  We report proton temperature anisotropy variations in the inner heliosphere
with Parker Solar Probe (PSP) observations. Using a linear fitting method, we
derive proton temperature anisotropy with temperatures measured by the Solar
Probe Cup (SPC) from the SWEAP instrument suite and magnetic field observations
from the FIELDS instrument suite. The observed radial dependence of temperature
variations in the fast solar wind implies stronger perpendicular heating and
parallel cooling than previous results from Helios measurements made at larger
radial distances. The anti-correlation between proton temperature anisotropy
and parallel plasma beta is retained in fast solar wind. However, the
temperature anisotropies of the slow solar wind seem to be well constrained by
the mirror and parallel firehose instabilities. The perpendicular heating of
the slow solar wind inside 0.24 AU may contribute to its same trend up against
mirror instability thresholds as fast solar wind. These results suggest that we
may see stronger anisotropy heating than expected in inner heliosphere.
