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Science 1 June 1979:
Vol. 204. no. 4396, pp. 998 - 1003
DOI: 10.1126/science.204.4396.998
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Articles

Low-Energy Charged Particle Environment at Jupiter: A First Look

S. M. KRIMIGIS 1, T. P. ARMSTRONG 2, W. I. AXFORD 3, C. O. BOSTROM 4, C. Y. FAN 5, G. GLOECKLER 6, L. J. LANZEROTTI 7, E. P. KEATH 4, R. D. ZWICKL 4, J. F. CARBARY 4, and D. C. HAMILTON 8

1 Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20810
2 Department of Physics and Astronomy, University of Kansas, Lawrence 66044
3 Max-Planck Institute for Aeronomy, D-3411 Katlenburg-Lindau 3, West Germany
4 Applied Physics Laboratory, Johns Hopkins University
5 Department of Physics, University of Arizona, Tucson 85721
6 Department of Physics and Astronomy, University of Maryland, College Park 20742
7 Bell Telephone Laboratories, Murray Hill, New Jersey 07974
8 Department of Physics and Astronomy, University of Maryland

The low-energy charged particle instrument on Voyager was designed to measure the hot plasma (electron and ion energies gsim 15 and gsim 30 kiloelectron volts, respectively) component of the Jovian magnetosphere. Protons, heavier ions, and electrons at these energies were detected nearly a third of an astronomical unit before encounter with the planet. The hot plasma near the magnetosphere boundary is predominantly composed of protons, oxygen, and sulfur in comparable proportions and a nonthermal power-law tail; its temperature is about 3 x 108 K, density about 5 x 10–3 per cubic centimeter, and energy density comparable to that of the magnetic field. The plasma appears to be corotating throughout the magnetosphere; no hot plasma outflow, as suggested by planetary wind theories, is observed. The main constituents of the energetic particle population (gsim200 kiloelectron volts per nucleon) are protons, helium, oxygen, sulfur, and some sodium observed throughout the outer magnetosphere; it is probable that the sulfur, sodium, and possibly oxygen originate at 1o. Fluxes in the outbound trajectory appear to be enhancedfrom sim90° to sim130° longitude (System III). Consistent low-energy particle flux periodicities were not observed on the inbound trajectory; both 5-and 10-hour periodicities were observed on the outbound trajectory. Partial absorption of > 10 million electron volts electrons is observed in the vicinity of the Io flux tube.

Submitted on April 24, 1979


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
An Overview of Energetic Particle Measurements in the Jovian Magnetosphere with the EPAC Sensor on Ulysses.
E. Keppler, J. B. Blake, M. Franz, A. Korth, N. Krupp, J. J. Quenby, M. Witte, and J. Woch (1992)
Science 257, 1553-1557
   Abstract »    PDF »
The Magnetosphere of Uranus: Hot Plasma and Radiation Environment.
S. M. KRIMIGIS, T. P. ARMSTRONG, W. I. AXFORD, A. F. CHENG, G. GLOECKLER, D. C. HAMILTON, E. P. KEATH, L. J. LANZEROTTI, and B. H. MAUK (1986)
Science 233, 97-102
   Abstract »    PDF »
Erosion of Galilean Satellite Surfaces by Jovian Magnetosphere Particles.
R. E. Johnson, R. E. JOHNSON, L. J. LANZEROTTI, W. L. BROWN, and T. P. ARMSTRONG (1981)
Science 212, 1027-1030
   Abstract »    PDF »
Preliminary Results on the Plasma Environment of Saturn from the Pioneer 11 Plasma Analyzer Experiment.
J. H. WOLFE, J. D. MIHALOV, H. R. COLLARD, D. D. MCKIBBIN, L. A. FRANK, and D. S. INTRILIGATOR (1980)
Science 207, 403-407
   Abstract »    PDF »
Hot Plasma Environment at Jupiter: Voyager 2 Results.
S. M. KRIMIGIS, T. P. ARMSTRONG, W. I. AXFORD, C. O. BOSTROM, C. Y. FAN, G. GLOECKLER, L. J. LANZEROTTI, E. P. KEATH, R. D. ZWICKL, J. F. CARBARY, et al. (1979)
Science 206, 977-984
   Abstract »    PDF »
Voyager 2: Energetic Ions and Electrons in the Jovian Magnetosphere.
R. E. VOGT, A. C. CUMMINGS, T. L. GARRARD, N. GEHRELS, E. C. STONE, J. H. TRAINOR, A. W. SCHARDT, T. F. CONLON, and F. B. MCDONALD (1979)
Science 206, 984-987
   Abstract »    PDF »
Jupiter Plasma Wave Observations: An Initial Voyager 1 Overview.
F. L. SCARF, D. A. GURNETT, and W. S. KURTH (1979)
Science 204, 991-995
   Abstract »    PDF »
Voyager 1: Energetic Ions and Electrons in the Jovian Magnetosphere.
R. E. VOGT, W. R. COOK, A. C. CUMMINGS, T. L. GARRARD, N. GEHRELS, E. C. STONE, J. H. TRAINOR, A. W. SCHARDT, T. CONLON, N. LAL, et al. (1979)
Science 204, 1003-1007
   Abstract »    PDF »


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