Cold ion demagnetization near the X‐line of magnetic reconnection

Toledo‐Redondo, Sergio; André, Mats; Khotyaintsev, Yuri V.; Vaivads, A.; Walsh, A. P.; Li, Wenya; Graham, Daniel B.; Lavraud, B.; Masson, A.; Aunai, N.; Divin, Andrey; Dargent, Jérémy; Fuselier, S. A.; Gershman, D. J.; Dorelli, J.; Giles, B. L.; Avanov, L. A.; Pollock, C. J.; Saito, Y.; Moore, T. E.; Coffey, V. N.; Chandler, M. O.; Lindqvist, Per‐Arne; Torbert, R. B.; Russell, C. T.

doi:10.1002/2016gl069877

Cited by 38 publications

(49 citation statements)

References 36 publications

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“…Though small compared to the electric field seen in the later exhaust, there is an increase in E N and E M as MMS4 samples the separatrix region at 06:38:55–06:39:10 UT and at 06:39:25–06:39:40 UT. The low‐energy ions in Figure d do increase in energy as the energy associated with the E × B drift increases, consistent with previous observations (e.g., Toledo‐Redondo, André, Vaivads, et al, , Toledo‐Redondo, André, Khotyaintsev, et al, ) and with the ring distributions arising from a rapidly changing electric field.…”

Section: Encounters With the Llbl Separatrixmentioning

confidence: 99%

“…For magnetospheric plasma reaching the magnetopause, the temperature of the plasma can have an effect on reconnection. The presence of cold plasma (like that of the plasmaspheric plume) has been shown to introduce a new length scale for diffusion regions and can alter the Hall currents at the reconnection site (André et al, ; Toledo‐Redondo, André, Vaivads, et al, ; Toledo‐Redondo, André, Khotyaintsev, et al, ). A cold plasma population reaching the magnetopause may also alter the instabilities within the separatrix region (André et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Magnetospheric Ion Evolution Across the Low‐Latitude Boundary Layer Separatrix

et al. 2017

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On 20 September 2015, the Magnetospheric Multiscale (MMS) spacecraft crossed the dusk magnetopause after a compression of the magnetosphere. Enhanced densities and fluxes of both colder (≤10 eV) and hotter (>1 keV) magnetospheric and magnetosheath heavy ion species were observed reaching the magnetopause. The evolution of the velocity distributions for H+, He+, and O+ measured by the Hot Plasma Composition Analyzer on MMS during this magnetopause crossing is presented. In particular, this study focuses on the changes in the species' distribution functions as MMS passes from the magnetosphere through the electron edge of the low‐latitude boundary layer (LLBL) separatrix and then into the LLBL. Two types of processes are suggested to play a role in the heating of colder magnetospheric ions across the LLBL separatrix in the region between the separatrix and the electron and ion edges of the LLBL. One mechanism leads to the formation and enhancement of ring distributions in this layer of the LLBL as the magnetospheric ions propagate across the separatrix. A second mechanism leading first to perpendicular heating and then to parallel heating of colder protons may arise from a possible two‐stream instability as the magnetospheric ions first encounter the warmer magnetosheath electrons in the electron layer and then the warmer magnetosheath ions between the electron and ion edges of the LLBL separatrix. Perpendicular heating of He+ and O+ is seen more so in the main reconnection exhaust, due to nonadiabatic behavior of these ions as they are accelerated up to the bulk flow speed.

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Section: Encounters With the Llbl Separatrixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetospheric Ion Evolution Across the Low‐Latitude Boundary Layer Separatrix

et al. 2017

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“…However, there are multiple sources of magnetospheric ions and electrons; these sources are highly variable, and there are times and locations when one of these magnetospheric plasma sources may rival the magnetosheath source. During these times and at these locations, reconnection regions at the magnetopause may be modified (e.g., André et al, 2016;Dargent et al, 2017;Toledo-Redondo et al, 2016;Wang et al, 2014) and reconnection rates may be adversely affected (Cassak & Shay, 2007).…”

Section: Introductionmentioning

confidence: 99%

Mass Loading the Earth's Dayside Magnetopause Boundary Layer and Its Effect on Magnetic Reconnection

Fuselier

Trattner

Petrinec

et al. 2019

Geophysical Research Letters

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When the interplanetary magnetic field is northward for a period of time, O+ from the high‐latitude ionosphere escapes along reconnected magnetic field lines into the dayside magnetopause boundary layer. Dual‐lobe reconnection closes these field lines, which traps O+ and mass loads the boundary layer. This O+ is an additional source of magnetospheric plasma that interacts with magnetosheath plasma through magnetic reconnection. This mass loading and interaction is illustrated through analysis of a magnetopause crossing by the Magnetospheric Multiscale spacecraft. While in the O+‐rich boundary layer, the interplanetary magnetic field turns southward. As the Magnetospheric Multiscale spacecraft cross the high‐shear magnetopause, reconnection signatures are observed. While the reconnection rate is likely reduced by the mass loading, reconnection is not suppressed at the magnetopause. The high‐latitude dayside ionosphere is therefore a source of magnetospheric ions that contributes often to transient reduction in the reconnection rate at the dayside magnetopause.

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“…They fill the magnetotail lobes and coexist with hot ions in the plasma sheet (Seki et al, ). At the magnetic reconnection site, they introduce a smaller decoupling region of the size of the gyroradius than that of hot ions (Toledo‐Redondo et al, ), reduce the Hall current carried by electrons (André et al, ), and affect the dynamics of magnetic reconnection.…”

Section: Introductionmentioning

confidence: 99%

Cold Ion Outflow Modulated by the Solar Wind Energy Input and Tilt of the Geomagnetic Dipole

Wei

André

et al. 2017

JGR Space Physics

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The solar wind energy input into the Earth's magnetosphere‐ionosphere system drives ionospheric outflow, which plays an important role in both the magnetospheric dynamics and evolution of the atmosphere. However, little is known about the cold ion outflow with energies lower than a few tens of eV, as the direct measurement of cold ions is difficult because a spacecraft gains a positive electric charge due to the photoemission effect, which prevents cold ions from reaching the onboard detectors. A recent breakthrough in the measurement technique using Cluster spacecraft revealed that cold ions dominate the ion population in the magnetosphere. This new technique yields a comprehensive data set containing measurements of the velocities and densities of cold ions for the years 2001–2010. In this paper, this data set is used to analyze the cold ion outflow from the ionosphere. We found that about 0.1% of the solar wind energy input is transformed to the kinetic energy of cold ion outflow at the topside ionosphere. We also found that the geomagnetic dipole tilt can significantly affect the density of cold ion outflow, modulating the outflow rate of cold ion kinetic energy. These results give us clues to study the evolution of ionospheric outflow with changing global magnetic field and solar wind condition in the history.

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Cold ion demagnetization near the X‐line of magnetic reconnection

Cited by 38 publications

References 36 publications

Magnetospheric Ion Evolution Across the Low‐Latitude Boundary Layer Separatrix

Magnetospheric Ion Evolution Across the Low‐Latitude Boundary Layer Separatrix

Mass Loading the Earth's Dayside Magnetopause Boundary Layer and Its Effect on Magnetic Reconnection

Cold Ion Outflow Modulated by the Solar Wind Energy Input and Tilt of the Geomagnetic Dipole

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