Cantilever anemometer in the bulk of a liquid helium flow.
Main dimensions of the probe and niobium pattern of the micro-resonator circuit. The three grayscale images are SEM pictures.
Schematic description of the deep-etching steps. (a) Bulk silicon wafer with aluminum masks on both sides. (b) 1μm-deep RIE etching of top side. (c) Deep-etching of bottom side until a leak is detected. (d) Final structure after cleaning the aluminum layers.
Transmission coefficient S 21 through the superconducting feedline (see text) measured with a Vector Network Analyser at T = 1.67 K. The input power on the feedline is −20 dBm. The resonance frequency of this LC-resonator is 952 MHz. The quality factor is Q ≈ 103. The fluid mean velocity is either zero (black dashed line) or ≈ 1m/s (red line). The “working range” corresponds to the frequency range in which the carrier frequency is chosen when the resonator is probed by frequency modulation (see Figure 5).
Electronic diagram used to perform the fluctuations measurements of the cantilever elongation by frequency modulation.
Calibration of the probe in He II. Open green triangles: T = 2.07 K (ρ = 145.8 kg/m3). Red squares: T = 1.82 K (ρ = 145.4 kg/m3). Open blue circles: T = 1.66 K (ρ = 145.3 kg/m3). Insert: Power spectra of the fluctuating signal. From bottom up: 0 m/s and 1m/s at T = 1.66 K, 1.1 m/s and 1.35 m/s at T = 1.82 K. The green arrow points toward the vortex shedding peak.
Article metrics loading...
Full text loading...