Nano-shaped hot-wire for ultra-high resolution anemometry in cryogenic helium

We present the principle, modeling, and the first implementation of a new type of high resolution hot-wire anemometer designed to operate at cryogenic temperatures and very high Reynolds numbers. Its spatial resolution of a few micrometers is comparable to the most spatially resolved hot-wires reported in the literature. Compared to existing designs, its fabrication involves a limited number of steps, essentially the shaping at nanoscales of a superconducting NbTi wire of submicron diameter. The velocity spectra in the far wake of a centimeter-sized grid are measured as a proof of concept in stringent flow conditions.