  At high field levels, field emission losses in superconducting cavities have
an adverse effect in both reducing the otherwise extremely high Q > 10^9, and
the magnetic breakdown field bringing it well below the critical magnetic field
of the superconductor. The two effects may well be related as field enhancing
whiskers responsible for the field emission losses can be driven normal thus
reducing the magnetic breakdown field. Both the beneficial and deleterious
effects of anodizing the inner surface of superconducting cavities are
discussed and analyzed.
