Peace: A Plasma Electron and Current Experiment

An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.

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“…2e). For this pass, the three other Cluster spacecraft have also observed this region with electron data 33 (Fig. 2b, and Supplementary Fig.…”

Section: Resultsmentioning

confidence: 57%

Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times

et al. 2013

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“…Substituting the observed values (v SW = 450 km/s, f p = 30 kHz, q = 50°), we obtain a beam energy of 200 eV or v b % 4 v Tc , which is significantly lower than a beam energy expected to excite such intense Langmuir waves [Bale et al, 2000]. During our event, the PEACE particle instrument [Johnstone et al, 1997] of Cluster was operating in a lowenergy mode, in which it registers only electrons with energies up to 2.6 keV. No beam-like features were observed in this low-energy part of the electron distribution at the same time intervals as the bursts of intense wave activity.…”

Section: Observationsmentioning

confidence: 51%

“…The density n c was estimated from the local plasma frequency, T c was inferred from PEACE [Johnstone et al, 1997] data. Average values obtained by previous observations [Maksimovic et al, 2000] are taken for the hot component properties T h and n h .…”

Section: Model and Interpretationmentioning

confidence: 99%

Nonlinear decay of foreshock Langmuir waves in the presence of plasma inhomogeneities: Theory and Cluster observations

et al. 2005

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[1] The intense high-frequency electrostatic waves observed in the terrestrial foreshock often have a form of a superposition of two monochromatic waves close to the plasma frequency. We suggest an interpretation of these spectra as signatures of nonlinear decay of Langmuir waves to electron-sound and ion-sound secondary waves. This decay instability is known to have different properties in inhomogeneous plasma, namely the threshold amplitude of this instability is inversely proportional to the scale of the inhomogeneity. We show that the observed dependence of the wave amplitude on the modulation scale of the wave packets is consistent with this property and the theory of absolute decay instability in inhomogeneous plasma can be applied to explain the satellite observations. In this study we used electric field data from the Wide Band Data instrument on board Cluster satellites.

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“…[16] The average pitch angle distribution of the electrons measured by the Cluster 1 (C1) PEACE instrument [Johnstone et al, 1997] is shown in Figure 4 for 9 September 2003 from 0112 to 0115 UT (same time interval as for the waves). (We showed wave data from C3.…”

Section: Observed Distribution Functionsmentioning

confidence: 99%

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

et al. 2010

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[1] Multiple-harmonic electromagnetic waves in the ULF band have occasionally been observed in Earth's magnetosphere, both near the magnetic equator in the outer plasmasphere and in the plasma sheet boundary layer (PSBL) in Earth's magnetotail. Observations by the Cluster spacecraft of multiple-harmonic electromagnetic waves with fundamental frequency near the local proton cyclotron frequency, W cp , were recently reported in the plasma sheet boundary layer by Broughton et al. (2008). A companion paper surveys the entire magnetotail passage of Cluster during 2003, and reports 35 such events, all in the PSBL, and all associated with elevated fluxes of counterstreaming ions and electrons. In this study we use observed pitch angle distributions of ions and electrons during a wave event observed by Cluster on 9 September 2003 to perform an instability analysis. We use a semiautomatic procedure for developing model distributions composed of bi-Maxwellian components that minimizes the difference between modeled and observed distribution functions. Analysis of wave instability using the WHAMP electromagnetic plasma wave dispersion code and these model distributions reveals an instability near W cp and its harmonics. The observed and model ion distributions exhibit both beam-like and ring-like features which might lead to instability. Further instability analysis with simple beam-like and ring-like model distribution functions indicates that the instability is due to the ring-like feature. Our analysis indicates that this instability persists over an enormous range in the effective ion beta (based on a best fit for the observed distribution function using a single Maxwellian distribution), b′, but that the character of the instability changes with b′. For b′ of order unity (for instance, the observed case with b′ ∼ 0.4), the instability is predominantly electromagnetic; the fluctuating magnetic field has components in both the perpendicular and parallel directions, but the perpendicular fluctuations are larger. If b′ is greatly decreased to about 5 × 10 −4 (by increasing the magnetic field), the instability becomes electrostatic. On the other hand, if b′ is increased (by decreasing the magnetic field), the instability remains electromagnetic, but becomes predominantly compressional (magnetic fluctuations predominantly parallel) at b′ ∼ 2. The b′ dependence we observe here may connect various waves at harmonics of the proton gyrofrequency found in different regions of space.

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Peace: A Plasma Electron and Current Experiment

Cited by 393 publications

References 12 publications

Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times

Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times

Nonlinear decay of foreshock Langmuir waves in the presence of plasma inhomogeneities: Theory and Cluster observations

Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

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