摘要:

Earthward propagation of substorm‐associated, abrupt plasma changes has been observed near synchronous orbit (Moore et al., 1981). We report data obtained from the University of New Hampshire hot plasma instrument on the ATS‐6 spacecraft during January 1980 that provide electron and ion pitch angle distributions in the vicinity of such an injection front. Evidence is found of symmetric atmospheric source cones for few 100‐eV electrons after front passage. This supports the concept of atmospheric electron degradation of the hot high altitude plasma, and the proposal that the injection front is a moving precipitation‐flow boundary between the hot plasma and the cooler plasma, which has become spectrally degraded via interaction with the atmosphere. In contrast, ion source cone distributions are more sporadic and not clearly associated with the injection front passage. The enhanced hot plasma electron intensities that appear in association with front passage exhibit a modest field‐aligned anisotropy with a minimum at 90° pitch angle and secondary minima at small and large pitch angles characteristic of symmetric loss cones. This is consistent with mirror compression of these electrons on inward‐collapsing field lines. Ions of comparable energies do not exhibit the field alignment, probably because their bounce periods are comparable to or longer than the time scale of collapse so that their second invariants are n

ISSN:0148-0227    

DOI:10.1029/JA087iA01p00265

年代:1982

数据来源: WILEY

摘要:

We present a unique set of wave and particle measurements taken by the S3‐3 satellite on August 2, 1976, from which we infer that signals from a ground‐based VLF transmitter were ducted up to the equatorial plasma sheet region by a detached region atL∼ 4.5. The waves resonated with the ∼ 1 keV plasma sheet electrons, producing narrowband emissions that were received in the conjugate hemisphere by the S3‐3 satelli

ISSN:0148-0227    

DOI:10.1029/JA087iA01p00271

年代:1982

数据来源: WILEY

摘要:

The characteristics of plasma flow are studied statistically by using the IMP 6 plasma and magnetic field data. The analysis was performed by dividing the data set according to flow direction and flow velocity. Fast tailward flows (those with a tailward component of velocity exceeding 300 km/s) are observed only within a few REof the estimated neutral sheet position and are associated with southward polarity of the magnetic field. They can therefore be interpreted as a product of reconnection operating at a location earthward of the spacecraft. On the other hand, slow tailward flows (those with a tailward component less than 300 km/s) are not associated with southward field polarity and are very similar to slow earthward flows (those with an anti‐tailward component less than 300 km/s) in such characteristics as association to northward inclination of the field and occurrence over a wide range of distance (± several RE) from the neutral sheet. These results suggest that there exist at least two source mechanisms of plasma flow in the magnetotail; X type neutral line in the near‐earth plasma sheet is likely to be the source of the fast tailward flows but other driving mechanisms are responsible for slow f

ISSN:0148-0227    

DOI:10.1029/JA087iA01p00277

年代:1982

数据来源: WILEY

ISSN:0148-0227    

DOI:10.1029/JA087iA01p00284

年代:1982

数据来源: WILEY