  The properties of magnetic fields forming an extended plage region in AR
10953 were investigated. Stokes spectra of the Fe I line pair at 6302 \AA
recorded by the spectropolarimeter aboard the Hinode satellite were inverted
using the SPINOR code. The code performed a 2D spatially coupled inversion on
the Stokes spectra, allowing the retrieval of gradients in optical depth within
the atmosphere of each pixel, whilst accounting for the effects of the
instrument's PSF. Consequently, no magnetic filling factor was needed. The
inversion results reveal that plage is composed of magnetic flux concentrations
(MFCs) with typical field strengths of 1520 G at log(\tau)=-0.9 and
inclinations of 10-15 degrees. The MFCs expand by forming magnetic canopies
composed of weaker and more inclined magnetic fields. The expansion and average
temperature stratification of isolated MFCs can be approximated well with an
empirical plage thin flux-tube model. The highest temperatures of MFCs are
located at their edges in all log(\tau) layers. Whilst the plasma inside MFCs
is nearly at rest, each is surrounded by a ring of downflows of on average 2.4
km/s at log(\tau)=0 and peak velocities of up to 10 km/s, which are supersonic.
The downflow ring of an MFC weakens and shifts outwards with height, tracing
the MFC's expansion. Such downflow rings often harbour magnetic patches of
opposite polarity to that of the main MFC with typical field strengths below
300 G at log(\tau)=0. These opposite polarity patches are situated beneath the
canopy of their main MFC. We found evidence of a strong broadening of the
Stokes profiles in MFCs and particularly in the downflow rings surrounding MFCs
(expressed by a microturbulence in the inversion). This indicates the presence
of strong unresolved velocities. Larger magnetic structures such as sunspots
cause the field of nearby MFCs to be more inclined.
