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Electron sources in Saturn's magnetosphere
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| Zeitschriftentitel: | Journal of Geophysical Research: Space Physics |
|---|---|
| Personen und Körperschaften: | , , , , , , , , , , , , , |
| In: | Journal of Geophysical Research: Space Physics, 112, 2007, A2 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Geophysical Union (AGU)
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| Schlagwörter: |
| author_facet |
Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. |
|---|---|
| author |
Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. |
| spellingShingle |
Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. Journal of Geophysical Research: Space Physics Electron sources in Saturn's magnetosphere Paleontology Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Earth-Surface Processes Geochemistry and Petrology Soil Science Water Science and Technology Ecology Aquatic Science Forestry Oceanography Geophysics |
| author_sort |
rymer, a. m. |
| spelling |
Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. 0148-0227 American Geophysical Union (AGU) Paleontology Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Earth-Surface Processes Geochemistry and Petrology Soil Science Water Science and Technology Ecology Aquatic Science Forestry Oceanography Geophysics http://dx.doi.org/10.1029/2006ja012017 <jats:p>We investigate the sources of two different electron components in Saturn's inner magnetosphere (5 < <jats:italic>L</jats:italic> < 12 Rs) by performing phase space density (<jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>)) analyses of electron measurements made by the Cassini CAPS instrument (1 eV to 28 keV). Because pitch angle distributions indicate that the traditional single particle invariants of gyration and bounce are not appropriate, we use a formulation of the isotropic invariant derived by Wolf (1983) and Schulz (1998) and show that it is similar in functional form to the first adiabatic invariant. Our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses confirm that the cooler electrons (<100 eV) have a source in the inner magnetosphere and are likely products of neutral ionization processes in Saturn's neutral cloud. The mystery is how the electrons are heated to energies comparable to the proton thermal energy (which is approximately equal to the proton pickup energy), a process that reveals itself as a source of electrons at given invariant values in our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses. We show that Coulomb collisions provide a viable mechanism to achieve the near equipartition of ion and electron energies in the time available before particles are lost from the region. We find that the source of the hotter electron component (>100 eV) is Saturn's middle or outer magnetosphere, perhaps transported to the inner magnetosphere by radial diffusion regulated by interchange‐like injections. Hot electrons undergo heavy losses inside <jats:italic>L</jats:italic> ∼ 6 and the distance to which the hot electron component penetrates into the neutral cloud is energy‐dependent, with the coolest fraction of the hot plasma penetrating to the lowest <jats:italic>L</jats:italic>‐shells. This can arise through energy‐dependent radial transport during the interchange process and/or loss through the planetary loss cone.</jats:p> Electron sources in Saturn's magnetosphere Journal of Geophysical Research: Space Physics |
| doi_str_mv |
10.1029/2006ja012017 |
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Online Free |
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Geographie Chemie und Pharmazie Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft Biologie Allgemeine Naturwissenschaft Physik Technik Geologie und Paläontologie |
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| title |
Electron sources in Saturn's magnetosphere |
| title_unstemmed |
Electron sources in Saturn's magnetosphere |
| title_full |
Electron sources in Saturn's magnetosphere |
| title_fullStr |
Electron sources in Saturn's magnetosphere |
| title_full_unstemmed |
Electron sources in Saturn's magnetosphere |
| title_short |
Electron sources in Saturn's magnetosphere |
| title_sort |
electron sources in saturn's magnetosphere |
| topic |
Paleontology Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Earth-Surface Processes Geochemistry and Petrology Soil Science Water Science and Technology Ecology Aquatic Science Forestry Oceanography Geophysics |
| url |
http://dx.doi.org/10.1029/2006ja012017 |
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2007 |
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<jats:p>We investigate the sources of two different electron components in Saturn's inner magnetosphere (5 < <jats:italic>L</jats:italic> < 12 Rs) by performing phase space density (<jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>)) analyses of electron measurements made by the Cassini CAPS instrument (1 eV to 28 keV). Because pitch angle distributions indicate that the traditional single particle invariants of gyration and bounce are not appropriate, we use a formulation of the isotropic invariant derived by Wolf (1983) and Schulz (1998) and show that it is similar in functional form to the first adiabatic invariant. Our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses confirm that the cooler electrons (<100 eV) have a source in the inner magnetosphere and are likely products of neutral ionization processes in Saturn's neutral cloud. The mystery is how the electrons are heated to energies comparable to the proton thermal energy (which is approximately equal to the proton pickup energy), a process that reveals itself as a source of electrons at given invariant values in our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses. We show that Coulomb collisions provide a viable mechanism to achieve the near equipartition of ion and electron energies in the time available before particles are lost from the region. We find that the source of the hotter electron component (>100 eV) is Saturn's middle or outer magnetosphere, perhaps transported to the inner magnetosphere by radial diffusion regulated by interchange‐like injections. Hot electrons undergo heavy losses inside <jats:italic>L</jats:italic> ∼ 6 and the distance to which the hot electron component penetrates into the neutral cloud is energy‐dependent, with the coolest fraction of the hot plasma penetrating to the lowest <jats:italic>L</jats:italic>‐shells. This can arise through energy‐dependent radial transport during the interchange process and/or loss through the planetary loss cone.</jats:p> |
