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Proton temperature change with heliocentric distance from 0.3 to 1 AU according to relative temperatures
Author(s) -
Lamarche Leslie J.,
Vasquez Bernard J.,
Smith Charles W.
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019529
Subject(s) - helicity , physics , anisotropy , power law , energy cascade , plasma , isotropy , adiabatic process , proton , thermodynamics , atomic physics , turbulence , nuclear physics , statistics , optics , mathematics , particle physics
Helios spacecraft data excluding shocks, ejecta, and low‐cadence plasma intervals are averaged into hour‐long intervals and binned by heliocentric distance. In each distance bin, relative classes of fluctuation‐normalized cross helicity and total energy are made with a further refinement of each of these classes according to the relative proton radial component of temperature. The relative classes of temperature itself are also examined. All temperatures in each class are fitted by a power law as a function of heliocentric distance to determine the power law index. The difference between this index and the adiabatic index for isotropic plasma can be the first‐order indicator of heat addition to the plasma. Relative total energy has temperature indices and behaviors that can be consistent with heat addition from a turbulent energy cascade. Relative cross helicity also shows indices that can support heat addition, but the results are inconclusive on heat addition, especially at high cross helicity. A detailed knowledge of the thermal anisotropy, at least, is required in the case of high cross helicity.