Limits...
Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system.

Mauk BH - J Geophys Res Space Phys (2014)

Bottom Line: In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate.Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV.We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process.

View Article: PubMed Central - PubMed

Affiliation: Johns Hopkins University Applied Physics Laboratory Laurel, Maryland, USA.

ABSTRACT

Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes.

No MeSH data available.


Related in: MedlinePlus

(top) A replotting of the Jupiter energetic ion spectra shown in Figure1. (bottom) The Kennel-Petschek analysis of the Jupiter spectra, comprising the Cm/CK profiles derived using equation (4).
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fig07: (top) A replotting of the Jupiter energetic ion spectra shown in Figure1. (bottom) The Kennel-Petschek analysis of the Jupiter spectra, comprising the Cm/CK profiles derived using equation (4).

Mentions: Figure7 (bottom) shows the Kennel-Petschek analyses for the five Jupiter spectra shown in Figure1 (Figure7 (top) is a replot of the Jupiter spectra from Figure1). It would appear from these analyses that Jupiter's energetic ion populations are constrained by the classical Kennel-Petschek limit. Assuming that the Kennel-Petschek limit is playing the role ascribed to it here, the reason why Jupiter's ion populations would be constrained by the classical limit whereas Earth's ion populations are constrained by a somewhat higher level (factor of ∽3) is not known. However, these systems are very different and it would not be a surprise if one or more of the fundamental parameters (D, R, and S) were also different. It is of interest that the Cm/CK profiles from three out of four of the spectra obtained from the Galileo mission reach up to “contact” the Cm/CK = 1 line at various ranges of energy. It is only the Voyager spectrum, observed during the period of the inflated ring current epoch, that has a Cm/CK profile that lies flat against the Cm/CK = 1 line over an extended range of energies. That is also the Jupiter spectrum in Figure1 that is the flattest for energies below a break point near ∽2 MeV.


Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system.

Mauk BH - J Geophys Res Space Phys (2014)

(top) A replotting of the Jupiter energetic ion spectra shown in Figure1. (bottom) The Kennel-Petschek analysis of the Jupiter spectra, comprising the Cm/CK profiles derived using equation (4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4497457&req=5

fig07: (top) A replotting of the Jupiter energetic ion spectra shown in Figure1. (bottom) The Kennel-Petschek analysis of the Jupiter spectra, comprising the Cm/CK profiles derived using equation (4).
Mentions: Figure7 (bottom) shows the Kennel-Petschek analyses for the five Jupiter spectra shown in Figure1 (Figure7 (top) is a replot of the Jupiter spectra from Figure1). It would appear from these analyses that Jupiter's energetic ion populations are constrained by the classical Kennel-Petschek limit. Assuming that the Kennel-Petschek limit is playing the role ascribed to it here, the reason why Jupiter's ion populations would be constrained by the classical limit whereas Earth's ion populations are constrained by a somewhat higher level (factor of ∽3) is not known. However, these systems are very different and it would not be a surprise if one or more of the fundamental parameters (D, R, and S) were also different. It is of interest that the Cm/CK profiles from three out of four of the spectra obtained from the Galileo mission reach up to “contact” the Cm/CK = 1 line at various ranges of energy. It is only the Voyager spectrum, observed during the period of the inflated ring current epoch, that has a Cm/CK profile that lies flat against the Cm/CK = 1 line over an extended range of energies. That is also the Jupiter spectrum in Figure1 that is the flattest for energies below a break point near ∽2 MeV.

Bottom Line: In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate.Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV.We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process.

View Article: PubMed Central - PubMed

Affiliation: Johns Hopkins University Applied Physics Laboratory Laurel, Maryland, USA.

ABSTRACT

Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes.

No MeSH data available.


Related in: MedlinePlus