  Due to its very low viscosity, cryogenic helium has been used for years to
generate high Reynolds turbulent flows. The measurement of velocity
fluctuations in such high Reynolds flows is however a challenging issue, as it
is necessary to develop small size (typically micron-length), robust sensors,
to measure the whole spectrum of fluctuations of the velocity, which may extend
to hundreds of kHz and possibly higher. SBT has developed for years different
facilities, in particular taking benefit of the refrigeration capacities
available at CEA Grenoble. In this article we present the current status of
developments of hot wire sensors at CEA. Different characterizations of
Wollaston hot wires are shown, and measurements of velocity fluctuations in
different conditions, in normal helium as well as in superfluid helium are
shown.
