  The fluctuations of the vortex density in a turbulent quantum fluid are
deduced from local second-sound attenuation measurements. These measurements
are performed with a micromachined open-cavity resonator inserted across a flow
of turbulent He-II near 1.6 K. The power spectrum of the measured vortex line
density is compatible with a (-5/3) power law. The physical interpretation,
still open, is discussed.
