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Kinetic temperature ratios of O 6+ and He 2+ : Observations from Wind/MASS and Ulysses/SWICS
Author(s) -
Cohen C. M. S.,
Collier M. R.,
Hamilton D. C.,
Gloeckler G.,
Sheldon R. B.,
von Steiger R.,
Wilken B.
Publication year - 1996
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 - 10.1029/96gl00587
Subject(s) - physics , kinetic energy , solar wind , wind speed , mass ratio , mean kinetic temperature , thermal , astrophysics , computational physics , atmospheric sciences , thermodynamics , meteorology , plasma , nuclear physics , classical mechanics
We present results from a two spacecraft study of the ratio of O 6+ and He 2+ kinetic temperatures as a function of solar wind speed. Data from the Wind/MASS and Ulysses/SWICS instruments both indicate the O 6+ /He 2+ kinetic temperature ratio increases with increasing solar wind speed, peaking near 500 km/s. Above 500 km/s, the ratio appears to decrease slightly. Values near unity were obtained for slow solar wind while fast wind yielded ratios substantially higher than what is expected from the general rule Although averaging over all data would result in the nominal ratio of 4, deviations from equation (1) appear to be common and the assumption of equal thermal velocities should not be made a priori.