  Observations from Parker Solar Probe's first five orbits are used to
investigate the helioradial evolution of probability density functions (PDFs)
of fluctuations of magnetic field components, between \(\sim 28\) - 200
\(\rs\). Transformation of the magnetic field vector to a local mean-field
coordinate system permits examination of anisotropy relative to the mean
magnetic field direction. Attention is given to effects of averaging-interval
size. It is found that PDFs of the perpendicular fluctuations are well
approximated by a Gaussian function, with the parallel fluctuations less so:
kurtoses of the latter are generally larger than 10, and their PDFs indicate
increasing skewness with decreasing distance \(r\) from the Sun, with the
latter observation possibly explained by the increasing Alfv\'enicity of the
fluctuations. The ratio of perpendicular to parallel variances is greater than
unity; this variance anisotropy becomes stronger with decreasing \(r\). The
ratio of the total rms fluctuation strength to the mean field magnitude
decreases with decreasing \(r\), with a value \(\sim 0.8\) near 1 AU and \(\sim
0.5\) at 0.14 AU; the ratio is well approximated by a \(r^{1/4}\) power law.
These findings improve our understanding of the radial evolution of turbulence
in the solar wind, and have implications for related phenomena such as
energetic-particle transport in the inner heliosphere.
