The THEMIS ESA Plasma Instrument and In-flight Calibration

McFadden, J. P.; Carlson, C. W.; Larson, D. E.; Ludlam, M.; Abiad, R.; Elliott, Ben; Turin, P.; Marckwordt, Mario; Angelopoulos, V.

doi:10.1007/s11214-008-9440-2

Cited by 955 publications

(912 citation statements)

References 10 publications

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“…From these measurements, magnetosheath intervals were selected: (i) where THEMIS ion density measurements exceeded twice the solar wind density (see panel b of Fig. 1) as given by the OMNI high-resolution solar wind data set (King and Papitashvili, 2005); (ii) where the differential ion energy flux of 1 keV ions exceeded that of 10 keV ions; and (iii) where THEMIS magnetometer (Auster et al, 2008), electrostatic analyzer (McFadden et al, 2008), and OMNI IMF, ion density, ion velocity, and plasma beta data were available. Note that the OMNI data are already propagated to the bow shock nose.…”

Section: Data Setsmentioning

confidence: 99%

Plasma flow patterns in and around magnetosheath jets

Plaschke¹,

Hietala²

2018

Ann. Geophys.

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Abstract. The magnetosheath is commonly permeated by localized high-speed jets downstream of the quasi-parallel bow shock. These jets are much faster than the ambient magnetosheath plasma, thus raising the question of how that latter plasma reacts to incoming jets. We have performed a statistical analysis based on 662 cases of one THEMIS spacecraft observing a jet and another (second) THEMIS spacecraft providing context observations of nearby plasma to uncover the flow patterns in and around jets. The following results are found: along the jet's path, slower plasma is accelerated and pushed aside ahead of the fastest core jet plasma. Behind the jet core, plasma flows into the path to fill the wake. This evasive plasma motion affects the ambient magnetosheath, close to the jet's path. Diverging and converging plasma flows ahead and behind the jet are complemented by plasma flows opposite to the jet's propagation direction, in the vicinity of the jet. This vortical plasma motion results in a deceleration of ambient plasma when a jet passes nearby.

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Section: Data Setsmentioning

confidence: 99%

Plasma flow patterns in and around magnetosheath jets

Plaschke¹,

Hietala²

2018

Ann. Geophys.

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“…The mission employs five identical satellites. Data from the electrostatic analyzer (ESA) [McFadden et al, 2008] and the solid state telescope (SST) [Angelopoulos, 2008] instruments are used in this study.…”

Section: Themismentioning

confidence: 99%

“…We describe how major features of the evolution appear to be consistent with expectations based upon time dependent geomagnetic indices, e.g., SYM/H and ASY/H, and geosynchronous orbit detection of dipolarizations from GOES 11 and 12. In situ THEMIS ESA [McFadden et al, 2008] and SST [Angelopoulos, 2008] spectral measurements are compared with the temporal and spatial evolution of the energy dependence of the trapped ions in the ring current obtained from the deconvolution of TWINS ENA images.…”

Section: Introductionmentioning

confidence: 99%

Evolution of CIR storm on 22 July 2009

et al. 2012

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[1] Global images of ion intensities are deconvolved from TWINS ENA images during the main and recovery phase of a CIR storm on 22 July 2009. The global spatial ion images taken at different times, along with solar wind data, geomagnetic activity indices, geosynchronous orbit observations, and in situ measurements from the THEMIS mission provide a picture of the evolution of the ring current during both the main phase and early recovery phase of the storm. Major features of the evolution are consistent with expectations based upon time dependent geomagnetic indices, e.g., SYM/H and ASY/H, and geosynchronous orbit detection of dipolarizations from GOES 11 and 12. Direct comparisons are made with in situ THEMIS ESA and SST spectral measurements. The peak energy of the ion spectrum in the ring current is seen to decrease in the recovery phase. The time evolution of the ion energy spectra over the range from 2.5 to 97.5 keV at the spatial peaks of the ring current in the inner magnetosphere obtained from ENA images is presented for the first time.

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“…The apogee of THEMIS A was shifted to ∼12 R E and was against the plasma sheet in the 2009 season. We used the data of the electric field instrument [Bonnell et al, 2008], the fluxgate magnetometer [Auster et al, 2008], the electrostatic analyzer (ESA) [McFadden et al, 2008], and the solid state telescope (SST). These data are given in a 3 s time resolution.…”

Section: Data Setsmentioning

confidence: 99%

Azimuthal auroral expansion associated with fast flows in the near-Earth plasma sheet: Coordinated observations of the THEMIS all-sky imagers and multiple spacecraft

et al. 2011

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[1] Fast azimuthal auroral expansion and poleward expansion are characteristic features of the expansion phase of substorms. In the first study of its kind, we have investigated the azimuthal auroral expansion and its magnetospheric counterpart using data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) all-sky imagers and multiple spacecraft. During the tail season in 2008-2009, we found 16 events of azimuthally expanding aurora that passed near the magnetic footprints of the multiple spacecraft operating in the near-Earth plasma sheet. In the magnetosphere, these events commonly showed fast azimuthal and earthward flows associated with intense electric fields and magnetic dipolarization. The speed of the propagating structure, which was estimated from the time difference of the depolarization observed by the multiple spacecraft, was close to the measured azimuthal plasma flow velocity. We also found that this azimuthal plasma transport was dominated by the E × B drift speed associated with the enhanced electric field. In a statistical analysis, the averaged speeds of the leading edge of the westward and eastward auroral expansion were 8.8 and 5.3 km/s, respectively. When mapped onto the equatorial magnetosphere, these speeds (267 and 162 km/s) were comparable to the averaged azimuthal plasma (E × B) flow speeds observed by the spacecraft, which were 193 (239) km/s in the westward direction and 112 (139) km/s in the eastward direction. Our events showed that E × B flows and auroral expansion predominantly propagated westward, indicating an effect of westward background convection in the Harang flow shear. From these results, we concluded that the azimuthal auroral expansion was closely related to magnetic dipolarization which expanded azimuthally at the E × B drift speed. On the basis of the abrupt formation of the fast E × B flows and their propagation away from the onset location, we suggest that the effects of the intense large-scale electric fields, which are possibly generated through substorm onset turbulence, propagate to the ionosphere along the magnetic field lines and lead to azimuthal expansion of an auroral arc.

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The THEMIS ESA Plasma Instrument and In-flight Calibration

Cited by 955 publications

References 10 publications

Plasma flow patterns in and around magnetosheath jets

Plasma flow patterns in and around magnetosheath jets

Evolution of CIR storm on 22 July 2009

Azimuthal auroral expansion associated with fast flows in the near-Earth plasma sheet: Coordinated observations of the THEMIS all-sky imagers and multiple spacecraft

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