The THEMIS Digital Fields Board

Cully, C. M.; Ergun, R.; Stevens, Ken; Nammari, Abdullah; Westfall, J.

doi:10.1007/978-0-387-89820-9_15

Cited by 88 publications

(107 citation statements)

References 9 publications

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“…Two ARTEMIS instruments are used in this analysis. The Electric Field Instrument (EFI; Bonnell et al, ; Cully et al, ) and the ElectroStatic Analyzers (ESAs; McFadden et al, ). EFI measures electric fields using six probes at the ends of six booms.…”

Section: Instrumentation and Data Analysismentioning

confidence: 99%

“…Our analysis makes use of the EFI high‐resolution time series data, which consist of ∼5‐ or ∼10‐s bursts of 16,384 samples per second of AC‐coupled (>10 Hz), three‐axis, electric field data E 12 , E 34 , and E 56 . EFI burst data collection is triggered onboard based on the highest‐amplitude signals in a specific frequency passband (Bonnell et al, ; Cully et al, ). A limited amount of automatically selected data is retained in onboard memory for transmission to Earth.…”

Section: Instrumentation and Data Analysismentioning

confidence: 99%

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Prediction and Observation of Electron Instabilities and Phase Space Holes Concentrated in the Lunar Plasma Wake

Hutchinson

Malaspina

2018

Geophysical Research Letters

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Recent theory and numerical simulation predicts that the wake of the solar wind flow past the Moon should be the site of electrostatic instabilities that give rise to electron holes. These play an important role in the eventual merging of the wake with the background solar wind. Analysis of measurements from the ARTEMIS satellites, orbiting the Moon at distances from 1.2 to 11 R M , detects holes highly concentrated in the wake, in agreement with prediction. The theory also predicts that the hole flux density observed should be hollow, peaking away from the wake axis. Observation statistics qualitatively confirm this hollowness, lending extra supporting evidence for the identification of their generation mechanism.Plain Language Summary Analysis of measurements by the ARTEMIS satellites orbiting the Moon shows that, in the lunar plasma wake, isolated electric structures called electron holes are being continuously formed. These holes are regions of depleted electron density that are maintained by their own positive charge. As the solar wind flows supersonically past the Moon, a density-depleted wake of approximate length 20,000 km (10 lunar radii) forms behind it. Plasma streams along the magnetic field fill in the wake, and theory predicts that instabilities should occur giving rise to these holes. They are solitary waves (solitons) consisting of short electric potential humps of width approximately 100 m. Motivated by this theory, ARTEMIS measurements of rapid variations of the electric field around the satellite have been searched for the characteristic signatures of holes. It is found that holes occur extremely frequently when the satellites are in the wake, but only very rarely outside the wake, and that in accordance with theory, the holes occur less frequently at the wake center than part-way out. Citation: Hutchinson, I. H., & Malaspina, D. M. (2018). Prediction and observation of electron instabilities and phase space holes concentrated in the lunar plasma wake. Geophysical Research Letters, 45,[3838][3839][3840][3841][3842][3843][3844][3845]

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Section: Instrumentation and Data Analysismentioning

confidence: 99%

Section: Instrumentation and Data Analysismentioning

confidence: 99%

Prediction and Observation of Electron Instabilities and Phase Space Holes Concentrated in the Lunar Plasma Wake

Hutchinson

Malaspina

2018

Geophysical Research Letters

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“…The three THEMIS inner spacecraft (A, D, and E) have highly elliptical, near equatorial orbits with the perigee ∼1.5 R E and apogee ∼10 R E to ∼12 R E [ Angelopoulos , ] and are ideally suited to study the characteristics of MS waves in the Earth's magnetosphere. Electric and magnetic field variations from below the spin frequency (1/3 Hz) to 4 kHz are measured by the Electric Field Instrument (EFI) [ Bonnell et al ., ] and the Search Coil Magnetometer (SCM) [ Roux et al ., ], respectively, and the Digital Fields Board (DFB) performs data acquisition and signal process thereafter [ Cully et al ., ]. The Electrostatic Analyzer (ESA) can measure electron and ion distributions from several eV to 25 keV [ McFadden et al ., ], and the Solid State Telescope (SST) can measure the particle distributions from 25 keV to 6 MeV.…”

Section: The Themis Database and An Observed Ms Eventmentioning

confidence: 99%

Global distribution of equatorial magnetosonic waves observed by THEMIS

Thorne

et al. 2013

Geophysical Research Letters

145

197

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[1] We investigate the wave magnetic field data from three THEMIS spacecraft over the recent 31 months to perform a statistical study of equatorial magnetosonic (MS) wave properties and spatial distribution. The THEMIS spacecraft provide good data coverage in the dominant MS wave region near the equator and at 2 Ä L Ä 8. Our global survey shows that strong amplitudes and high occurrence of MS waves are generally observed near the equator, outside the plasmapause, on the dawnside during geomagnetically disturbed periods. In addition, increase of geomagnetic activity shifts the MS wave distribution toward earlier magnetic local time. Strong MS waves generally have RMS wave amplitudes 50 pT and an occurrence rate 20% on the dawnside outside the plasmapause and could therefore have an important influence on both ring current ion and energetic electron dynamics in the Earth's radiation belts.

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“…The flux data were originally at either 3 s or 3 min resolution, depending on whether the instrument was in fast or slow survey mode, but all PSD data were interpolated to 1 minute time steps, to align them with the L* calculations. Additional data from the THEMIS fluxgate magnetometers [ Auster et al ., ] and the wave digital fields board [ Cully et al ., ] were also used here for the local field strength (used for calculating μ) and examining wave activity. All THEMIS data were accessed and processed using the THEMIS Data Analysis Software tools.…”

Section: Orientation and Observationsmentioning

confidence: 99%

Competing source and loss mechanisms due to wave‐particle interactions in Earth's outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm

et al. 2014

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Drastic variations of Earth's outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave-particle interactions are critically important. Using 15 spacecraft including NASA's Van Allen Probes, THEMIS, and SAMPEX missions and NOAA's GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm's main phase dropout exhibited enhanced losses to the atmosphere at L* < 4, where the phase space density (PSD) of multi-MeV electrons dropped by over an order of magnitude in <4 h. Based on POES observations of precipitating >1 MeV electrons and energetic protons, SAMPEX >1 MeV electrons, and ground observations of band-limited Pc1-2 wave activity, we show that this sudden loss was consistent with pitch angle scattering by electromagnetic ion cyclotron waves in the dusk magnetic local time sector at 3 < L* < 4. At 4 < L* < 5, local acceleration was also active during the main and early recovery phases, when growing peaks in electron PSD were observed by both Van Allen Probes and THEMIS. This acceleration corresponded to the period when IMF Bz was southward, the AE index was >300 nT, and energetic electron injections and whistler-mode chorus waves were observed throughout the inner magnetosphere for >12 h. After this period, Bz turned northward, and injections, chorus activity, and enhancements in PSD ceased. Overall, the outer belt was depleted by this storm. From the unprecedented level of observations available, we show direct evidence of the competitive nature of different wave-particle interactions controlling relativistic electron fluxes in the outer radiation belt.

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The THEMIS Digital Fields Board

Cited by 88 publications

References 9 publications

Prediction and Observation of Electron Instabilities and Phase Space Holes Concentrated in the Lunar Plasma Wake

Prediction and Observation of Electron Instabilities and Phase Space Holes Concentrated in the Lunar Plasma Wake

Global distribution of equatorial magnetosonic waves observed by THEMIS

Competing source and loss mechanisms due to wave‐particle interactions in Earth's outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm

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