Ogo 5 observations of LHR noise, emissions, and whistlers near the plasmapause at several Earth radii during a large magnetic storm

Scarf, F. L.; Fredericks, R. W.; Smith, E. J.; Frandsen, A. M. A.; Serbu, G. P.

doi:10.1029/ja077i010p01776

Cited by 17 publications

(4 citation statements)

References 29 publications

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“…This general idea is supported by the many observations showing an association between energetic electron precipitation and the presence of VLF noise (see, for example, Oliven and Gurnett [1968], Rosenberg et al [197lb], and Holzer et al [1974]; for recent reviews, see, for example, Fredricks [1975], Gendrin [1975], and Barfield[1975]). Both electromagnetic waves [Burtis and Dunckel and Helliwell, 1969;Burton and Holzer, 1974;Smith, 1974, 1977;Burtis and Helliwell, 1976] and electrostatic waves [Kennel et al, 1970;Scarf et al, 1972] are found in the magnetosphere. Both of these wave types can scatter energetic electrons efficiently [Koons et al, 1972;Lyons, 1974].…”

Section: Introductionmentioning

confidence: 99%

Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

Trefall

Williams²

1979

J. Geophys. Res.

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High time‐resolution measurements of trapped and precipitated >30‐keV electrons from the low‐altitude polar‐orbiting satellite Ogo 6 in the postmidnight‐to‐dayside region of the auroral zone are presented. It is found that precipitation usually occurs in brief bursts of a few seconds duration or less, with normally a very abrupt transition between no precipitation and isotropic (full loss cone) precipitation. Thus if pitch angle scattering is the precipitation mechanism, it seems to be either very strong or nearly nonexistent, and intermediate‐strength pitch angle scattering modes do not usually seem to represent a stable precipitation regime in this part of the auroral zone. Sustained precipitation in time and/or space is found only at very high flux levels, whilst the duration as well as the frequency of the burstlike precipitation events observed at lower flux levels apparently decreases with decreasing flux of trapped electrons. This is consistent with theories which predict the existence of a critical flux level at which the electron population becomes unstable and strong pitch angle scattering takes place, though there remains the question of how the burstlike precipitation is generated. The action of a delayed negative feedback mechanism is suggested. The burstlike character of the precipitation is of great importance for the average lifetime of electrons drifting in the geomagnetic field, as it reduces the average loss rate to a level which obviates the need for any additional acceleration in the morning‐to‐dayside region to explain the ability of such electrons to gradient drift most of the way around the auroral zone.

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Section: Introductionmentioning

confidence: 99%

Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

Trefall

Williams²

1979

J. Geophys. Res.

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“…Measurements at higher frequencies require higher time resolution in the experimental data which, among the techniques described earlier, has been achieved only for double probe potential difference measurements on rockets and satellites. Such experiments have been performed on more than 15 rockets [121,122,123,124,125,126,127,128,129] and 15 satellites in the ionosphere, magnetosphere, and interplanetary medium [130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148] over a frequency range that has generally been ~ 10 to ~ 105 Hz. Indirect measurements of the electric fields in waves can be made over a similar frequency range by other techniques.…”

Section: Introductionmentioning

confidence: 99%

Analyses of techniques for measuring DC and AC electric fields in the magnetosphere

Mozer

1973

Space Sci Rev

112

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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.

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“…to the ULF signals. Moreover, near 1219 UT the peak electric-field wave intensity was somewhat below 1 kHz, and the signal was attenuated by the internal plasma-wave filter), but it does show the 'LHR breakup' that has frequently been detected near the plasmapause [Carpenter et al, 1968;Scarf et al, 1972a]. Thus as late as 12h 19m 13s UT, the VLF electric-field instrument on Ogo 5 did not find unusual kinds of signals in the range from I to 22 kHz.…”

Section: Lowmentioning

confidence: 99%

“…The results are discussed and summarized in the final section. Paper 2 of this series [Scarf et al, 1972b] contains an analysis of the magnetopause and magnetosheath observations, emphasing the detection of some form of shock within the sheath above the cusp.…”

mentioning

confidence: 99%

Plasma waves in the dayside polar cusp: 1, Magnetospheric observations

Scarf¹,

Fredricks²,

Green³

et al. 1972

J. Geophys. Res.

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We present a general survey of the Ogo 5 plasma‐wave measurements for the dayside polar‐cusp encounters of November 1, 1968, and a detailed analysis of the observations at the low‐altitude (r ≃ 3–5 RE) cusp boundaries. The survey section contains an over‐all discussion of the ULF magnetic‐field wave levels and the VLF electric‐field amplitude ranges measured from perigee out to 9 RE on November 1, 1968. These cusp‐associated observations are compared with those made on October 27 and November 6, 1968, when Ogo 5 traversed the dayside magnetosphere without encountering the cusp. At the November 1 low‐altitude cusp boundaries, we show that intense wave levels were detected over a broad spectral region at the steep gradients in cusp plasma density and thermal energy. The results are interpreted in terms of drift instabilities for low‐β plasmas with hot ions, and associated wave‐particle and wave‐wave interactions are briefly discussed.

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Ogo 5 observations of LHR noise, emissions, and whistlers near the plasmapause at several Earth radii during a large magnetic storm

Cited by 17 publications

References 29 publications

Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

Analyses of techniques for measuring DC and AC electric fields in the magnetosphere

Plasma waves in the dayside polar cusp: 1, Magnetospheric observations

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