Ion drift simulation of sudden appearance of sub-keV structured ions in the inner magnetosphere

Yamauchi, M.; Ebihara, Yusuke; Nilsson, Hans; Dandouras, I.

doi:10.5194/angeo-32-83-2014

Cited by 7 publications

(20 citation statements)

References 25 publications

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“…This is not unexpected as the population observed by the RPA mode, at these L shells located predominantly outside of the plasmasphere, is generally considered to correspond mainly to detached plumes and is not typically a major component of the plasma in this region [ Dandouras et al , ; Darrouzet et al , ]. On the other hand, the MAG mode observations generally represent the ring current, plasma sheet, and other energized populations [ Dandouras et al , ; Yamauchi et al , , ], a significant proportion of the plasma for the considered L shells. An analysis of case studies where the CODIF instrument on board one spacecraft was operating in MAG mode while the CODIF instrument on board another spacecraft was operating in RPA mode allowed a comparison of these two corresponding populations at approximately the same time.…”

Section: Instrumentation and Data Reductionmentioning

confidence: 95%

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

et al. 2016

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Using ion density data obtained by the CODIF (ion Composition and Distribution Function analyser) instrument on board the Cluster spacecraft, for the interval spanning 2001–2005, an empirical model describing the average ion mass distribution along closed geomagnetic field lines is determined. The empirical model describes the region spanning 5.9≤L < 9.5, with dependences on L shell and magnetic local time included, and represents ions in the energy range of 0.025 to 40 keV/charge. The data reduction process involves the identification and rejection of CODIF data contaminated by penetrating energetic radiation belt particles, found to frequently occur for L < 5.9. Furthermore, a comparison of data with observations of the cold plasma population in the region provides evidence that the CODIF data set is representative of the full plasma population. The variations in average ion mass along the field lines were modeled using a power law form, which maximizes toward the magnetic equatorial plane, with observed power law index values ranging between approximately −2.0 and 0.0. The resulting model illustrates some key features of the average ion mass spatial distribution, such as an average ion mass enhancement at low L in the evening sector, indicating the transport of high‐latitude heavy ion outflows to the closed inner magnetosphere.

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Section: Instrumentation and Data Reductionmentioning

confidence: 95%

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

et al. 2016

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“…CC BY 4.0 License. keV ions in the dayside (Ebihara et al, 2001(Ebihara et al, , 2004Yamauchi et al, 2009aYamauchi et al, , 2014b. The superposed statistics sorted in terms of the delay-time from the substorm onset (injection of the sub-keV ions) also showed a sudden decrease of the observation rate of "substorm fossil" ions when these ions reaches the noon sector (Yamauchi and Lundin, 2006).…”

Section: Loss Processmentioning

confidence: 91%

“…Cluster CODIF perigee observation on 9 July 2001 and its ion drift simulation using Volland-Stern electric field model(Yamauchi et al, 2014b). Three types of sub-keV ions (eastward drifting energy range) are convoluted in the ion data (i) recently injected nearly field-aligned suprathermal ions during 05:15-05:35 UT, (ii) equatorially-trapped perpendicularly heated plasmasheric ion at 05:59-06:02 UT, and (iii) arch-like dispersed ions during 05:50-06:50 UT.…”

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confidence: 99%

Terrestrial ion circulation in space

Yamauchi¹

2019

Preprint

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Abstract. Observations of the terrestrial ion transport and budget in the magnetosphere are reviewed, with stress on low energy ions in the high-altitude polar region and inner magnetosphere, for which Cluster significantly improved the knowledge. Outflowing ions from the ionosphere are classified into three types in terms of energy: (1) as cold ions refilling the plasmasphere faster than Jeans escape, (2) as cold supersonic ions such as the polar wind, and (3) as suprathermal ions energized by wave-particle interaction or parallel potential acceleration. Majority of the suprathermal ions are further energized at higher altitudes becoming hot with much higher velocity than the escape velocity even for heavy ions. This makes heavy ions in this category more abundant than cold refilling or cold supersonic flow. The immediate destination of these terrestrial ions varies from the plasmasphere, the inner magnetosphere including those entering to the ionosphere in the other, the magnetotail, and the solar wind (magnetosheath and cusp/plasma mantle). Due to time variable return from the magnetotail, ions with different routes and energy meet in the inner magnetosphere, making it a zoo of different types of ions in both energy and energy distribution. This zoo is not yet completely entangled, and includes many unanswered phenomena such as mass-dependent energization although the mass-independent drift theory is well justified. Nearly half of heavy ions in this zoo also finally escape to space, mainly due to magnetopause shadowing (overshooting of ion drift beyond the magnetopause) and charge exchange near the mirror altitude where the exospheric neutral density is the highest. The amount of heavy ions mixing with the solar wind is already the same or larger than that into the magnetotail, and is large enough to directly extract the solar wind kinetic energy in the cusp/plasma mantle through the mass-loading effect and drive the cusp current system. Considering the past solar and solar wind conditions, ion escape might have even influenced the evolution of the terrestrial biosphere.

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“…Although this He + event lasted nearly an hour, which is enough to cause some dispersion at this energy according to both past observations and simulations [ Yamauchi et al ., , ], the energization location is expected to be close to the spacecraft location because there is no energy‐time (energy‐latitude) dispersion in Figures b, h, and n. Instead, the highest He + energy flux density was found at a rather constant energy (around 70 eV) while the intensity decreased during 08:01–08:08 UT in Cluster‐1 and 08:23–08:32 UT in Cluster‐4.…”

Section: Cluster Observationsmentioning

confidence: 94%

Cluster observations of hot He⁺ events in the inner magnetosphere

et al. 2014

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In the inner magnetosphere inside 65°invariant latitude, Cluster Ion Spectrometry detected hot He + events of about a few tens to several hundred eV without the same types of hot H + signature at the same energy. During the 2001-2006 period when the Cluster orbit was almost constant and approximately north-south symmetric at constant local time near the perigee, we found nearly 20 examples in Cluster spacecraft 4. These hot He + events are morphologically classified into two burst types and two dispersed types: (1) Short intensification of He + (1a) without corresponding H + or O + signatures, or (1b) with H + signature at different pitch angles. (2) Energy-latitude dispersed He + stripes that continues for tens of minutes at hundreds to a few thousand eV range (2a) at different drift shell from energy-latitude dispersed H + stripes, or (2b) with very weak H + signature if the energy is constant. While type-1a is observed during or right after substorm activities, type-2b is found after long quiet periods, i.e., after long drift. The relationship with the geomagnetic activity indicates that the plasmasphere can be energized in a mass-dependent way in the evening sector during substorms to form the bursty types (type-1), while the selective He + energization can also take place during quiet periods near the noon. On the other hand, the source of the two dispersed types (type-2) must be remote from the observation point, and the location and the geomagnetic conditions at the time of the He + filtering is an open question.

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Ion drift simulation of sudden appearance of sub-keV structured ions in the inner magnetosphere

Cited by 7 publications

References 25 publications

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

Terrestrial ion circulation in space

Cluster observations of hot He⁺ events in the inner magnetosphere

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Ion drift simulation of sudden appearance of sub-keV structured ions in the inner magnetosphere

Cited by 7 publications

References 25 publications

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

A statistical study of magnetospheric ion composition along the geomagnetic field using the Cluster spacecraft forLvalues between 5.9 and 9.5

Terrestrial ion circulation in space

Cluster observations of hot He+ events in the inner magnetosphere

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Cluster observations of hot He⁺ events in the inner magnetosphere