The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

R B Torbert - One of the best experts on this subject based on the ideXlab platform.

B L Giles - One of the best experts on this subject based on the ideXlab platform.

  • Electron vorticity indicative of the Electron Diffusion region of magnetic reconnection
    Geophysical Research Letters, 2019
    Co-Authors: K J Hwang, J. L. Burch, B L Giles, C J Pollock, E Choi, Kyunghwan Dokgo, D G Sibeck, M L Goldstein, W R Paterson, Huimin Fu
    Abstract:

    Author(s): Hwang, K-J; Choi, E; Dokgo, K; Burch, JL; Sibeck, DG; Giles, BL; Goldstein, ML; Paterson, WR; Pollock, CJ; Shi, QQ; Fu, H; Hasegawa, H; Gershman, DJ; Khotyaintsev, Y; Torbert, RB; Ergun, RE; Dorelli, JC; Avanov, L; Russell, CT; Strangeway, RJ | Abstract: While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced Electron vorticity in the vicinity of the Electron Diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying Electron jets in the direction along the Electron meandering motion or out-of-plane direction, agyrotropic Electron distribution functions, and dissipative signatures. At the edge of the Electron jets, the Electron vorticity increased with magnitudes greater than the Electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that Electron vorticity can act as a proxy for delineating the Electron Diffusion region of magnetic reconnection.

  • reconstruction of the Electron Diffusion region of magnetotail reconnection seen by the mms spacecraft on 11 july 2017
    Journal of Geophysical Research, 2019
    Co-Authors: H Hasegawa, K J Genestreti, R B Torbert, T. D. Phan, K J Hwang, R E Denton, R Nakamura, T K M Nakamura, J L Burch, B L Giles
    Abstract:

    We present results from the reconstruction of the Electron Diffusion region of magnetotail reconnection observed by the Magnetospheric Multiscale (MMS) spacecraft on 11 July 2017. In the event, the ...

  • structure and dissipation characteristics of an Electron Diffusion region observed by mms during a rapid normal incidence magnetopause crossing
    Journal of Geophysical Research, 2017
    Co-Authors: R B Torbert, B L Giles, M R Argall, A C Rager, J L Burch, C J Farrugia, T G Forbes, J Dorelli
    Abstract:

    On 22 October 2016, the Magnetospheric Multiscale (MMS) spacecraft encountered the Electron Diffusion region (EDR) when the magnetosheath field was southward, and there were signatures of fast reco ...

  • mms observations of whistler waves in Electron Diffusion region
    Geophysical Research Letters, 2017
    Co-Authors: H S Fu, Yuri V. Khotyaintsev, Shiyong Huang, Daniel B Graham, Tieyan Wang, Zhengzhang Chen, F Z Peng, M Andre, C T Russell, B L Giles
    Abstract:

    Whistler waves that can produce anomalous resistivity by affecting Electrons' motion have been suggested as one of the mechanisms responsible for magnetic reconnection in the Electron Diffusion reg ...

  • magnetospheric multiscale mission observations of the outer Electron Diffusion region
    Geophysical Research Letters, 2017
    Co-Authors: Yuri V. Khotyaintsev, R E Ergun, L J Chen, E Choi, D G Sibeck, Kyoungjoo Hwang, B L Giles
    Abstract:

    This paper presents Magnetospheric Multiscale mission (MMS) observations of the exhaust region in the vicinity of the central reconnection site in Earth's magnetopause current sheet. High-time-resolution measurements of field and particle distributions enable us to explore the fine structure of the Diffusion region near the X line. Ions are decoupled from the magnetic field throughout the entire current sheet crossing. Electron jets flow downstream from the X line at speeds greater than the E × B drift velocity. At/around the magnetospheric separatrix, large-amplitude electric fields containing field-aligned components accelerate Electrons along the magnetic field toward the X line. Near the neutral sheet, crescent-shaped Electron distributions appear coincident with (1) an out-of-plane electric field whose polarity is opposite to that of the reconnection electric field and (2) the energy transfer from bulk kinetic to field energy. The observations indicate that MMS passed through the edge of an elongated Electron Diffusion region (EDR) or the outer EDR in the exhaust region.

F. S. Mozer - One of the best experts on this subject based on the ideXlab platform.

  • evidence for an elongated 60 ion skin depths Electron Diffusion region during fast magnetic reconnection
    Physical Review Letters, 2007
    Co-Authors: T. D. Phan, F. S. Mozer, J F Drake, M A Shay, J P Eastwood
    Abstract:

    Observations of an extremely elongated Electron Diffusion region occurring during fast reconnection are presented. Cluster spacecraft in situ observations of an expanding reconnection exhaust reveal a broad current layer ({approx}10 ion skin depths thick) supporting the reversal of the reconnecting magnetic field together with an intense current embedded at the center that is due to a super-Alfvenic Electron outflow jet with transverse scale of {approx}9 Electron skin depths. The Electron jet extends at least 60 ion skin depths downstream from the X-line.

