On the origin of high-energy particles in the cusp diamagnetic cavity

Nykyri, K.; Otto, A.; Adamson, E.; Kronberg, Elena A.; Daly, P. W.

doi:10.1016/j.jastp.2011.08.012

Cited by 45 publications

(78 citation statements)

References 39 publications

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“…The extended current sheet demonstrated properties of a hot diamagnetic region and features of a mirror mode structure or magnetic hole, the first time such a structure has been found in the ionosphere of Mars. Observations suggests lower energy electrons could be accelerated by a local process of perpendicular heating/pitch angle diffusion and supports similar results at the Earth's polar cusp reported by Nykyri et al (Nykyri et al [2012]. J. Atmos.…”

supporting

confidence: 89%

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

Soobiah

Wild

Beharrell

et al. 2014

Icarus

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a b s t r a c tWe present dual spacecraft observations by MGS MAG/ER and MEX ASPERA-3 ELS of a large-scale magnetic flux rope on the dayside of Mars that occurs in close proximity to the crustal magnetic fields and a dayside current sheet region. A current sheet (including the large-scale flux rope) was observed on repeated MGS orbits when the draped solar wind magnetic field present in the ionosphere had a þB y component (in MSO). Minimum Variance Analysis (MVA) of the large-scale flux rope and two current sheet crossings that occur after show a common peak in magnetic field along the intermediate variance direction, indicating the normal component of a reconnecting current sheet. All repeated orbits demonstrated evidence of a plasma boundary by the decrease in electron differential flux above 100 eV when moving into regions dominated by the crustal magnetic field, and coincided with the measured magnetic field strength being double the undisturbed crustal magnetic field. We argue this forms evidence of magnetic reconnection between crustal magnetic fields and draped solar wind magnetic field (from ionosphere or magnetosheath) at a ''mini-magnetopause'' type boundary on the dayside of Mars. Similar electron pitch angle distributions observed during the large-scale flux rope, current sheet crossings, and regions of radial crustal magnetic field, suggest these regions share a common magnetic field topology for the trapping of magnetosheath particles on open crustal magnetic fields on the dayside of Mars. As such, indicates a trapping quadrupole magnetic field exist either at the magnetic reconnection X-line region or where open crustal magnetic fields meet oppositely directed solar wind magnetic field. At a time when the draped solar wind magnetic field present in the ionosphere was weaker in strength, the current sheet crossing was observed over an extended region of 2000 km. The extended current sheet demonstrated properties of a hot diamagnetic region and features of a mirror mode structure or magnetic hole, the first time such a structure has been found in the ionosphere of Mars. Observations suggests lower energy electrons could be accelerated by a local process of perpendicular heating/pitch angle diffusion and supports similar results at the Earth's polar cusp reported by Nykyri et al. (Nykyri et al. [2012]. J. Atmos. Sol-Terr. Phys. 87, 70). Such large scale and energetic structures are usually associated with regions beyond a planet's ionosphere, and the occurrence within the ionosphere of Mars may have an important impact on escape processes and the evolution of the martian atmosphere.

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supporting

confidence: 89%

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

Soobiah

Wild

Beharrell

et al. 2014

Icarus

View full text Add to dashboard Cite

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“…Observations (Walsh et al, 2010) and modeling (Nykyri et al, 2012) have shown electrons heated through drift acceleration in the cusp diamagnetic cavity are peaked at a pitch angle of 90 • in a local magnetic field minimum. Field strengths in the cusp diamagnetic cavity range between 10 nT and 40 nT (e.g.…”

Section: Exterior Cuspmentioning

confidence: 99%

“…Modeling by Nykyri et al (2012) has shown the presence of energetic electrons in the cusp is due to local heating via drift acceleration. As the particle gradients drift around the magnetic minimum in the cusp, they can gain energy as they travel through the electric potential created due to dayside reconnection.…”

Section: Exterior Cuspmentioning

confidence: 99%

“…Each source is tested in the current study to determine which is most consistent with observations. The exterior cusp has been shown to be capable of heating electrons to several hundred keV under certain conditions (Walsh et al, 2010;Nykyri et al, 2012). This energetic electron population is typically peaked at a pitch angle of 90 • and trapped within a magnetic cavity in the exterior cusp.…”

Section: Introductionmentioning

confidence: 99%

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Energetic electrons along the high-latitude magnetopause

et al. 2012

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Abstract.A case study is presented to determine the source of the energetic electron layer frequently observed along the high-latitude magnetopause. Measurements by the Cluster spacecraft show bursts of field-aligned electrons occurring during time periods with high potential for dayside reconnection. These properties are compared with the expected signatures from several sources including escape from the exterior cusp, acceleration in a reconnection region, and release from the dayside trapping region through reconnection. The observed properties are most consistent with the electrons being released from the magnetosphere due to reconnection. In this model the electrons would flow along the newly reconnected IMF draped along the magnetopause and propagate along the high-latitude magnetopause. These observations demonstrate an active source for populating the energetic particle layer frequently observed along and just outside the high-latitude magnetopause.

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“…Fritz et al, 2003;Whitaker et al, 2007) examined propagation constraints on the energetic particles, finding that particles drifting to the cusp from other candidate acceleration regions would need to violate adiabatic invariants. Nykyri et al (2012) extended both the drift constraints and cusp modeling. However, Trattner et al (2010) presented examples of CEPs unassociated with diamagnetic cavities.…”

Section: Introductionmentioning

confidence: 99%

Association of cusp energetic ions with geomagnetic storms and substorms

2012

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Abstract. Energetic ions observed in the cusp have been explained as a result of processes within the magnetosphere, but also proposed as a driver of some of those same processes. This study assesses potential connections between energetic ions observed in the cusp and geomagnetic storm and substorm activity. These connections may suggest sources of cusp energetic particles (CEPs), or imply effects of these particles on magnetospheric dynamics. We identify CEPs from six years of cusp crossings by the Polar satellite, relating them to storm and substorm onsets. CEPs showed no significant dependence on storms but did show a weak, statistically significant, increase after substorm onsets. CEPs had no significant association with subsequent storm or substorm onsets. We conclude that substorm acceleration may contribute to CEPs but CEPs are unlikely to contribute to global magnetospheric dynamics.

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On the origin of high-energy particles in the cusp diamagnetic cavity

Cited by 45 publications

References 39 publications

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

Properties of a large-scale flux rope and current sheet region on the dayside of Mars: MGS MAG/ER and MEX ASPERA-3 ELS observations

Energetic electrons along the high-latitude magnetopause

Association of cusp energetic ions with geomagnetic storms and substorms

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