Cryogenic Temperature Measurement Research Articles

Polymer‐coated fiber Bragg Grating Sensor for cryogenic temperature measurements

AbstractCryogenic temperature sensing has been demonstrated using Polymer coated Fiber Bragg Grating Sensor, and the experimental results are presented in this article. Teflon coating thicknesses of 20 and 40 μ applied on Fiber Bragg Gratings, inscribed in silica fiber (TFBG) are used for these studies. It was observed that the sensitivity of Teflon‐coated FBG has been enhanced three times compared to uncoated regular FBGs. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1154–1157, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25914

Cryogenic temperature measurement of THz meta-resonance in symmetric metamaterial superlattice

A symmetric metamaterial superlattice is introduced accommodating a high Q-factor trapped mode. THz time-domain spectroscopy is employed to measure the transmission spectra, identifying the excitation of trapped and open-modes in the meta-resonances. A finite-difference-time- domain calculation showed that the trapped mode excitation is from the cancelation of current densities among the nearest-neighboring meta-particles. A cryogenic temperature THz measurement is carried out to examine the temperature dependence of resonance characteristics of meta-resonances. At low temperatures, the temperature-independent radiative damping is dominant for the open-mode, while the Q-factor of the trapped mode is determined by the temperature-dependent phonon scattering and temperature-independent defect scattering with the radiative damping significantly suppressed. When compared with the room temperature measurement, a 16% increase in Q-factor is observed for the trapped mode, while a 7% increase for the open-mode at the cryogenic temperature.

An optical system for cryogenic temperature measurements

Fiber optics with a photo-imprinted Bragg grating have been studied for potentialuse as temperature sensors in cryogenic applications. Sensors were coupled withdifferent metallic materials to improve the measurement sensitivity in the very lowtemperature region, i.e. 4.2–30 K. Various coatings were deposited on the externalfiber surface, and full characterization of the tested sensors is given in the paper.

Raman and excitonic photoluminescence characterizations of ZnO star-shaped nanocrystals

Optical properties of ZnO star-shaped nanostructures grown by wet chemical solution method were investigated by using Raman scattering and temperature-dependent photoluminescence. High intensity of Raman mode E 2 high with narrow FWHM of 9 cm −1 appearing at 436 cm −1 indicates the good quality of ZnO wurtzitic structure. Temperature-dependent ultraviolet photoluminescence was studied over the temperature range from 78 to 293 K. At low-temperatures and low-excitation intensities, the dominant spontaneous emissions are due to radiative recombination of excitons bound to donors and one longitudinal optical phonon assistant free exciton A. Finally, only the first-order longitudinal–optical phonon replica of the A free exciton recombination was observed at room temperature. The exciton emission behaviour, including excitonic energy, intensity and line width dependents on the temperature and excitation intensities are discussed. The deep-level emission band is barely observable both at room temperature and at cryogenic temperature measurements.

Erbium-doped intrinsic fiber sensor for cryogenic temperature measurement

A fluorescence-based temperature sensor based on Er-doped fiber for use in the cryogenic temperature ( T) region (77 ≤ T ≤ 273 K) as well as having been demonstrated for the high temperature region (273 ≤ T ≤ 1200 K) is discussed and its performance reported. Good stability and sensitivity is seen, with a range of such fibers, showing a precision in the measurement of ± 5 K. The configuration is simple, employing commercial doped fiber and readily available laser diode sources and photodiode detectors, and the results obtained are compared with those using alternative approaches.

97/00684 Cryogenic temperature measurement for large applications

97/00684 Cryogenic temperature measurement for large applications

Cryogenic temperature measurement for large applications

We have developed a resistance thermometry system for the acquisition, control and monitoring of temperature in large-scale cryogenic applications. The resistance of the sensor is converted to a voltage using a self-balancing AC bridge circuit featuring square-wave excitation currents down to 1 nA. The system is easily scalable and includes intelligent features to treat special situations such as magnet quenches different from normal operation.

Optical fibre temperature sensor in the cryogenic range

The realization of an optical fibre sensor applied to cryogenic temperature measurement in harsh environments is presented. The measurement principle is based on the analysis of the decay-time of the fluorescence emitted by special doped crystals, the excited state lifetimes of which are greatly dependent on temperature. The sensor is intended to work in the presence of strong perturbations encountered on the testing benches of the liquid hydrogen and liquid oxygen turbo-pumps of the Ariane 5 Vulcan engine developed by ‘la Societé Européenne de Propulsion (SEP)’.