  • New features of Electron Diffusion regions observed at subsolar magnetic field reconnection sites
    Geophysical Research Letters, 2005
    Co-Authors: F. S. Mozer, Stuart D. Bale, J. P. Mcfadden, Roy Torbert
    Abstract:

    [1] Nineteen Electron Diffusion regions at magnetic field reconnection sites have been found in one hour of Cluster satellite data near the subsolar magnetopause. Investigations on previously unachieved spatial and temporal scales show the following for the first time: direct conversion of magnetic energy to Electron energy (The resulting accelerated Electrons, their field-aligned currents, and their post-acceleration fate were measured); the spatial dimensions of the large electric fields in the Electron Diffusion regions have an average thickness of 0.3 times the Electron skin depth, in agreement with theory; and these Electron Diffusion regions were topological boundaries between open and closed magnetic field geometries that contained different plasma and magnetic field line flows. The Electron Diffusion regions were located at the magnetospheric separatrix where the magnetic field was large and the Electron beta was less than one.

  • criteria for and statistics of Electron Diffusion regions associated with subsolar magnetic field reconnection
    Journal of Geophysical Research, 2005
    Co-Authors: F. S. Mozer
    Abstract:

    [1] The definition of “Electron Diffusion regions” and criteria for identifying them in magnetic field reconnection events are given. By employing these criteria and further constraints on the measured parallel electric field, 117 Electron Diffusion regions have been found in searching through 3 years of Polar satellite subsolar data. They exist in filamentary currents in which parallel electric fields and depressed plasma densities are found and where the Electron beta is generally less than 1. The average parallel electric field in these events is about 30% of the average 38 mV/m perpendicular field. The size of these regions is the order of the Electron skin depth or less. These Electron Diffusion regions are topological boundaries in the Electron and magnetic field line flows because the components of E × B/B2 on their opposite sides are frequently different. These regions are found throughout the magnetopause but mainly at the magnetospheric separatrix. The divergence of the pressure tensor in the Generalized Ohm's Law may be the leading term that balances the parallel electric field if the observed large plasma density variations (and hence Electron pressure variations) were spatial and not temporal. The picture resulting from this data is of a magnetopause that is highly structured and filamentary and very different from a linear, laminar, symmetric structure sometimes considered in theories or simulations. However, it is emphasized that events such as those described have been found in fewer than 20% of the magnetopauses examined, so the conventional picture may be more prevalent.

  • Observations of Electron Diffusion regions at the subsolar magnetopause.
    Physical Review Letters, 2003
    Co-Authors: F. S. Mozer, Stuart D. Bale, T. D. Phan, Osborne Ja
    Abstract:

    : Electric and magnetic field observations on the Polar satellite at the subsolar magnetopause show that the magnetopause current is often striated. The largest of the resulting current channels are interpreted as Electron Diffusion regions because their widths are several Electron skin depths and the Electron flow U(e) within them does not satisfy E-->+U-->(e)xB-->=0. The data suggest that the magnetopause contains many such Electron Diffusion regions and that they are required because E-->xB-->/B(2) drifting Electrons cannot carry the large filamentary currents imposed on the local plasma. The most probable interpretation of E-->+U-->(e)xB--> not equal 0 is that the pressure term on the right side of the generalized Ohm's law balances this inequality.

L J Chen - One of the best experts on this subject based on the ideXlab platform.

  • Electron Diffusion regions in magnetotail reconnection under varying guide fields
    Geophysical Research Letters, 2019
    Co-Authors: L J Chen, R E Ergun, Shenghsiang Wang, M Hesse, T E Moore, B Giles, Naoki Bessho, C T Russell
    Abstract:

    Kinetic structures of Electron Diffusion regions (EDRs) under finite guide fields in magnetotail reconnection are reported. The EDRs with guide fields 0.14–0.5 (in unit of the reconnecting component) are detected by the Magnetospheric Multiscale spacecraft. The key new features include the following: (1) cold inflowing Electrons accelerated along the guide field and demagnetized at the magnetic field minimum while remaining a coherent population with a low perpendicular temperature, (2) wave fluctuations generating strong perpendicular Electron flows followed by alternating parallel flows inside the reconnecting current sheet under an intermediate guide field, and (3) gyrophase bunched Electrons with high parallel speeds leaving the X‐line region. The normalized reconnection rates for the three EDRs range from 0.05 to 0.3. The measurements reveal that finite guide fields introduce new mechanisms to break the Electron frozen‐in condition.

  • Electron Diffusion region during magnetopause reconnection with an intermediate guide field magnetospheric multiscale observations
    Journal of Geophysical Research, 2017
    Co-Authors: J. L. Burch, R E Ergun, L J Chen, Shenghsiang Wang, M Hesse, Daniel J Gershman, N Bessho
    Abstract:

    An Electron Diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale space ...

