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Energetic Oxygen and Sulfur in the Jovian Magnetosphere

Gehrels, N. and Stone, E. C. and Trainor, J. H. (1981) Energetic Oxygen and Sulfur in the Jovian Magnetosphere. Journal of Geophysical Research A, 86 (A11). pp. 8906-8918. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20140206-101415588

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Abstract

This paper reports measurements made by the cosmic ray subsystem onboard Voyager 1 and 2 in the Jovian magnetosphere. Energy spectra of oxygen ions in the energy range 1–20 MeV/nuc between 5 and 20 R_J are presented and used to calculate phase space densities. There is a steep positive radial gradient in the phase space density of the energetic oxygen ions in this region, indicating an inward diffusive flow. Solutions of the diffusion equation assuming a diffusion coefficient D and loss lifetime τ of the forms D=D_0L^n and τ=τ_0L^m, where D_0, τ_0, n, and m are constants, and L is the McIlwain parameter, are fit to the radial phase space density profile of oxygen ions with magnetic moments of 680 MeV/nuc-G. The best fits are found to have n + m ≈ 6 and 3 <n <6. On the basis of the diffusion coefficient upper limit obtained from these fits, the upper limit on the rate at which oxygen ions with >400 MeV/nuc-G diffuse inward across 10 R_J is 5 × 10^(21±1) ions s^(−1). The observations suggest that oxygen and sulfur ions in the Io plasma torus diffuse radially outward, are nonadiabatically accelerated in some region outside 17 R_J and then diffuse inward and outward from the acceleration region.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/JA086iA11p08906DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/JA086iA11p08906/abstractPublisherArticle
ORCID:
AuthorORCID
Stone, E. C.0000-0002-2010-5462
Additional Information:© 1981 by the American Geophysical Union. Manuscript Accepted: 2 Jun 1981. Manuscript Received: 11 Mar 1981. We greatly appreciate the efforts of R. E. Vogt, both in his capacity as CRS Principal Investigator and as a colleague who has provided useful discussions. We are also grateful to the Caltech and Goddard groups who have supported this investigation, with special thanks to W. E. Althouse, M. F. Beazley, R. Burrell, W. R. Cook, and D. E. Stilwell. We also thank D. L. Chenette, A. C. Cummings, and T. L. Garrard for helpful discussions. Ness and his colleagues on the Voyager magnetometer team provided the magnetic field data used in this analysis, which we gratefully acknowledge. We are also grateful to A. W. Schardt for providing a special formatting of the magnetic field data and for useful discussions. We thank A. Eviatar for sharing with us new ideas about acceleration processes. Supported by NASA under NAS7-100, NGR 05-002-160, and NAGW-200. The Editor thanks T. G. Northrop and R. B. McKibben for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANAS7-100
NASANGR 05-002-160
NASANAGW-200
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1981-03
Issue or Number:A11
Record Number:CaltechAUTHORS:20140206-101415588
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140206-101415588
Official Citation:Gehrels, N., E. C. Stone, and J. H. Trainor (1981), Energetic oxygen and sulfur in the Jovian magnetosphere, J. Geophys. Res., 86(A11), 8906–8918, doi:10.1029/JA086iA11p08906.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43694
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Feb 2014 18:40
Last Modified:20 Feb 2020 14:33

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