Parker Solar Probe (PSP), launched on August 12th, 2018, is an ongoing mission to probe the solar corona (perihelion from 35.7 solar radii (Rs) to 9.86 Rs). In particular, this gives us an opportunity to study the solar wind energy flux in the inner heliosphere, which is of great importance to determine the acceleration of the solar wind at the base of the corona. We investigate the solar wind energy flux in the inner heliosphere using 12-day observations around each perihelion of Encounter One

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... (E01), Two (E02), Four (E04), and Five (E05) of PSP, respectively, with a minimum heliocentric distance of 27.8 Rs. Energy flux is calculated based on electron parameters (density ne, core electron temperature Tc, and suprathermal electron temperature Th) obtained by analyzing plasma quasi-thermal noise (QTN) spectrum measured by RFS/FIELDS and the bulk proton parameters (bulk speed Vp, and temperature Tp) measured by SPC/SWEAP. Combining observations from E01, E02, E04, and E05, the averaged energy flux value normalized to 1 Rs plus the energy necessary to overcome the solar gravitation (WR⊙) is about 70 ± 14 W/m2, similar to the average value (79 ± 18 W/m2) derived by Le Chat et al. (2012) from 24-year observations by Helios, Ulysses, and Wind at various distances and heliolatitudes. It is remarkable that the distributions of WR⊙ are nearly symmetrical and well fitted by Gaussians, much more so than at 1 AU, which may imply that the small heliocentric distance limits the interactions with transient plasma structures.