Energetic particle injections into the outer cusp during compression events

Delcourt, Dominique; Malova, H. V.; Zelenyǐ, L. M.; Sauvaud, J. A.; Moore, T. E.; Fok, M.‐C.

doi:10.1186/bf03352556

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…In addition to the nightside plasma sheet proton, cusp trapped proton is another probable source of the ring current during weak solar wind enforcement 34 . Opposite transport (i.e., from the ring current to the cusp trapping region) may occur after a sudden enhancement in solar wind p dyn 49 . Additionally, planetary ions such as sodium ions may also be a significant carrier of the ring current, as indicated by simulation results in Exner et al 28 , Paral et al 35 , and Yagi et al 36 .…”

Section: Discussionmentioning

confidence: 99%

Observational evidence of ring current in the magnetosphere of Mercury

et al. 2022

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The magnetic gradient and curvature drift of energetic ions can form a longitudinal electric current around a planet known as the ring current, that has been observed in the intrinsic magnetospheres of Earth, Jupiter, and Saturn. However, there is still a lack of observational evidence of ring current in Mercury’s magnetosphere, which has a significantly weaker dipole magnetic field. Under such conditions, charged particles are thought to be efficiently lost through magnetopause shadowing and/or directly impact the planetary surface. Here, we present the observational evidence of Mercury’s ring current by analysing particle measurements from MErcury Surface, Space Environment, GEochemistry, and Ranging (MESSENGER) spacecraft. The ring current is bifurcated because of the dayside off-equatorial magnetic minima. Test-particle simulation with Mercury’s dynamic magnetospheric magnetic field model (KT17 model) validates this morphology. The ring current energy exceeds $$5\times {10}^{10}$$ 5 × 10 10 J during active times, indicating that magnetic storms may also occur on Mercury.

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Section: Discussionmentioning

confidence: 99%

Observational evidence of ring current in the magnetosphere of Mercury

et al. 2022

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“…Recently, Chen et al [2004] reported that (1) turbulent cusp electric field with an amplitude of about 100 mV/m has been detected by Polar; (2) dominated by its perpendicular components, the cusp electric field spectral density for fluctuations in the ULF range shows orders of magnitude increases; and (3) both left‐ and right‐hand polarizations have been measured. The CEPs could also be energized in the CDC by an adiabatic compression [ Sheldon et al , 2005] or in the outer cusp by a large transient electric field associated with violation of adiabatic invariants [ Delcourt et al , 2005].…”

Section: Discussionmentioning

confidence: 99%

Multiple spacecraft observations of energetic ions during a high solar wind pressure event

2005

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[1] On 28 June 1999 the Wind spacecraft (near the forward libration point) observed a large solar wind pressure spike from 0445 UT to 0600 UT. The Polar satellite at 7 hours magnetic local time detected an energetic particle event in the high-altitude region associated with turbulent diamagnetic cavities from 0512 UT to 0627 UT. The particles and cavities are very similar to those that were previously found in the high-altitude dayside cusp region. They are independent of both the solar wind velocity and the interplanetary magnetic field (IMF) vectors. The enhancements of the magnetic field fluctuations in the ultra-low frequency range measured by the Wind were also observed by the Polar. Most of the time, during the event period, the IMF had a duskward component, suggesting that cusp diamagnetic cavities also existed in the postnoon sector in the Northern Hemisphere. Energetic ions of both ionospheric origin and solar wind origin were observed by the Polar spacecraft during this event period. The He ++ /H + ratio in the diamagnetic cavities was a factor of four higher than in the quasi-trapping region before the event onset, while the He + /He ++ ratio in the cavities was more than one order of the magnitude lower. In this event, the measured cusp ions had energies up to 4 MeV. No clear relationship between the cusp energetic ion flux and the IMF cone angle was found. The Interball 1 spacecraft located just upstream of the bow shock in the prenoon sector measured an upstream ion event from about 0516 UT to 0600 UT. The onset of the energetic ions observed by Interball 1 in the upstream event was the same for different energies; the ion energy spectra were independent of the solar wind velocity and their intensities were independent of the bow shock geometry and the solar wind density. The energetic ion event onset was first detected in the cusp by Polar at 0512 UT, then near the bow shock in the prenoon by Interball 1 at 0516 UT, and then in the far upstream by Wind at 0523 UT. The measured energetic ion intensity decreased with increasing distance from the cusp diamagnetic cavities. These observational facts together with the IMF directions suggest that (1) this large solar wind pressure event produced an extremely large diamagnetic cavity (>10 R E ) within the magnetosphere, (2) the bow shock was not the main source of both the cusp and upstream energetic ions, and (3) the upstream energetic ions most likely came from the cusp.

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“…For example, if the cusp were always shrinking, say, by a continually increasing solar wind pressure, then betatron acceleration would energize the particles in the same direction. This has been modeled by Delcourt et al (2005) showing significant acceleration. Or if the cusp were always shrinking whenever the particles were at local noon, but expanding at local midnight, then the third drift invariant would be resonant with the cusp disturbance.…”

Section: Fluctuation Powermentioning

confidence: 99%