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8th
Temperature |
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Temperature Symposium Program Monday, October 21st -- 09:00 - 10:00 Opening Plenary Session, 10:45 - 12:30 Sessions A-1 through A-5, 15:00 - 17:00 Sessions B-1 through B-5 Tuesday, October 22nd -- 08:30 - 10:30 Sessions C-1 through C-5, 10:45 - 12:30 Sessions D-1 through D-5, 15:00 - 17:00 Sessions E-1 through E-5 Wednesday, October 23rd -- 08:30 - 10:30 Sessions F-1 through F-5, 10:45 - 12:30 Sessions G-1 through G-5, 15:00 - 17:00 Sessions H-1 through H-5 Thursday, October 24th -- 08:30 - 10:10 Sessions I-1 through I-4, 10:30 - 11:30 Sessions J-1 through J-4, 11:45 - 12:45 Closing Plenary Session Social Events -- Reception on Sunday, October 20th; Banquet on Wednesday, October 23rd First Author Index -- Last Name, Session Identifier
09:00 - 10:30 -- Opening Plenary Session 9:00 Opening
Remarks, Mr. Larry Rubin, General Chairman 1045 - 1230 -- Session A-1. Thermodynamic Thermometry A-1, 10:45 --
Investigation of the Accuracy of the ITS-90 with Reference to Thermodynamic
Temperature in the Range from 400 °C up to 600 °C For several years Physikalisch-Technische Bundesanstalt (PTB) has performed thermodynamic temperature measurements at a large area blackbody applying filter radiometers based on silicon photodiodes and interference filters with center wavelengths at 676 nm, 800 nm, 900 nm, and 1000 nm. These filter radiometers were used for the determination of possible systematic deviations of temperatures measured according to the International Temperature Scale of 1990 (ITS-90), T90, and the thermodynamic temperatures T. The measurements revealed a difference of 50 mK of T-T90 at temperatures around the freezing point of silver (961.78 °C). The observed difference decreases with decreasing temperatures, indicating that it may be attributed to a systematic deviation in the ITS-90 from T due to the gas thermometric temperature measurement at 457 °C, which has been used as reference temperature for extrapolation of the ITS-90 to higher temperatures. For a further, more detailed investigation it was necessary to measure the difference T-T90 down to temperatures of 420 °C, the temperature of freezing Zinc, which serves as one of the temperature fixed points of the ITS-90. However, the spectral responsivity of silicon photodiodes does not allow their application in filter radiometers with center wavelengths beyond 1000 nm, which are needed for precise thermodynamic temperature measurements below 450 °C. Therefore a filter radiometer with center wavelength around 1600 nm based on an Indium-Gallium-Arsenide photodiode has been developed. The design of this radiometer, the assessment of its spectral responsivity and its temperature dependence will be shown. T-T90 results are presented for the temperature range from 400 °C to 600 °C obtained with filter -radiometers with their center wavelengths at 800 nm, 900 nm, 1000 nm, and 1600 nm. A-1, 11:05 --
Determination of the Thermodynamic Temperature of the Freezing Point
of Copper by Noise Thermometry The thermodynamic
temperature of the freezing point of copper was measured by noise thermometric
methods. A conventional approach was used which combines the noise voltage
of the measuring resistor with that of a reference resistor maintained
at a known temperature. Besides this comparison method the thermometer
is characterized by a two-channel arrangement to eliminate parasitic
noise of electronic components by cross correlation. The thermodynamic
temperature measured at the freezing point of copper amounts to a value
of 1084.54 °C ± 0.12 K (k = 2). This corresponds to the value
of the ITS-90 temperature of this fixed point of 1084.62 °C within
its thermodynamic uncertainty of 0.12 K (k = 2). A-1, 11:25 --
Using Fourier-Transform Blackbody Spectra to Determine Thermodynamic
Temperature in the 600 °C to 1000 °C Range Results of experimental determinations of thermodynamic temperatures using Fourier transform spectroscopy of blackbody radiation sources are presented. These results are augmented by and compared with theoretical simulations of blackbody spectra in order to assess the feasibility and accuracy of the method. Much of the information on thermodynamic temperature contained in such spectral sets is redundant, and we present a method (based on the original suggestion by Gebbie and recent work done at NRC) to exploit this redundancy in a straightforward way to obtain thermodynamic temperatures for each of the spectral sources. Here, we briefly describe the experimental apparatus, the analysis of the most recent experimental results and a comparison with our simulations. A-1, 11:45 --
