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    Particle pressure, inertial force, and ring current density profiles in the magnetosphere of Saturn, based on Cassini measurements

    Sergis, N. and Krimigis, S.M. and Roelof, E.C. and Arridge, Chris S. and Rymer, A.M. and Mitchell, D.G. and Hamilton, D.C. and Krupp, N. and Thomsen, M.F. and Dougherty, M.K. and Coates, Andrew J. and Young, D.T. (2010) Particle pressure, inertial force, and ring current density profiles in the magnetosphere of Saturn, based on Cassini measurements. Geophysical Research Letters 37 (2), ISSN 0094-8276.

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    Abstract

    We report initial results on the particle pressure distribution and its contribution to ring current density in the equatorial magnetosphere of Saturn, as measured by the Magnetospheric Imaging Instrument (MIMI) and the Cassini Plasma Spectrometer (CAPS) onboard the Cassini spacecraft. Data were obtained from September 2005 to May 2006, within ±0.5 RS from the nominal magnetic equator in the range 6 to 15 RS. The analysis of particle and magnetic field measurements, the latter provided by the Cassini magnetometer (MAG), allows the calculation of average radial profiles for various pressure components in Saturn's magnetosphere. The radial gradient of the total particle pressure is compared to the inertial body force to determine their relative contribution to the Saturnian ring current, and an average radial profile of the azimuthal current intensity is deduced. The results show that: (1) Thermal pressure dominates from 6 to 9 RS, while thermal and suprathermal pressures are comparable outside 9 RS with the latter becoming larger outside 12 RS. (2) The plasma β (particle/magnetic pressure) remains ≥1 outside 8 RS, maximizing (∼3 to ∼10) between 11 and 14 RS. (3) The inertial body force and the pressure gradient are similar at 9–10 RS, but the gradient becomes larger ≥11 RS. (4) The azimuthal ring current intensity develops a maximum between approximately 8 and 12 RS, reaching values of 100–150 pA/m2. Outside this region, it drops with radial distance faster than the 1/r rate assumed by typical disk current models even though the total current is not much different to the model results.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Saturn, ring current
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 11 Dec 2014 17:30
    Last Modified: 27 Oct 2015 16:13
    URI: http://eprints.bbk.ac.uk/id/eprint/11298

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