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Paper: Turbulent Heating of the Core Solar Wind Protons in the Outer Heliosphere
Volume: 484, Outstanding Problems in Heliophysics: From Coronal Heating to the Edge of the Heliosphere
Page: 49
Authors: Gamayunov, K.; Zhang, M.; Pogorelov, N.; Heerikhuisen, J.; Rassoul, H.
Abstract: A model of the interstellar pickup protons, slab component of the Alfvénic turbulence, and core solar wind (SW) protons is presented for r 1 AU along with a comparison with the Voyager 2 (V2) observations of the core SW temperature. The main conclusions of our study are summarized as follows. (1) A combined effect of the Wentzel–Kramers–Brillouin attenuation, large-scale driving, and pickup proton generated waves results in the turbulent energy sink in the region 1 AU < r < 10 AU, while energy is pumped in the turbulence beyond ∼ 10 AU. Without energy pumping the nonlinear energy cascade is suppressed for r < 10 AU. A similar situation takes place for the 2D turbulence. (2) For both the slab and 2D turbulent components at the heliocentric distances r < 10 AU, the energy source for the core SW protons due to the Alfvén wave dissipation is small. As a result, adiabatic cooling mostly controls the model SW temperature in this region, and the model temperature disagrees with the V2 observations in the region r < 20 AU. (3) The model core SW temperature agrees well with the V2 observations for r > 20 AU.
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