Techniques for Primary Acoustic Thermometry to 800 K The NIST Primary Acoustic Thermometer will measure the difference between the International Temperature Scale of 1990 and the Kelvin Thermodynamic Scale throughout the range 273 K to 800 K with uncertainties of only a few millikelvins. The acoustic thermometer determines the frequencies of the acoustic resonances of pure argon gas contained within a spherical cavity with uncertainties approaching one part in 106. To achieve this small uncertainty at these elevated temperatures we developed new acoustic transducers and new techniques for the maintenance of gas purity and for temperature control. Lacking a suitable commercial acoustic transducer, we developed novel electro-acoustic transducers based on the capacitance between a flexible, single-crystal, silicon diaphragm and a rigid, stainless-steel, backing plate. These transducers have been used successfully to 575 K. To preserve the purity of the argon, no polymers were used in any components of the acoustic thermometer that contacted the argon. Without the damping usually provided by polymers, mechanical vibrations caused unstable, spurious acoustic signals. We describe the techniques that we developed to suppress vibrations and obtain stable signals. In contrast with constant-volume gas thermometry, acoustic thermometry allows the thermometric gas to be continuously flushed through the resonator, thereby preventing the build up of outgassed impurities. We describe how the argon pressure is stabilized while flushing and measuring resonance frequencies. The argon exiting from the resonator is sampled directly and analyzed with a customized gas chromatograph. The dominant impurity is hydrogen that evolves from the stainless steel resonator. To determine the thermodynamic temperature within a few millikelvins, the temperature of the resonator must be stable and uniform to within 1 mK during the measurement. Because the acoustic resonator was so large-it has an outer diameter of 20 cm-a sophisticated furnace, based on surrounding the resonator with three concentric aluminum shells, was designed to achieve this goal. We describe the design, modeling, and operational characteristics of the furnace. A-1, 12:05 --
Progress in Primary Acoustic Thermometry at NIST: 273 K to 505 K In the limit of
zero pressure, the speed of sound in a monatomic gas is a measure of
the thermodynamic temperature of the gas. The NIST Acoustic Thermometer
determines the speed of sound in argon, and consequently its thermodynamic
temperature, by measuring the frequencies of both the acoustic and the
microwave resonances of an argon-filled, spherical cavity. The microwave
frequencies determine the thermal expansion of the cavity from 273.16
K to the operating temperatures while the acoustic frequencies determine
the changes of speed of sound in the argon with temperature. We report
our progress in redetermining the thermodynamic temperature of three
fixed points on the International Temperature Scale of 1990: the melting
point of gallium (302.9146 K) and the freezing points of indium (429.7485
K) and tin (505.078 K). Preliminary results for the deviation of thermodynamic
temperature from the ITS-90 defined temperature are T-T90 = (4.8 ±
0.8) mK at the gallium melting point, and T-T90 = (11.1 ± 1.6)
mK at the indium freezing point, where uncertainties have a coverage
factor of k=1. The measured thermal expansion of the resonator between
the triple point of water and the melting point of gallium, and the
measured deviation of ITS-90 from thermodynamic temperature at the gallium
point are both in excellent agreement with the 1992 determination at
NIST. In these preliminary data, the dominant uncertainties come from
frequency-dependent and time-dependent cross-talk between the electroacoustic
transducers. There is hope for reducing these uncertainties. 10:45 - 12:30 -- Session A-2. Industrial PRTs A-2, 10:45 --
Intercomparison of Pt-100 Thermometers of Some Secondary Laboratories
of Germany and México (DKD And SNC) On the basis of Mutual Recognition Agreements signed by different organization not only the calibration certificates of the National Metrology Institutes, but also of the accredited calibration laboratories should be accepted worldwide. Therefore international intercomparisons should include also secondary laboratories. Such an intercomparison was organized between 8 secondary laboratories in Germany and México using platinum resistance thermometers in the temperature range between -20 °C and 250 °C. The results are analyzed using different methods, including Youden diagrams for the evaluation of the capabilities of the laboratories. A-2, 11:05 --
