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Galileo energetic particles detector measurements of hot ions in the neutral sheet region of Jupiter's magnetodisk
Author(s) -
Kane M.,
Williams D. J.,
Mauk B. H.,
McEntire R. W.,
Roelof E. C.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900267
Subject(s) - jupiter (rocket family) , jovian , physics , ion , atmosphere of jupiter , magnetosphere , atomic physics , computational physics , astrophysics , saturn , spacecraft , astronomy , planet , plasma , nuclear physics , quantum mechanics
Hot ions discriminated by mass, look direction, and energy have been detected by the Energetic Particles Detector (EPD) on the Galileo spacecraft in the Jovian magnetosphere. Using techniques adapted from analysis of Voyager ion measurements, EPD data have been fitted to a three‐species convected κ distribution function using a nonlinear least squares technique. The ion species were assumed to be sulfur, oxygen, and protons of arbitrary charge. The bulk flow speed of ions in the neutral sheet region of Jupiter's magnetodisk deduced from the model was found to increase slightly with increasing radial distance from Jupiter within a 20–60 R J region near local midnight. The resulting flow speed of ∼0.5 times the rigid corotation speed beyond 30 R J is similar to that found from analysis of Voyager measurements. The behavior of protons, sulfur, and oxygen is consistent with adiabatic cooling ( T/B = constant) with increasing radial distance in the region analyzed. The distribution functions are similar to those derived from Voyager measurements, with sulfur contributing the largest component of the total hot ion pressure.