The Electron Drift Instrument for MMS

Torbert, R. B.; Vaith, H.; Granoff, M.; Widholm, M.; Gaidos, J. A.; Briggs, B. H.; Dors, I.; Chutter, M.; Macri, J.; Argall, M. R.; Bodet, D.; Needell, J.; Steller, M.; Baumjohann, W.; Nakamura, R.; Plaschke, Ferdinand; Öttacher, H.; Hasiba, J.; Hofmann, K.R.; Kletzing, C. A.; Bounds, S. R.; Dvorský, Richard; Sigsbee, K.; Kooi, V.

doi:10.1007/978-94-024-0861-4_10

Cited by 22 publications

(28 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Time intervals with both ASPOC on and off have been considered, while observations when the Electron Drift Instrument (Torbert et al, ) was operating in electric field mode were excluded for this study.…”

Section: Discussionmentioning

confidence: 99%

Plasma Density Estimates From Spacecraft Potential Using MMS Observations in the Dayside Magnetosphere

et al. 2018

Self Cite

View full text Add to dashboard Cite

Using spacecraft potential observations with and without active spacecraft potential control (on/off) from the Magnetospheric Multiscale (MMS) mission, we estimate the average photoelectron emission as well as derive the plasma density information from spacecraft potential variations and active spacecraft potential control ion current. Such estimates are of particular importance especially during periods when the plasma instruments are not in operation and also when electron density observations with higher time resolution than the ones available from particle detectors are necessary. We compare the average photoelectron emission of different spacecraft and discuss their differences. We examine several time intervals when we performed our density estimations in order to understand the strengths and weaknesses of our data set. We finally compare our derived density estimates with the plasma density observations provided by plasma detectors onboard MMS, whenever available, and discuss the overall results. The estimated electron densities should only be used as a proxy of the electron density, complimentary to the plasma moments derived by plasma detectors, especially when the latter are turned off or when higher time resolution observations are required. While the derived data set can often provide valuable information about the plasma environment, the actual values may often be very far from the actual plasma density values and should therefore be used with caution.

show abstract

Section: Discussionmentioning

confidence: 99%

Plasma Density Estimates From Spacecraft Potential Using MMS Observations in the Dayside Magnetosphere

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The MMS spacecraft has spent a large amount of time in the magnetosheath and has crossed the magnetopause many times to capture the dynamics of the magnetic reconnection (Burch et al, ), and it has provided many observations of mirror mode structures in the magnetosheath. One of the unique features of MMS mission is the high time resolution of particle and field measurements when the spacecraft is in burst mode (Baker et al, ; Ergun et al, ; Fuselier et al, ; Le Contel et al, ; Lindqvist et al, ; Pollock et al, ; Russell et al, ; Torbert et al, ). Using burst mode MMS data, there have been recent studies of whistler waves in the magnetosheath associated with mirror mode structures (Breuillard et al, ).…”

Section: Mms Observationsmentioning

confidence: 99%

Generation of Electron Whistler Waves at the Mirror Mode Magnetic Holes: MMS Observations and PIC Simulation

et al. 2018

Self Cite

View full text Add to dashboard Cite

The Magnetospheric Multiscale mission has observed electron whistler waves at the center and at the edges of magnetic holes in the dayside magnetosheath. The magnetic holes are nonlinear mirror structures since their magnitude is anticorrelated with particle density. In this article, we examine the growth mechanisms of these whistler waves and their interaction with the host magnetic hole. In the observations, as magnetic holes develop and get deeper, an electron population gets trapped and develops a temperature anisotropy favorable for whistler waves to be generated. In addition, the decrease in magnetic field magnitude and the increase in density reduce the electron resonance energy, which promotes the electron cyclotron resonance. To investigate this process, we used expanding box particle‐in‐cell simulations to produce the mirror instability, which then evolve into magnetic holes. The simulation shows that whistler waves can be generated at the center and edges of magnetic holes, which reproduces the primary features of the MMS observations. The simulation shows that the electron temperature anisotropy develops in the center of the magnetic hole once the mirror instability reaches its nonlinear stage of evolution. The plasma is then unstable to whistler waves at the minimum of the magnetic field structures. In the saturation regime of mirror instability, when magnetic holes are developed, the electron temperature anisotropy appears at the edges of the holes and electron distributions become more isotropic at the magnetic field minimum. At the edges, the expansion of magnetic holes decelerates the electrons, which leads to temperature anisotropies.

show abstract

“…These currents vary depending on which mode the spacecraft is operating in. Specifically, V SC is determined by whether Active Spacecraft Potential Control (ASPOC; Torkar et al, ) is off or on, and whether or not the Electron Drift Instrument (EDI; Torbert et al, ) is operating in electric field mode. When ASPOC is on, V SC is reduced to low values

≲

5 V by emitting ion beams, with a nominal current of 20 μA.…”

Section: Mms Datamentioning

confidence: 99%

Enhanced Escape of Spacecraft Photoelectrons Caused by Langmuir and Upper Hybrid Waves

et al. 2018

Self Cite

View full text Add to dashboard Cite

The spacecraft potential is often used to infer rapid changes in the thermal plasma density. The variations in spacecraft potential associated with large‐amplitude Langmuir and upper hybrid waves are investigated with the Magnetospheric Multiscale (MMS) mission. When large‐amplitude Langmuir and upper hybrid waves are observed, the spacecraft potential increases. The changes in spacecraft potential are shown to be due to enhanced photoelectron escape from the spacecraft when the wave electric fields reach large amplitude. The fluctuations in spacecraft potential follow the envelope function of the Langmuir and upper hybrid waves. Comparison with the high‐resolution electron moments shows that the changes in spacecraft potential associated with the waves are not due to density perturbations. Indeed, using the spacecraft potential as a density probe leads to unphysically large density fluctuations. In addition, the changes in spacecraft potential are shown to increase as density decreases: larger spacecraft potential changes are observed in the magnetosphere, than in the magnetosheath and solar wind. These results show that external electric fields can lead to unphysical results when the spacecraft potential is used as a density probe. The results suggest that fluctuations in the spacecraft potential alone cannot be used to determine whether nonlinear processes associated with Langmuir and upper hybrid waves, such as the ponderomotive force and three‐wave decay, are occurring.

show abstract

The Electron Drift Instrument for MMS

Cited by 22 publications

References 9 publications

Plasma Density Estimates From Spacecraft Potential Using MMS Observations in the Dayside Magnetosphere

Plasma Density Estimates From Spacecraft Potential Using MMS Observations in the Dayside Magnetosphere

Generation of Electron Whistler Waves at the Mirror Mode Magnetic Holes: MMS Observations and PIC Simulation

Enhanced Escape of Spacecraft Photoelectrons Caused by Langmuir and Upper Hybrid Waves

Contact Info

Product

Resources

About