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Ionospheric outflow of plasma and compression relationship in the plasma sheet
Author(s) -
Liu W. W.,
Rostoker G.
Publication year - 1990
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/gl017i011p01849
Subject(s) - polytropic process , plasma , outflow , ionosphere , physics , adiabatic process , plasma sheet , solar wind , flux tube , atomic physics , astrophysics , computational physics , atmospheric sciences , geophysics , meteorology , thermodynamics , magnetosphere , nuclear physics , magnetic flux , magnetic field , quantum mechanics
We are concerned in this article with the curious finding of Huang et al. [1989] which suggests a polytropic index of plasma compression of about 0.7 in the quiet time central plasma sheet. We show that the reduction of this index from its adiabatic value (=5/3) can be achieved through an ionospheric outflow of plasma which lowers the plasma temperature by virtue of energy partition. The observed correlation between the plasma temperature and density is best reproduced by an ionospheric source of ∼5×10 25 ions/s, consistent with independent experinental estimates and smaller than the average solar wind source by a factor of two or more. Despite the change in the polytropic relationship, we find that the global energy equation PV 5/3 =constant (V=volume of a unit flux tube) still holds approximately (in the absence of other energy‐loss mechanisms).