  The density fluctuations of quantum vortex lines are measured in a turbulent
flow of superfluid He, at temperatures corresponding to superfluid fraction of
16%, 47% and 81%. The probe is a micro-fabricated second sound resonator that
allows for local and small-scale measurements in the core of the flow, at a
10-mesh-size behind a grid. Remarkably, all the vortex power spectra collapse
on a single master curve, independently from the superfluid fraction and the
mean velocity. By contrast with previous measurements, we report an peculiar
shape of the power spectra. The vortex density probability distributions are
found to be strongly skewed, similarly to the vorticity distributions observed
in classical turbulence. Implications of those results are discussed.
