Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength
Isolated electrostatic structures are observed throughout much of the 4<i>R<sub>E</sub></i> by 19.6<i>R<sub>E</sub></i> Cluster orbit. These structures are observed in the Wideband plasma wave instrument's waveform data as bipolar pulses (one p...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2004-07-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/22/2515/2004/angeo-22-2515-2004.pdf |
| _version_ | 1818132809380790272 |
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| author | J. S. Pickett L.-J. Chen S. W. Kahler O. Santolík O. Santolík D. A. Gurnett B. T. Tsurutani A. Balogh |
| author_facet | J. S. Pickett L.-J. Chen S. W. Kahler O. Santolík O. Santolík D. A. Gurnett B. T. Tsurutani A. Balogh |
| author_sort | J. S. Pickett |
| collection | DOAJ |
| description | Isolated electrostatic structures are observed throughout
much of the 4<i>R<sub>E</sub></i> by 19.6<i>R<sub>E</sub></i> Cluster orbit. These structures are
observed in the Wideband plasma wave instrument's waveform data as bipolar
pulses (one positive and one negative peak in the electric field amplitude)
and tripolar pulses (two positive and one negative peak, or vice versa).
These structures are observed at all of the boundary layers, in the solar
wind and magnetosheath, and along auroral field lines at
4.5-6.5<i>R<sub>E</sub></i>.
Using the Wideband waveform data from the various Cluster spacecraft we have
carried out a survey of the amplitudes and time durations of these structures
and how these quantities vary with the local magnetic field strength. Such a
survey has not been carried out before, and it reveals certain
characteristics of solitary structures in a finite magnetic field, a topic
still inadequately addressed by theories. We find that there is a broad range
of electric field amplitudes at any specific magnetic field strength, and
there is a general trend for the electric field amplitudes to increase as the
strength of the magnetic field increases over a range of 5 to 500nT. We
provide a possible explanation for this trend that relates to the structures
being Bernstein-Greene-Kruskal mode solitary waves. There is no corresponding
dependence of the duration of the structures on the magnetic field strength,
although a plot of these two quantities reveals the unexpected result that
with the exception of the magnetosheath, all of the time durations for all of
the other regions are comparable, whereas the magnetosheath time durations
clearly are in a different category of much smaller time duration. We
speculate that this implies that the structures are much smaller in size. The
distinctly different pulse durations for the magnetosheath pulses indicate
the possibility that the pulses are generated by a mechanism which is
different from the mechanism operating in other regions. |
| first_indexed | 2024-12-11T08:42:44Z |
| format | Article |
| id | doaj.art-13758fd91f234b8e926474050d67032f |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-11T08:42:44Z |
| publishDate | 2004-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-13758fd91f234b8e926474050d67032f2022-12-22T01:14:12ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762004-07-01222515252310.5194/angeo-22-2515-2004Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strengthJ. S. Pickett0L.-J. Chen1S. W. Kahler2O. Santolík3O. Santolík4D. A. Gurnett5B. T. Tsurutani6A. Balogh7Department of Physics and Astronomy, The University of Iowa, Iowa City, IA, USADepartment of Physics and Astronomy, The University of Iowa, Iowa City, IA, USADepartment of Physics and Astronomy, The University of Iowa, Iowa City, IA, USADepartment of Physics and Astronomy, The University of Iowa, Iowa City, IA, USAFaculty of Mathematics and Physics, Charles University, Prague, Czech RepublicDepartment of Physics and Astronomy, The University of Iowa, Iowa City, IA, USAJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USAThe Blackett Laboratory, Imperial College, London, UKIsolated electrostatic structures are observed throughout much of the 4<i>R<sub>E</sub></i> by 19.6<i>R<sub>E</sub></i> Cluster orbit. These structures are observed in the Wideband plasma wave instrument's waveform data as bipolar pulses (one positive and one negative peak in the electric field amplitude) and tripolar pulses (two positive and one negative peak, or vice versa). These structures are observed at all of the boundary layers, in the solar wind and magnetosheath, and along auroral field lines at 4.5-6.5<i>R<sub>E</sub></i>. Using the Wideband waveform data from the various Cluster spacecraft we have carried out a survey of the amplitudes and time durations of these structures and how these quantities vary with the local magnetic field strength. Such a survey has not been carried out before, and it reveals certain characteristics of solitary structures in a finite magnetic field, a topic still inadequately addressed by theories. We find that there is a broad range of electric field amplitudes at any specific magnetic field strength, and there is a general trend for the electric field amplitudes to increase as the strength of the magnetic field increases over a range of 5 to 500nT. We provide a possible explanation for this trend that relates to the structures being Bernstein-Greene-Kruskal mode solitary waves. There is no corresponding dependence of the duration of the structures on the magnetic field strength, although a plot of these two quantities reveals the unexpected result that with the exception of the magnetosheath, all of the time durations for all of the other regions are comparable, whereas the magnetosheath time durations clearly are in a different category of much smaller time duration. We speculate that this implies that the structures are much smaller in size. The distinctly different pulse durations for the magnetosheath pulses indicate the possibility that the pulses are generated by a mechanism which is different from the mechanism operating in other regions.https://www.ann-geophys.net/22/2515/2004/angeo-22-2515-2004.pdf |
| spellingShingle | J. S. Pickett L.-J. Chen S. W. Kahler O. Santolík O. Santolík D. A. Gurnett B. T. Tsurutani A. Balogh Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength Annales Geophysicae |
| title | Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength |
| title_full | Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength |
| title_fullStr | Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength |
| title_full_unstemmed | Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength |
| title_short | Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength |
| title_sort | isolated electrostatic structures observed throughout the cluster orbit relationship to magnetic field strength |
| url | https://www.ann-geophys.net/22/2515/2004/angeo-22-2515-2004.pdf |
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