Heating of the Low-Latitude Solar Wind by Dissipation of Turbulent Magnetic Fluctuations

We test a theory presented previously to account for the turbulent transport of magnetic uctuation energy in the solar wind and the related dissipation and heating of the ambient ion population. This theory accounts for the injection of magnetic energy through the damping of large-scale ow gradients such as wind shear and compression, and incorporates the injection of magnetic energy due to wave excitation by interstellar pickup ions. The theory assumes quasi-2D spectral transport of the uctuation energy and subsequent dissipation that heats the thermal protons. We compare the predictions of this theory with Voyager 2 and Pioneer 11 observations of magnetic uctuation energy, magnetic correlation lengths, and ambient proton temperatures. Near-Earth Omnitape observations are used to adjust for solar variability and the possibility that high-latitude e ects could mask possible radial dependences is considered. We nd abundant evidence for in situ heating of the protons, which we quantify, and show that the observed magnetic energy is consistent with the ion temperatures.