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  • 1
    Electronic Resource
    Electronic Resource
    Balloon measurement of vertical and horizontal atmospheric electric fields (1971)
    Springer
    Pure and applied geophysics 84 (1971), S. 32-45 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Twenty-eight balloons have been flown in Canada to measure vertical and horizontal electric fields at balloon altitudes. A horizontal electric field of magnitude typically between 10 and 50 millivolts/meter has been measured at night at high latitudes in association with auroras and magnetic disturbances. Its origin is in the magnetosphere and it maps to balloon alitudes with small attenuation according to Maxwell's equations. The vertical electric field at the balloon displays variations as the horizontal ionospheric field changes in order to maintain $$\bar \nabla \dot x\bar E = 0$$ . Thus, magnetospheric processes affect both vertical and horizontal atmospheric electric fields and the potential differences induced by these processes may be comparable to weather induced potential differences. Weather processes have also been observed to produce large horizontal electric fields at balloon altitudes. Methods of distinguishing horizontal fields of ionospheric origin from those of weather origin are investigated with the conclusion that a determination of the source of a given event can often if not generally be made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00875450
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  • 2
    Electronic Resource
    Electronic Resource
    How does the U-shaped potential close above the acceleration region? A study using Polar data (1999)
    Springer
    Annales geophysicae 17 (1999), S. 1276-1283 
    Details
    ISSN: 0992-7689
    Keywords: Ionosphere (particle acceleration) ; Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We present a statistical study of Polar electric field observations using auroral oval passes over Scandinavia above the acceleration region. We are especially interested in seeing whether we can find large perpendicular electric fields associated with an upward extended classical U-shaped potential drop for these passes, during which Polar is in the northern hemisphere usually at about 4 RE altitude. We also use Polar magnetic field data to infer the existence of a field-aligned current (FAC) and conjugate ground-based magnetometers (the IMAGE magnetometer network) to check whether the event is substorm-related or not. We find several events with a FAC but only weak perpendicular electric fields at Polar. In those rare cases where the Polar electric field was large, its direction was mostly found to be incompatible with the U-shaped potential model, or it was associated with disturbed conditions (substorms), where one cannot easily distinguish between inductive and static perpendicular electric fields. We found only two cases which are compatible with the upward extended U-shaped potential picture, and even in those cases the potential value is quite small (1–kV). To check the validity of the analysis method we also estimate the perpendicular electric field on the southern hemisphere, where Polar flies within or below the acceleration region, and we found a large number of inverted-V-type signatures as expected from previous studies. To explain the lack of perpendicular electric fields at high altitudes we suggest an O-shaped potential model instead of the U-shaped one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-1276-x
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  • 3
    Electronic Resource
    Electronic Resource
    THE ELECTRIC FIELD AND WAVE EXPERIMENT FOR THE CLUSTER MISSION (1997)
    Springer
    Space science reviews 79 (1997), S. 137-156 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36000 samples s-1. Langmuir probe sweeps can also be made to determine the electron density and temperature. The instrument has several important capabilities. These include (1) measurements of quasi-static electric fields of amplitudes up to 700 mV m-1 with high amplitude and time resolution, (2) measurements over short periods of time of up to five simualtaneous waveforms (two electric signals and three magnetic signals from the seach coil magnetometer sensors) of a bandwidth of 4 kHz with high time resolution, (3) measurements of density fluctuations in four points with high time resolution. Among the more interesting scientific objectives of the experiment are studies of nonlinear wave phenomena that result in acceleration of plasma as well as large- and small-scale interferometric measurements. By using four spacecraft for large-scale differential measurements and several Langmuir probes on one spacecraft for small-scale interferometry, it will be possible to study motion and shape of plasma structures on a wide range of spatial and temporal scales. This paper describes the primary scientific objectives of the EFW experiment and the technical capabilities of the instrument.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004975108657
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  • 4
    Electronic Resource
    Electronic Resource
    The double probe electric field experiment on Freja: Experiment description and first results (1994)
    Springer
    Space science reviews 70 (1994), S. 483-508 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A description is given of theFreja double-probe electric field instrument. Its capability to perform high-resolution measurements of the aurora and its fine-structure as well as collect information on sub-auroral and low-latitude phenomena is illustrated by selected results from the first six months of operation. The instrument is highly flexible and possible to operate in a number of different modes. It is also equipped with a 4-Megabyte burst memory for high data sampling rate and temporary storage of data. It has been fully operational since October 1992, and delivers data from ≈22 hr day−1 including about 5–6 auroral crossings of the northern and southern auroral ionosphere. New and important information on the auroral fine structure and electrodynamics is obtained by means of burst resolution data (6144 samples s−1) and normal resolution data (768 samples s−1). Common burst data collection triggered by the electric field event detector has turned out to be very useful for the selection of scientifically interesting events. This is illustrated by high-resolution data of a pair of extremely intense and narrow electric field structures (1 V m−1) which are associated with a total absence of precipitating particles, depletions of the thermal plasma and with an intense wave activity. The low inclination of theFreja orbit provides a new perspective for studying largescale phenomena associated with east-west gradients as is exemplified by electric field data from a satellite crossing over north-south oriented auroral structures presumably resulting from rotational distortions of east-west aligned auroral arcs. The different plasma regimes encountered byFreja are continuously monitored by means of current sweeps applied to the probes and by the satellite potential. In addition, overview data (8 samples s−1) are collected from full orbits and stored in the on-board memory and have proved to be extremely valuable, providing new information on global electric field phenomena at subauroral and lower latitudes, such as the intense poleward electric fields and Pc-1 observations that have been made near the plasmapause during substorm activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00756883