Efficient Calibration Methods For Platinum Resistance Thermometers Calibration methods for platinum resistance thermometers are simplified by reducing the number of calibration points. For applications that do not require the low uncertainties of the ITS-90 definitions, several modifications are available to improve calibration efficiency. The proposed schemes utilize the ITS-90 reference functions, simplified deviation equations, and in some cases correlations between resistance ratio values. Calibration ranges of interest include: 20 K to 273 K, 273 K to 933 K and various subranges spanning the ice-point from 77 K to 505 K. Thermometers are tested using two to three calibration temperatures with media convenient for comparison calibration. The methods apply to a broad class of thermometers constructed with high purity platinum. Several examples of fit error are presented for standard platinum resistance thermometers (SPRT) and more rugged aerospace sensor designs. Recommendations to minimize the influence of thermal hysteresis are also discussed. The approximations introduce errors typically between 10 mK and 100 mK depending on thermometer type and temperature range. For many applications, these calibration methods satisfy the tradeoff between cost and uncertainty. A-2, 11:25 --
Development of Metal Sheathed Secondary Standard and Precision RTD Thermometer
at Temperatures up to 960 °C and 1,100 °C High quality metal sheathed secondary standard and precision RTD thermometers were developed. They were designed for both laboratory and industrial applications. There are two temperature ranges of the RTD: up to 960°C and up to 1,100°C. The PRT with metal sheath can be used at temperature up to 1,100°C without contamination due to special manufacture process to overcome contamination. This article presents test data to show the stability, hysteresis, and thermal cycle at different temperatures up to 1,100°C. Both secondary standard PRTs and precision industrial RTDs were tested. A-2, 11:45 --
Investigation of Functions W(T90) for Low-a PRTs in the Sub-ranges above
0 °C The most practical method of interpolation for industrial platinum thermometers is the use of the Callendar-Van Dusen second-order equation. Standard tables R(T) for IPRTs of different purity of the platinum wire were established by number of Standards (IEC, DIN, GOST, JIS). From fitting the coefficients B vs. A of the CVD equations, obtained for 166 thermometers with W(100) ranging from 1.380 to 1.392, the linear function B(A) was generated in this work, which makes it possible to establish the second-order reference function for PRTs of any nominal W(100) value. It is important, that substantial distortion of the interpolating CVD curves was found for the IPRTs with film platinum sensing elements. Although the ITS-90 interpolation method is supposed to be applied only to the PRTs, that have a strain-free sensing element made of platinum wire of a very high purity (W(Ga)> 1.11807), it has become usual practice to use the ITS-90 function for industrial thermometers. As shown in the paper, a systematic difference occurs between temperature values calculated by means of the CVD equation and the ITS-90 interpolation technique, which does not depend on the purity of the platinum wire in a large W(100) range, but highly depends on the temperature sub-range. For individual calibration of an IPRT in the sub-range 0-230 °C, it is possible to use only one calibration point, besides 0 °C. A-2, 12:05 --
Maskless Deposition of Platinum for Contact Thermometry Optomec Inc., Albuquerque,
NM, has developed a direct write process that may be used to deposit
resistive thermometers onto low temperature, planar and non-planar surfaces.
The process, Maskless Mesoscale Materials Deposition (M3D), is an aerosol-based
technology that uses an aerodynamically focused stream of droplets or
particles to deposit films of electronic materials onto a wide range
of substrates, including polyimide, FR4, and alumina. The linewidth
of the deposit may be as small as 25 microns, and various geometries
are produced using computer-driven motion control. The deposits are
processed either thermally, or by using laser sintering and laser chemical
decomposition. Optomec has demonstrated thermal and laser chemical decomposition
of Pt precursor deposits on polyimide and alumina, with resistivities
from 3 -10 times that of bulk Pt. This work investigates the feasibility
of using direct write Pt resistors for contact thermometry. A discussion
of XRD and SEM results detailing surface morphology and densification
of the deposits will be given. Results on Pt adhesion to various substrates,
resistance-temperature characteristics, and environmental studies of
the thermometers will be discussed. 10:45 - 12:30 -- Session A-3. Radiation Thermometry - Pyrometers & Detectors A-3, 10:45 --
Design and Construction of a New Primary Standard Pyrometer at NPL National Physical
Laboratory, Teddington, TW11 0LW, United Kingdom A-3, 11:05 --
Use of an InGaAs Radiation Thermometer to Verify the Accuracy of the
