  The Quasi-thermal noise (QTN) technique is a reliable tool to yield accurate
measurements of the electron parameters in the solar wind. We apply this method
on Parker Solar Probe (PSP) observations to derive the total electron
temperature ($T_e$) from the linear fit of the high-frequency part of the QTN
spectra acquired by the RFS/FIELDS instrument, and present a combination of
12-day period of observations around each perihelion from Encounter One (E01)
to Ten (E10) (with E08 not included) with the heliocentric distance varying
from about 13 to 60 solar radii ($R_\odot{}$). We find that the total electron
temperature decreases with the distance as $\sim$$R^{-0.66}$, which is much
slower than adiabatic. The extrapolated $T_e$ based on PSP observations is
consistent with the exospheric solar wind model prediction at $\sim$10
$R_\odot{}$, Helios observations at $\sim$0.3 AU and Wind observations at 1 AU.
Also, $T_e$, extrapolated back to 10 $R_\odot{}$, is almost the same as the
strahl electron temperature $T_s$ (measured by SPAN-E) which is considered to
be closely related to or even almost equal to the coronal electron temperature.
Furthermore, the radial $T_e$ profiles in the slower solar wind (or flux tube
with larger mass flux) are steeper than those in the faster solar wind (or flux
tube with smaller mass flux). More pronounced anticorrelated $V_p$-$T_e$ is
observed when the solar wind is slower and closer to the Sun.