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  • 5
    Electronic Resource
    Electronic Resource
    The electric field instrument on the polar satellite (1995)
    Springer
    Space science reviews 71 (1995), S. 583-596 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Polar satellite carries a system of four wire booms in the spacecraft spin plane and two rigid booms along the spin axis. Each of the booms has a spherical sensor at its tip along with nearby guard and stub surfaces whose potentials relative to that of their sphere are controlled by associated electronics. The potential differences between opposite sphere pairs are measured to yield the three components of the DC to 〉1 MHz electric field. Spheres can also be operated in a mode in which their collected current is measured to give information on the plasma density and its fluctuations. The scientific studies to be performed by this experiment as well as the mechanical and electrical properties of the detector system are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751342
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  • 6
    Electronic Resource
    Electronic Resource
    Analyses of techniques for measuring DC and AC electric fields in the magnetosphere (1973)
    Springer
    Space science reviews 14 (1973), S. 272-313 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Methods for measuring the amplitudes and directions of DC electric fields and the directions, power spectra, and dispersion relations of AC electric fields in the magnetosphere are discussed with emphasis on their applicability in various regimes of the magnetospheric plasma. The two classes of techniques that are discussed are measurement of the bulk flow of the plasma and the potential difference between pairs of separated conductors. The plasma bulk flow discussion includes measurements by ionospheric radar backscatter, whistler mode wave propagation, energetic or thermal particle trajectories, artificial ion cloud motion, probe measurements of bulk flow, vehicle wake analyses, effects of bulk flow on the coupling of antennas, and the bulk flow of an artificial electron beam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02432099
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  • 7
    Electronic Resource
    Electronic Resource
    Large electric fields in the magnetosphere (1985)
    Springer
    Space science reviews 42 (1985), S. 313-335 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In several regions of the magnetosphere, perpendicular and/or parallel electric fields are found to be orders-of-magnitude larger than expected from simple considerations. Problems associated with these large fields that may be amenable to study through computer simulations are discussed. Regions in which large electric fields are observed include: a) The auroral ionosphere, where Langmuir soliton-like structures have been measured to contain plasma frequency oscillations as large as 500 mV/m, the envelopes of which have parallel electric fields of ∼100 mV/m lasting for fractions of a millisecond; b) The auroral acceleration region, where electrostatic shocks have been observed to contain perpendicular fields as large as 1000 mV/m and parallel fields as large as 100 mV/m, and where double layers having parallel fields up to 10 mV/m have been observed; c) The high latitude boundary of the plasma sheet, where turbulent electric fields as large as 100 mV/m have been seen along with quasi-static fields of 5–10 mV/m; d) Inside the plasma sheet, where fields of 5–10 mV/m have frequently been observed; e) The bow shock, where turbulent fields as large as 100 mV/m and d.c. fields of ∼5 mV/m normal to the shock have been seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214991
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  • 8
    Electronic Resource
    Electronic Resource
    Satellite measurements and theories of low altitude auroral particle acceleration (1980)
    Springer
    Space science reviews 27 (1980), S. 155-213 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Several previous and new S3-3 satellite results on DC electric fields, field-aligned currents, and waves are described, interpreted theoretically, and applied to the understanding of auroral particle acceleration at altitudes below 8000 km. These results include the existence of two spatial scale sizes (less than 0.1 degree and a few degrees invariant latitude) in both the perpendicular and parallel electric fields; the predominance of S-shaped rather than V-shaped equipotential contours on both spatial saales; the correlated presence of field-aligned currents, low frequency wave turbulence, coherent ion cyclotron wave emissions and accelerated upmoving ions and downgoing electrons; intense waves inside electrostatic shocks and important wave-particle interactions therein; correlations of field-aligned currents with magnetospheric boundaries that are determined by convection electric field measurements; electron acceleration producing discrete auroral arcs in the smaller scale fields and producing inverted-V events in the larger scale fields; ion and electron acceleration due to both wave-particle interactions and the parallel electric fields. Further analyses of acceleration mechanisms and energetics are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212238
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  • 9
    Electronic Resource
    Electronic Resource
    Electric field measurements in the solar wind, bow shock, magnetosheath, magnetopause, and magnetosphere (1978)
    Springer
    Space science reviews 22 (1978), S. 791-804 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electric field measurements are reported at 11 magnetopause crossings that occurred during a single in-bound ISEE-1 satellite pass near a local time of 10∶30. In combination with magnetic field data, these measurements show the existence of electric field components tangential to the actual magnetopause in the frame of rest of the magnetopause on every crossing of the current carrying layers associated with the 11 magnetopause traversals. These tangential electric field components were oriented with respect to the magnetopause sheet currents such that there was an electrical power dissipation of between 30 and 110 W km-2 on 10 of the 11 crossings. These results are in agreement with requirements of reconnection theories. Histograms of the normal electric field components and of the orientation, velocity, and thickness of the current carrying layer are presented. Suggestions of the existence of a parallel electric field in the magnetosheath near the magnetopause and of propagation of large amplitude waves along the magnetopause are also made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212624
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  • 10
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    Elastic Scattering of Protons byN14 (1957)
    American Physical Society
    Details
    Publication Date: 1957-01-01
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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