  • magnetospheric multiscale mission observations of the outer Electron Diffusion region
    Geophysical Research Letters, 2017
    Co-Authors: Yuri V. Khotyaintsev, R E Ergun, L J Chen, E Choi, D G Sibeck, Kyoungjoo Hwang, B L Giles
    Abstract:

    This paper presents Magnetospheric Multiscale mission (MMS) observations of the exhaust region in the vicinity of the central reconnection site in Earth's magnetopause current sheet. High-time-resolution measurements of field and particle distributions enable us to explore the fine structure of the Diffusion region near the X line. Ions are decoupled from the magnetic field throughout the entire current sheet crossing. Electron jets flow downstream from the X line at speeds greater than the E × B drift velocity. At/around the magnetospheric separatrix, large-amplitude electric fields containing field-aligned components accelerate Electrons along the magnetic field toward the X line. Near the neutral sheet, crescent-shaped Electron distributions appear coincident with (1) an out-of-plane electric field whose polarity is opposite to that of the reconnection electric field and (2) the energy transfer from bulk kinetic to field energy. The observations indicate that MMS passed through the edge of an elongated Electron Diffusion region (EDR) or the outer EDR in the exhaust region.

  • kinetic structure of the Electron Diffusion region in antiparallel magnetic reconnection
    Physical Review Letters, 2011
    Co-Authors: Jonathan Ng, J Egedal, A Le, W Daughton, L J Chen
    Abstract:

    Strong Electron pressure anisotropy has been observed upstream of Electron Diffusion regions during reconnection in Earth's magnetotail and kinetic simulations. For collisionless antiparallel reconnection, we find that the anisotropy drives the Electron current in the Electron Diffusion region, and that this current is insensitive to the reconnection electric field. Reconstruction of the Electron distribution function within this region at enhanced resolutions reveals its highly structured nature and the mechanism by which the pressure anisotropy sets the structure of the region.

J. L. Burch - One of the best experts on this subject based on the ideXlab platform.

  • Electron vorticity indicative of the Electron Diffusion region of magnetic reconnection
    Geophysical Research Letters, 2019
    Co-Authors: K J Hwang, J. L. Burch, B L Giles, C J Pollock, E Choi, Kyunghwan Dokgo, D G Sibeck, M L Goldstein, W R Paterson, Huimin Fu
    Abstract:

    Author(s): Hwang, K-J; Choi, E; Dokgo, K; Burch, JL; Sibeck, DG; Giles, BL; Goldstein, ML; Paterson, WR; Pollock, CJ; Shi, QQ; Fu, H; Hasegawa, H; Gershman, DJ; Khotyaintsev, Y; Torbert, RB; Ergun, RE; Dorelli, JC; Avanov, L; Russell, CT; Strangeway, RJ | Abstract: While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced Electron vorticity in the vicinity of the Electron Diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying Electron jets in the direction along the Electron meandering motion or out-of-plane direction, agyrotropic Electron distribution functions, and dissipative signatures. At the edge of the Electron jets, the Electron vorticity increased with magnitudes greater than the Electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that Electron vorticity can act as a proxy for delineating the Electron Diffusion region of magnetic reconnection.

  • Evidence of Magnetic Nulls in Electron Diffusion Region
    Geophysical Research Letters, 2019
    Co-Authors: Huimin Fu, Zhihua Wang, Andris Vaivads, Yuri V. Khotyaintsev, J. L. Burch, Shiyong Huang
    Abstract:

    Theoretically, magnetic reconnection—the process responsible for solar flares and magnetospheric substorms—occurs at the X‐line or radial null in the Electron Diffusion region (EDR). However, wheth ...

  • magnetospheric multiscale dayside reconnection Electron Diffusion region events
    Journal of Geophysical Research, 2018
    Co-Authors: J M Webster, J. L. Burch, P H Reiff, Antoun G Daou, K J Genestreti, Daniel B Graham, R B Torbert, R E Ergun, S Sazykin, A Marshall
    Abstract:

    We use high-resolution data from dayside passes of the Magnetospheric Multiscale (MMS) mission to create for the first time a comprehensive listing of encounters with the Electron Diffusion region ...

  • instability of agyrotropic Electron beams near the Electron Diffusion region
    Physical Review Letters, 2017
    Co-Authors: Daniel B Graham, Andris Vaivads, Yuri V. Khotyaintsev, J. L. Burch, J M Webster, R E Ergun, M Andre, C Norgren, Perarne Lindqvist, R B Torbert
    Abstract:

    During a magnetopause crossing the Magnetospheric Multiscale spacecraft encountered an Electron Diffusion region (EDR) of asymmetric reconnection. The EDR is characterized by agyrotropic beam and c ...

  • Electron Diffusion region during magnetopause reconnection with an intermediate guide field magnetospheric multiscale observations
    Journal of Geophysical Research, 2017
    Co-Authors: J. L. Burch, R E Ergun, L J Chen, Shenghsiang Wang, M Hesse, Daniel J Gershman, N Bessho
    Abstract:

    An Electron Diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale space ...