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Paper: Temperature Anisotropy Upper Bounds and Low-Frequency Electromagnetic Fluctuations in the Solar Wind
Volume: 484, Outstanding Problems in Heliophysics: From Coronal Heating to the Edge of the Heliosphere
Page: 248
Authors: Yoon, P. H.; Seough, J.; Gaelzer, R.
Abstract: As the solar wind expands, the density and magnetic field decrease, thus leading to the parallel temperature anisotropy. Perpendicular anisotropy is generated when the solar wind is compressed against the Earth's magnetosphere. Threshold conditions for the temperature anisotropy can be constructed on the basis of marginal kinetic instability theory. However, the actual solar wind is found in the linearly stable regime for these instabilities. Consequently, the source of electromagnetic fluctuations in such a regime is an outstanding problem. The present paper first reviews the theory of temperature anisotropy upper bounds. Then the theory of spontaneous thermal emission of electromagnetic fluctuation in the linearly stable regime is discussed. Theories such as presently discussed may be important to account for the observation made in the solar wind.
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