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Detailed Reference Information |
Barbosa, D.D. (1993). Theory and observations of electromagnetic ion cyclotron waves in Saturn's inner magnetosphere. Journal of Geophysical Research 98: doi: 10.1029/93JA00476. issn: 0148-0227. |
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High-resolution Voyager 1 magnetic field observations of Saturn's inner magnetosphere are examined for the presence of ultralow frequency waves. Quasi-circular left-hand polarized transverse oscillations are found in the near-equatorial region of 5--7 RS with a wave period ~10 s and peak amplitude ~2 nT. The wave is identified as the electromagnetic oxygen cyclotron mode occurring at a frequency just below the O+ ion cyclotron frequency. The properties of the waves are very similar to those found by Smith and Tsurutani (1983) using Pioneer 11 data. A theoretical model of wave excitation based on gyroresonant coupling through a temperature anisotropy of O+ pickup ions is developed which accounts for the principal features of the wave spectrum. The theory and observations form the basis for the hypothesis that wave-particle interactions provide a level of scattering commensurate with the weak pitch angle diffusion regime but nonetheless one that regulates and maintains a constant thermal anisotropy of ions along the magnetic field. Arguments are also presented that O+ was the dominant thermal ion of the Dione-Tethys plasma torus at the time of the Pioneer 11 encounter the year previous to the Voyager 1 measurements. ¿ American Geophysical Union 1993 |
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Abstract |
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Keywords
Magnetospheric Physics, Planetary magnetospheres, Magnetospheric Physics, MHD waves and instabilities, Magnetospheric Physics, Magnetosphere interactions with satellites and rings, Magnetospheric Physics, Energetic particles, trapped |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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