Cryogenic temperature measurement

Cryogenic thermometry is almost always carried out by contact techniques. The use of thermal radiation has certainly some application in the mid-infrared but the available radiant energy rapidly decreases as the temperature falls below 0°C.

Cryogenic thermoelectric thermometer using a heat tube

An original application of heat tubes is proposed for increasing the accuracy of cryogenic temperature measurement. This is achieved by supplementary action on the working end of the thermocouple, based on the tube's heat energy transmission, controlled by a magnetic field.

Serrodyne fibre-optic gyroscope with high-scale factor performance

The realization of an optical fibre sensor applied to cryogenic temperature measurement in harsh environments is presented. The measurement principle is based on the analysis of the decay-time of the fluorescence emitted by special doped crystals, the excited state lifetimes of which are greatly dependent on temperature. The sensor is intended to work in the presence of strong perturbations encountered on the testing benches of the liquid hydrogen and liquid oxygen turbo-pumps of the Ariane 5 Vulcan engine developed by ‘la Societé Européenne de Propulsion (SEP)’.

カーボン抵抗温度計の極低温における特性の評価

Resistance vs. temperature relations of 200 carbon resistors (Allen Bradley 100Ω, 1/8W), widely used for cryogenic temperature measurements, were investigated in the range between liquid helium temperature and 20K. Obtained data are statistically evaluated, and it is apparently shown that the difference of the carbon resistor's lot affects the resistance value at the cryogenic temperatures. Four empirical formulas for the resistance vs. temperature relation proposed by other researchers are evaluated. According to this result, the equation, logR+K/logR=A+B/T, proposed by Clement et al. has most precise fitting below 10K. The authors propose a new empirical equation by applying Clement's equation. It is found that the three undecided coefficients, A, B and K of the equation can be calculated from the resistance at 4.2K alone, thus enabling one-point calibration at liquid helium temperature. Resistance changes caused by ten times temperature cyclings from room temperature to liquid helium temperature are also measured. These are within -0.05-+0.02K, though measurments are slightly diverged by temperature cyclings.

Measurement of Carbon Concentration in Polycrystalline Silicon Using FTIR

The carbon concentration in polycrystalline silicon produced via the Siemens process, the hydrogen reduction of trichlorosilane, was evaluated using FTIR. Samples measured included: as grown polycrystalline silicon, high‐temperature annealed polycrystalline silicon, and float zone refined single‐crystalline silicon. It was found that infrared measurements made on high‐temperature annealed polycrystalline silicon samples display similar carbon concentrations as those obtained on float zone refined single‐crystalline silicon samples. Little, if any, evidence exists for the occurrence of significant amounts of interstitial carbon in low carbon concentration polycrystalline silicon material. High‐temperature annealing of polycrystalline silicon results in improved spectrum quality, and therefore, reduces the detection limit and improves the accuracy of the carbon measurement in polycrystalline silicon. A liquid helium sample Dewar was successfully used for cryogenic temperature measurement resulting in further improvement in sensitivity.

Pt-SiO2 Granular Metals for Cryogenic Thermometry in High Magnetic Fields

ABSTRACTPt-SiO2 granular metal films were produced by RF diode sputtering and characterized as thermistors for cryogenic temperature measurements at high magnetic fields. The devices were found to have high sensitivity and small magnetoresistance. This, together with ease of fabrication and stability, makes such thermistor useful candidates for cryogenic thermometry.

112. A Mueller bridge set for cryogenic temperature measurements: J M Diamond,J Sci Instrum, 43,1966, 576–580

112. A Mueller bridge set for cryogenic temperature measurements: J M Diamond,J Sci Instrum, 43,1966, 576–580

Carbon resistors for cryogenic temperature measurement

Carbon resistors for cryogenic temperature measurement

A Mueller bridge set for cryogenic temperature measurements

An a.c. Mueller bridge set for resistance thermometry at cryogenic temperature is described. A commercial tuned null detector is used at an operating frequency of 1025 c/s. The set includes a high stability oscillator, line reject filter, phase shifter, Q multiplier and selector box. The latter permits the dissipation in the thermometers not being measured to be maintained at the operating level with direct current. A temperature change of the order of 10 μdegK can be detected with 10-8 W applied to the thermometer.