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Improved Acoustic Thermometry for Long-Distance Temperature Measurements
Get PDFAccurate measurements of long distances (in the order of tens of meters or more) are necessary in manufacturing processes of large structures, as, for example, in the aerospace industry. In the most demanding applications, the goal is to achieve a relative accuracy of 10(-7) in the measurement of distances (e.g., 1 mu m over 10 m). This goal can be obtained with laser interferometers whose accuracy is based on knowledge of the speed of light, which, in turn, depends on the temperature of air. A thermometer based on the measurement of the speed of sound in air has been realized at INRIM. Its purpose is the measurement of the air temperature along the measurement path of the interferometer with an accuracy of 0.1 degrees C at distances up to 11 m. The paper describes the principle and the experimental setup of the acoustic thermometer and demonstrates its performance by comparison with calibrated reference platinum resistance thermometers. Furthermore, we demonstrate the potentiality of the method to measure the vertical temperature gradient, which is the main error source in triangulation measurements when using laser trackers
Suppression of spin-wave nonreciprocity due to interfacial Dzyaloshinskii-Moriya interaction by lateral confinement in magnetic nanostructures
No full textDespite the huge recent interest towards chiral magnetism related to the interfacial Dzyaloshinskii-Moriya interaction (i-DMI) in layered systems, there is a lack of experimental data on the effect of i-DMI on the spin-wave eigenmodes of laterally confined nanostructures. Here, we exploit Brillouin light scattering (BLS) to analyze the spin-wave eigenmodes of noninteracting circular and elliptical dots, as well as of long stripes, patterned starting from a Pt(3.4-nm)/CoFeB(0.8-nm) bilayer, with lateral dimensions ranging from 100 to 400 nm. Our experimental results, corroborated by micromagnetic simulations based on the graphic processing units-accelerated mumax3 software package, provide evidence for a strong suppression of the frequency asymmetry Δf between counterpropagating spin waves (corresponding to either Stokes or anti-Stokes peaks in BLS spectra), when the lateral confinement is reduced from 400 to 100 nm, i.e., when it becomes lower than the light wavelength. Such an evolution reflects the modification of the spin-wave character from propagating to stationary and indicates that the BLS-based method of quantifying the i-DMI strength from the frequency difference of counterpropagating spin waves is not applicable in the case of magnetic elements with lateral dimension below about 400 nm
Vortex dynamics in NbTi films at high frequency and high DC magnetic fields
No full textWe report on the characterization of NbTi films at ∼ 11 GHz and in DC magnetic fields up to 4 T, performed by means of the coplanar waveguide resonator technique, providing quantitative information about the penetration depth, the complex impedance, and the vortex-motion-induced complex resistivity. This kind of characterization is essential for the development of radiofrequency cavity technology. To access the vortex-pinning parameters, the complex impedance was analyzed within the formalism of the Campbell penetration depth. Measurements in this frequency range allowed us to determine the complete set of vortex-pinning parameters and the flux flow resistivity, both analyzed and discussed in the framework of high-frequency vortex dynamics models. The analysis also benefits from the comparison with results obtained by a dielectric-loaded resonator technique on similar samples and by other ancillary structural and electromagnetic characterization techniques that provide us with a comprehensive picture of the material. It turns out that the normalized flux flow resistivity follows remarkably well the trend predicted by the time dependent Ginzburg-Landau theory, while the pinning constant exhibits a decreasing trend with the field which points to a collective pinning regime
Skin effect and losses in soft magnetic sheets: from low inductions to magnetic saturation
No full textSaturation vapour pressure measurements of refrigerant R1224yd(Z) from 274 K to 338 K
No full textA new generation of refrigerant fluids, such as hydrofluorolefines (HFOs) and hydrochlorofluorolefines (HCFOs), has been recently introduced in order to increase the availability of zero-ODP (Ozone Depletion Potential) and low-GWP (Global Warming Potential) refrigerants. Among the HCFOs, the refrigerant HCFO-1224yd(Z) captured more attention due to its very low GWP (<1), negligible ODP (0.00023), non-flammability, low toxicity, and good chemical and thermal suitability. Due to its novelty, there is still a lack of thermodynamic property data about this refrigerant including, e.g. the saturation vapour pressure measurements that have been performed only in few experimental works, one of them used to develop the first equation of state in 2017. At INRIM, saturation vapour pressure measurements of the HCFO-1224yd(Z) were carried out in the temperature range from 274 K to 338 K, improving the measurement accuracy of previously available works. The experimental approach was based on a static method where the set-up consisted of a sample cell immersed into a temperature -controlled calibration bath with millikelvin stability, connected to a precision capacitance manometer with a measurement full scale of 0.5 MPa operating at a constant temperature of 373 K. The experimental work and the measurement results are reported together with a comprehensive uncertainty budget and a comparison against measurement data available from previous works
Metrological characterization of climate reference station thermometers
Get PDFGround-based stations are an essential part of a complex climate observing systems which purpose is to generate data for evaluating local and global climate trends. Measurement traceability in these types of stations is fundamental for generating a robust climate understanding based on comparable data in space and time, both within networked stations and between networks. This importance was expressed by the Global Climate Observing System (GCOS) of the United Nations Environment Programme and WMO (World Meteorological Organization), in its published report 226 that highlights the need for available reference grade observations for accurately detecting of local and global climate trends [1]. As a following action, the GCOS launched in 2022 the implementation plan of its Surface Reference Network (GSRN) where an essential part of the effort is the understanding of instruments performance in field monitoring of temperature, humidity, and pressure. We focused the work here presented on the characterization of resistance thermometers of various types that are candidates to be installed in future prototype reference station. The selection of sensors using resistance measurement principle was motivated by their overall frequent in field use and general superior performance in comparison to other commonly used temperature sensors. The measurements took place under controlled laboratory conditions simulating as close as possible conditions in the field, leading to recommendations on the requirements of instrumentation for a climate reference station. In order to properly determine sensor performance and the components of the measurement uncertainty budget for climate reference stations the metrological parameters as stability, hysteresis and self-heating were determined. These essential parameters were measured in a temperature range typical for air temperature measurements for climate which is from -40 °C up to +60 °C. The characterization of temperature sensors from multiple manufacturers has shown diverging results in all measured parameters which were measured over the whole temperature range. In general, the measurements indicate that from the point of sensor stability the critical temperatures were 20 °C and -40 °C, with indicated highest temperature instability on the level of 0,02 °C. The highest hysteresis effect has been observed at temperatures of 0 °C and -40 °C with a maximum of 0,05 °C. Sensor self-heating exhibits multiple dependencies of the level of supply current that vary with tested sensor and temperature point. This research was made possible thanks to the project (19SIP03- Climate Reference Station) which has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. This work is part of the opening activities for a future GSRN affiliated research facility
