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This paper addresses the first direct investigation of the energy budget in the solar corona. Exploiting joint observations of the same coronal plasma by Parker Solar Probe and the Metis coronagraph aboard Solar Orbiter and the conserved equations for mass, magnetic flux, and wave action, we estimate the values of all terms comprising the total energy flux of the proton component of the slow solar wind from 6.3 to 13.3 R ⊙. For distances from the Sun to less than 7 R ⊙, we find that the primary source of solar wind energy is magnetic fluctuations including Alfvén waves. As the plasma flows away from the low corona, magnetic energy is gradually converted into kinetic energy, which dominates the total energy flux at heights above 7 R ⊙. It is found too that the electric potential energy flux plays an important role in accelerating the solar wind only at altitudes below 6 R ⊙, while enthalpy and heat fluxes only become important at even lower heights. The results finally show that energy equipartition does not exist in the solar corona. [ABSTRACT FROM AUTHOR]

We present the results of a time-dependent 2.5-dimensional three-fluid magnetohydrodynamic model of the coronal streamer belt, which is compared with the slow solar wind plasma parameters obtained in the extended corona by the UV spectroscopic data from the Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO during the past minimum of solar activity (Carrington Rotation 1913). Our previous three-fluid streamer model has been improved by considering the solar magnetic field configuration relevant for solar minimum conditions, and preferential heating for O5+ ions. The model was run until a fully self-consistent streamer solution was obtained in the quasi-steady state. The plasma parameters from the multi-fluid model were used to compute the expected UV observables from H I Lyα 1216 Å and O VI 1032 Å spectral lines, and the results were compared in detail with the UVCS measurements. A good agreement between the model and the data was found. The results of the study provide insight into the acceleration and heating of the multi-ion slow solar wind. [ABSTRACT FROM AUTHOR]