  By means of the linear dynamic conductivity, inductively measured on
epitaxial films between 30mHz and 30 MHz, the transition line $T_g (B)$ to
generic superconductivity is studied in fields between B=0 and 19T. It follows
closely the melting line $T_m (B)$ described recently in terms of a blowout of
thermal vortex loops in clean materials. The critical exponents of the
correlation length and time near $T_g (B)$, however, seem to be dominated by
some intrinsic disorder. Columnar defects produced by heavy-ion irradiation up
to field-equivalent-doses of $B_{\phi} = 10T$ lead to a disappointing reduction
of $T_g (B \to 0)$ while for $B>B_{\phi}$ the generic line of the pristine film
is recovered. These novel results are also discussed in terms of a loop-driven
destruction of generic superconductivity.
