The low energy plasma in the Jovian magnetosphere

• Published in: Geophysical research letters Vol. 7; no. 1; pp. 17 - 20
• Main Authors: Belcher, J. W., Goertz, C. K., Bridge, H. S.
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.01.1980
• Subjects: Acceleration; Charged particles; Corotation; Geophysics; Low energy; Positive ions; Spacecraft
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/GL007i001p00017

Measurements below 6 keV from the plasma science experiment on the Voyager spacecraft show that positive ions with temperatures as low as 30 eV to several keV are observed to distances at least as great as 40 RJ in the dayside Jovian magnetosphere. When velocity determinations are possible between ∼ 10 RJ and ∼40 RJ, the plasma velocity component along the rigid corotation direction is found to be consistently less than the full corotation speed. Positive ion measurements above ∼28 keV from the low energy charged particle experiment on Voyager demonstrate the existence of positive ions with temperatures of 20‐30 keV at all distances greater than 30 RJ. Taken together, these observations suggest that the low energy plasma population from ∼30 RJ to at least 40 RJ frequently contains both a cold and a hot component. A two‐component plasma of this nature may indicate different sources, acceleration mechanisms, or time histories for the disparate components. It may also be indicative of a single acceleration mechanism which is highly energy dependent.