  An estimate of the London penetration and coherence lengths in the vacuum of
the SU(3) pure gauge theory is given downstream an analysis of the transverse
profile of the chromoelectric flux tubes. Within ordinary superconductivity, a
simple variational model for the magnitude of the normalized order parameter of
an isolated vortex produces an analytic expression for magnetic field and
supercurrent density. In the picture of SU(3) vacuum as dual superconductor,
this expression provides us with the function that fits the chromoelectric
field data. The smearing procedure is used in order to reduce noise.
