Journal article
Anisotropy and proton density in the Io plasma torus derived from whistler wave dispersion
Journal of geophysical research, Vol.101(A2), pp.2699-2706
02/01/1996
DOI: 10.1029/95JA02212
Abstract
During the Voyager 1 encounter with Jupiter, a large number of whistler waves were observed. Previous studies have examined the dispersion of these waves and made estimates of the electron and light ion (i.e., proton) densities. The current paper reexamines this data, taking into account the revised temperatures of the torus species the additional data on ion composition from the Voyager UVS instrument and the role of thermal anisotropy on the plasma densities. These refinements in the density model drastically alter the implications of the whistler wave data. Both the thermal and the nonthermal species must be anisotropic to fit the whistler dispersions. The thermal component must have T⊥/T‖ > 1.75 and the nonthermal component 3 < T⊥/T‖ < 10, The equatorial proton density is low, under 60 cm−3 in all cases. This results in a proton abundance (L shell proton content relative to the total ion content) of no more than 10%, approximately a factor of two lower than the conclusions of previous whistler analysis. At the high latitudes, the implied electron density results in a plasma frequency of under 20 kHz. Finally, it is evident from this analysis that not all of the whistler waves were propagating along the magnetic field lines, as was commonly assumed in previous work.
Details
- Title: Subtitle
- Anisotropy and proton density in the Io plasma torus derived from whistler wave dispersion
- Creators
- F. J Crary - Univ. Colorado, astrophysical planetary atmospheric sci. dep., Boulder CO 80309-0391, United StatesF Bagenal - Univ. Colorado, astrophysical planetary atmospheric sci. dep., Boulder CO 80309-0391, United StatesJ. A Ansher - Univ. Colorado, astrophysical planetary atmospheric sci. dep., Boulder CO 80309-0391, United StatesD. A Gurnett - University of Iowa, Physics and AstronomyW. S Kurth - University of Iowa, Physics and Astronomy
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research, Vol.101(A2), pp.2699-2706
- Publisher
- American Geophysical Union
- DOI
- 10.1029/95JA02212
- ISSN
- 0148-0227
- eISSN
- 2156-2202
- Language
- English
- Date published
- 02/01/1996
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455574602771
Metrics
2 Record Views