Relative contributions of terrestrial and solar wind ions in the plasma sheet |
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Authors: | W Lennartsson RD Sharp |
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Institution: | Lockheed Palo Alto Research Laboratory, 3251 Hanover Street, Palo Alto, CA 94304, USA |
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Abstract: | A major uncertainty concerning the origins of plasma sheet ions is due to the fact that terrestrial H+ can have similar fluxes and energies as H+ from the solar wind. The situation is especially ambiguous during magnetically quiet conditions (AE < 60γ) when H+ typically contributes more than 90% of the plasma sheet ion population. In this study we examine that problem using a large data set obtained by the ISEE-1 Plasma Composition Experiment. The data suggest that one component of the H+ increases in energy with increasing activity, roughly in proportion to the energy of the He++, whereas the other H+ component has about the same energy at all activity levels, as do the O+ and the He+. If we can assume that the H+ of solar wind origin on the average has about the same energy-per-nucleon as the He++, which is presumably almost entirely from the solar wind, then the data imply that as much as 20–30% of the H+ can be of terrestrial origin even during quiet conditions. |
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