Ion Heating in Inhomogeneous Expanding Solar Wind Plasma: The Role of Parallel and Oblique Ion-Cyclotron Waves

摘要: Remote sensing observations of coronal holes show that heavy ions are hotter than protons and their temperature is anisotropic. In-situ fast solar wind streams provide direct evidence for turbulent Alfv\'en wave spectrum, left-hand polarized ion-cyclotron waves, He$^{++}$ -- proton drift in the plasma, which can produce anisotropies by resonant absorption perpendicular heating ions. Furthermore, expected to be inhomogeneous on decreasing scales approaching Sun. We study plasma with a 2.5D hybrid code. include expansion an background, combined effects spectrum Alfv\'enic fluctuations initial ion-proton drifts. influence these ion cooling magnetic background wind. find inhomogeneities lead enhanced compared homogenous wind, generation significant power oblique waves plasma. The effect due not super-Alfv\'enic drifts, diminished further when we inhomogenous density. reproduce anisotropy seen previous models, present regardless expansion. conclude small scale inner heliosphere significantly affect heating.