  Two experiments on the OMEGA Laser System used oblique proton radiography to
measure magnetic fields in cylindrical implosions with and without an applied
axial magnetic field. Although the goal of both experiments was to measure the
magnitude of the compressed axial magnetic field in the core of the implosion,
this field was obfuscated by two features in the coronal plasma produced by the
compression beams: an azimuthal self-generated magnetic field and small length
scale, high-amplitude structures attributed to collisionless effects. In order
to understand these features, synthetic radiographs are generated using fields
produced by 3-D HYDRA simulations. These synthetic radiographs reproduce the
features of the experimental radiographs with the exception of the small-scale
structures. A direct inversion algorithm is successfully applied to a synthetic
radiograph, but is only partially able to invert the experimental radiographs
in part because some protons are blocked by the field coils. The origins of the
radiograph features and their dependence on various experimental parameters are
explored. The results of this analysis should inform future measurements of
compressed axial magnetic fields in cylindrical implosions.