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| author | Rymer, A. M., Mauk, B. H., Hill, T. W., Paranicas, C., André, N., Sittler, E. C., Mitchell, D. G., Smith, H. T., Johnson, R. E., Coates, A. J., Young, D. T., Bolton, S. J., Thomsen, M. F., Dougherty, M. K. |
| author_facet | Rymer, A. M., Mauk, B. H., Hill, T. W., Paranicas, C., André, N., Sittler, E. C., Mitchell, D. G., Smith, H. T., Johnson, R. E., Coates, A. J., Young, D. T., Bolton, S. J., Thomsen, M. F., Dougherty, M. K., Rymer, A. M., Mauk, B. H., Hill, T. W., Paranicas, C., André, N., Sittler, E. C., Mitchell, D. G., Smith, H. T., Johnson, R. E., Coates, A. J., Young, D. T., Bolton, S. J., Thomsen, M. F., Dougherty, M. K. |
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| description | <jats:p>We investigate the sources of two different electron components in Saturn's inner magnetosphere (5 < <jats:italic>L</jats:italic> < 12 Rs) by performing phase space density (<jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>)) analyses of electron measurements made by the Cassini CAPS instrument (1 eV to 28 keV). Because pitch angle distributions indicate that the traditional single particle invariants of gyration and bounce are not appropriate, we use a formulation of the isotropic invariant derived by Wolf (1983) and Schulz (1998) and show that it is similar in functional form to the first adiabatic invariant. Our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses confirm that the cooler electrons (<100 eV) have a source in the inner magnetosphere and are likely products of neutral ionization processes in Saturn's neutral cloud. The mystery is how the electrons are heated to energies comparable to the proton thermal energy (which is approximately equal to the proton pickup energy), a process that reveals itself as a source of electrons at given invariant values in our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses. We show that Coulomb collisions provide a viable mechanism to achieve the near equipartition of ion and electron energies in the time available before particles are lost from the region. We find that the source of the hotter electron component (>100 eV) is Saturn's middle or outer magnetosphere, perhaps transported to the inner magnetosphere by radial diffusion regulated by interchange‐like injections. Hot electrons undergo heavy losses inside <jats:italic>L</jats:italic> ∼ 6 and the distance to which the hot electron component penetrates into the neutral cloud is energy‐dependent, with the coolest fraction of the hot plasma penetrating to the lowest <jats:italic>L</jats:italic>‐shells. This can arise through energy‐dependent radial transport during the interchange process and/or loss through the planetary loss cone.</jats:p> |
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| spelling | Rymer, A. M. Mauk, B. H. Hill, T. W. Paranicas, C. André, N. Sittler, E. C. Mitchell, D. G. Smith, H. T. Johnson, R. E. Coates, A. J. Young, D. T. Bolton, S. J. Thomsen, M. F. Dougherty, M. K. 0148-0227 American Geophysical Union (AGU) Paleontology Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Earth-Surface Processes Geochemistry and Petrology Soil Science Water Science and Technology Ecology Aquatic Science Forestry Oceanography Geophysics http://dx.doi.org/10.1029/2006ja012017 <jats:p>We investigate the sources of two different electron components in Saturn's inner magnetosphere (5 < <jats:italic>L</jats:italic> < 12 Rs) by performing phase space density (<jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>)) analyses of electron measurements made by the Cassini CAPS instrument (1 eV to 28 keV). Because pitch angle distributions indicate that the traditional single particle invariants of gyration and bounce are not appropriate, we use a formulation of the isotropic invariant derived by Wolf (1983) and Schulz (1998) and show that it is similar in functional form to the first adiabatic invariant. Our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses confirm that the cooler electrons (<100 eV) have a source in the inner magnetosphere and are likely products of neutral ionization processes in Saturn's neutral cloud. The mystery is how the electrons are heated to energies comparable to the proton thermal energy (which is approximately equal to the proton pickup energy), a process that reveals itself as a source of electrons at given invariant values in our <jats:italic>f</jats:italic>(<jats:italic>v</jats:italic>) analyses. We show that Coulomb collisions provide a viable mechanism to achieve the near equipartition of ion and electron energies in the time available before particles are lost from the region. We find that the source of the hotter electron component (>100 eV) is Saturn's middle or outer magnetosphere, perhaps transported to the inner magnetosphere by radial diffusion regulated by interchange‐like injections. Hot electrons undergo heavy losses inside <jats:italic>L</jats:italic> ∼ 6 and the distance to which the hot electron component penetrates into the neutral cloud is energy‐dependent, with the coolest fraction of the hot plasma penetrating to the lowest <jats:italic>L</jats:italic>‐shells. This can arise through energy‐dependent radial transport during the interchange process and/or loss through the planetary loss cone.</jats:p> Electron sources in Saturn's magnetosphere Journal of Geophysical Research: Space Physics |
| spellingShingle | Rymer, A. M., Mauk, B. H., Hill, T. W., Paranicas, C., André, N., Sittler, E. C., Mitchell, D. G., Smith, H. T., Johnson, R. E., Coates, A. J., Young, D. T., Bolton, S. J., Thomsen, M. F., Dougherty, M. K., Journal of Geophysical Research: Space Physics, Electron sources in Saturn's magnetosphere, Paleontology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Earth-Surface Processes, Geochemistry and Petrology, Soil Science, Water Science and Technology, Ecology, Aquatic Science, Forestry, Oceanography, Geophysics |
| title | Electron sources in Saturn's magnetosphere |
| title_full | Electron sources in Saturn's magnetosphere |
| title_fullStr | Electron sources in Saturn's magnetosphere |
| title_full_unstemmed | Electron sources in Saturn's magnetosphere |
| title_short | Electron sources in Saturn's magnetosphere |
| title_sort | electron sources in saturn's magnetosphere |
| title_unstemmed | Electron sources in Saturn's magnetosphere |
| topic | Paleontology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Earth-Surface Processes, Geochemistry and Petrology, Soil Science, Water Science and Technology, Ecology, Aquatic Science, Forestry, Oceanography, Geophysics |
| url | http://dx.doi.org/10.1029/2006ja012017 |