, Ferdinand; Magnes, W.; Strangeway, R. J.; Russell, C. T.; Wei, H. Y.; Torbert, R. B.; Paterson, W. R.; Gershman, D. J.; Dorelli, J.; Avanov, L. A.; Lavraud, B.; Saito, Y.; Giles, B. L.; Pollock, C. J.; Burch, J. L.

doi:10.1103/physrevlett.117.165101

Cited by 115 publications

(132 citation statements)

References 27 publications

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“…Individual normals deviated from the timing analysis normal by up to 30°. This is presumably a typical feature of high Mach number shocks, in agreement with several past modeling studies of shocks (Burgess, ; Burgess & Scholer, ; Lowe & Burgess, ; Ofman & Gedalin, , ; Winske & Quest, ) as well as observations reported by (Johlander et al, ). In particular, Ofman and Gedalin (, ) discussed the deviation of the shock normal due to rippling, based on their 2‐D hybrid simulation study.…”

Section: Discussionsupporting

confidence: 91%

“…To conclude, we present the results of a comparative study of two quasi‐perpendicular collisionless shocks in the solar wind, with low (IP shock) and high (bow shock) Mach number: The cross‐shock NIF potential from electric field measurements is 24–28 V for the IP shock (with 41–42 V from the electron proxies), and 290–440 V for the bow shock (with 240–260 V from the electron proxies). The ion proxies cannot be used for high Mach number shocks because the ion moments are spoiled by reflected ions before and during the ramp. The low Mach number IP shock surface was almost planar on the scale of the MMS spacecraft configuration as well as on the scale of the MMS and ARTEMIS separation distance (~20 R E ). The high Mach number bow shock surface was rippled on the scale of the MMS spacecraft configuration, in agreement with the results of Burgess (), Burgess and Scholer (), Lowe and Burgess (), Ofman and Gedalin (, ), and Winske and Quest () and the observations of Johlander et al (). …”

Section: Discussionmentioning

confidence: 99%

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Cross‐Shock Potential in Rippled Versus Planar Quasi‐Perpendicular Shocks Observed by MMS

Hanson

Agapitov

Mozer

et al. 2019

Geophysical Research Letters

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The unprecedented detail of measurements by the four Magnetospheric Multiscale (MMS) spacecraft enable deeper investigation of quasi‐perpendicular collisionless shocks. We compare shock normals, planarities, and Normal Incidence Frame cross‐shock potentials determined from electric field measurements and proxies, for a subcritical interplanetary shock and a supercritical bow shock. The subcritical shock's cross‐shock potential was 26±6 V. The shock scale was 33 km, too short to allow comparison with proxies from ion moments. Proxies from electron moments provided potential estimates of 40±5 V. Shock normals from magnetic field minimum variance analysis were nearly identical, indicating a planar front. The supercritical shock's cross‐shock potential was estimated to be from 290 to 440 V from the different spacecraft measurements, with shock scale 120 km. Reflected ions contaminated the ion‐based proxies upstream, whereas electron‐based proxies yielded reasonable estimates of 250±50 V. Shock normals from electric field maximum variance analysis differed, indicating a rippled front.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Cross‐Shock Potential in Rippled Versus Planar Quasi‐Perpendicular Shocks Observed by MMS

Hanson

Agapitov

Mozer

et al. 2019

Geophysical Research Letters

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“…But also during rather stable conditions, it can be both nonuniform and nonstationary. For example, ripples can propagate on the surface and it has been suggested that the shock can exhibit cyclical reformation (e.g., Auer et al, ; Eastwood et al, ; Johlander et al, ). As shown in section 3, the events included in our database are observed Earthward of the nominal subsolar position of the bow shock, indicating that they correspond to rather elevated upstream solar wind conditions.…”

Section: Summary and Discussionmentioning

confidence: 99%

Bow Shock Generator Current Systems: MMS Observations of Possible Current Closure

et al. 2018

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We use data from the first two dayside seasons of the Magnetospheric Multiscale (MMS) mission to study current systems associated with quasi‐perpendicular bow shocks of generator type. We have analyzed 154 MMS bow shock crossings near the equatorial plane. We compute the current density during the crossings and conclude that the component perpendicular to the shock normal (J⊥) is consistent with a pileup of the interplanetary magnetic field (IMF) inside the magnetosheath. For predominantly southward IMF, we observe a component Jn parallel (antiparallel) to the normal for GSM Y > 0 (<0), and oppositely directed for northward IMF. This indicates current closure across the equatorial magnetosheath, and it is observed for IMF clock angles near 0∘ and 180∘. To our knowledge, these are the first observational evidence for bow shock current closure across the magnetosheath. Since we observe no clear signatures of |J⊥| decreasing toward large |Y| we suggest that the main region of current closure is further tailward, outside MMS probing region. For IMF clock angles near 90∘, we find indications of the current system being tilted toward the north‐south direction, obtaining a significant Jz component, and we suggest that the current closes off the equatorial plane at higher latitudes where the spacecraft are not probing. The observations are complicated for several reasons. For example, variations in the solar wind and the magnetospheric currents and loads affect the closure, and Jn is distributed over large regions, making it difficult to resolve inside the magnetosheath proper.

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“…This is especially important in regions for which kinetic plasma processes are significant, and associated nongyrotropic particle populations are common. The MMS mission targets several of these regions, such as the bow shock (Johlander et al, ) or the diffusion regions of magnetic reconnection sites (Burch, Torbert, et al, ). In these regions, characterization of the full ion or electron phase space is critical to understanding of microphysics processes.…”

Section: Introductionmentioning

confidence: 99%

Production of Negative Hydrogen Ions Within the MMS Fast Plasma Investigation Due to Solar Wind Bombardment

et al. 2018

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The particle data delivered by the Fast Plasma Investigation instrument aboard National Aeronautics and Space Administration's Magnetospheric Multiscale (MMS) mission allow for exceptionally high‐resolution examination of the electron and ion phase space in the near‐Earth plasma environment. It is necessary to identify populations which originate from instrumental effects. Using Fast Plasma Investigation's Dual Electron Spectrometers, we isolate a high‐energy (approximately kiloelectron volt) beam, present while the spacecraft are in the solar wind, which exhibits an azimuthal drift with period associated with the spacecraft spin. We show that this population is consistent with negative hydrogen ions H− generated by a double charge exchange interaction between the incident solar wind H+ ions and the metallic surfaces within the instrument. This interaction is likely to occur at the deflector plates close to the instrument aperture. The H− density is shown to be approximately 0.2–0.4% of the solar wind ion density, and the energy of the negative ion population is shown to be 70% of the incident solar wind energy. These negative ions may introduce errors in electron velocity moments on the order of 0.2–0.4% of the solar wind velocity and significantly higher errors in the electron temperature.

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Rippled Quasiperpendicular Shock Observed by the Magnetospheric Multiscale Spacecraft

Cited by 115 publications

References 27 publications

Cross‐Shock Potential in Rippled Versus Planar Quasi‐Perpendicular Shocks Observed by MMS

Cross‐Shock Potential in Rippled Versus Planar Quasi‐Perpendicular Shocks Observed by MMS

Bow Shock Generator Current Systems: MMS Observations of Possible Current Closure

Production of Negative Hydrogen Ions Within the MMS Fast Plasma Investigation Due to Solar Wind Bombardment

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