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Abstract

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.