NPL Blackbody Reference Sources from 156 °C to 600 °C A transfer standard radiation thermometer based upon an InGaAs detector was developed at the NPL in 2001. The purpose of this instrument was to provide a compact high-resolution device, which could be used to maintain and disseminate a radiance temperature scale between 156 °C and 962 °C. The thermometer requires calibration at the ITS-90 fixed-points. For this purpose fixed-point blackbody sources have been designed and constructed using high purity metals comprising In, Sn, Zn, Al and Ag. Using the results of the calibration, an interpolating equation based upon the Wien function is calculated which relates the thermometer output to the radiance temperature of the source. This paper describes the development of the InGaAs thermometer with results which illustrate its stability between successive calibrations. The InGaAs thermometer was used to verify the calibration of the NPL variable-temperature water and cesium heat-pipe blackbody sources, whose temperatures are normally derived from ITS-90 calibrated SPRTs inserted into the rear of the sources. This was achieved by comparing the radiance temperature of these sources obtained using the calibrated InGaAs thermometer with the ITS-90 contact thermometry at various test temperatures. Allowing for measurement uncertainties and the emissivity of the reference sources, differences within ±0.1°C have been obtained at a number of test temperatures over the range 156 °C and 600 °C. A-3, 11:25 --
The Development and the Characterization of an Absolute Pyrometer Calibrated
for Spectral Radiance Responsivity National Institute
of Standards and Technology, Gaithersburg, MD 20899-8441 USA A-3, 11:45 --
High Accuracy Radiation Thermometer TSP for Radiometric Scale Realization
in the Temperature Range from 600 to 2500 °C All-Russian Research
Institute for Optical and Physical Measurements (VNIIOFI), 46 Ozernaya
St., Moscow, Russia 119361 A-3, 12:05 --
Calibration and Characterization of the Transfer Standard Radiation
Thermometer for APMP Intercomparison APMP Key comparison
of radiance temperature in 0.65 µm was carried out from 1997 to
2000 among seven institutes NMIJ, KRISS, NIM, CSIRO, NMC, KIM-LIPI and
ITRI. Afterward APMP Supplementary comparison of radiance temperature
in 0.9 µm started. Both of the comparisons employ transfer standard
radiation thermometer as a transfer instrument. This paper describes
the calibration and characterization of the 0.65 µm transfer standard
radiation thermometers. The 0.65 µm thermometer was calibrated
according to ITS-90. The copper-point calibration, spectral responsivity
measurement and nonlinearity measurement were carried out. The measured
spectral responsivity was multiplied by Planck equation and was integrated
over wavelength. The coefficient was determined by the copper-point
calibration. The integral scale of the output V at temperature T was
approximated by an interpolation equation, V(T)=C /[exp{c2/(AT+B)}-1].
Here c2 is the second radiation constant and three parameters A, B and
C were determined from the calibrated outputs of the integral calculation
at the copper- point, 2000 °C and 3000 °C. The difference between
the interpolation and the integral calculation was less than 5 mK from
the copper-point to 3000 °C. The nonlinearity was measured by the
two-aperture method. An integrating sphere, a standard lamp and a halogen
lamp were used so that the radiance sources cover from the copper-point
to high radiance. The nonlinearity of the 0.65 µm thermometer
was better than 0.005% in doubling from 960 °C to 2500 °C. The
characterization included zero offset stability, gain ratio, ambient
temperature dependence, long-term stability, stability in transport,
size of source effect and distance effect. 10:45 - 12:30 -- Session A-4. Surface Temperature Measurement A-4, 10:45 --
Traceability of Surface Temperature Measurements using Contact Thermometers Two methods of transferring traceability from contact thermometers calibrated by immersion to thermocouples measuring surface temperature are compared. The temperature of a reference surface is determined (i) by extrapolation from thermometers inserted at different depths, or (ii) by measurement on the surface using a thermally compensated thermocouple. Components of measurement uncertainty are discussed for each technique, and results are compared from 50 °C to 300 °C. A-4, 11:05
-- Temperature Measurements on Nonmetallics in Gas Turbine Engines The gas turbine engine industry has been developing nonmetallics such as ceramic matrix composites (CMCs) and monolithic silicon nitride for use in hot section hardware. New product development requires characterization of the hardware during component and engine testing. Of primary importance in propulsion engine hot sections such as the combustor and turbines is knowledge of thermal patterns and profiles, identification of hot streaks, and component maximum temperatures. This is especially critical information to estimate hardware life and time-in-service between required maintenance inspections and teardowns. Thin-film thermocouples and flame-sprayed aluminum oxide installation methods have been developed and are being used for temperature measurements on these new materials. A-4, 11:25 --
Analysis of Surface Temperature Measurement Errors in Vertical Natural
Convection Cooled Channels This paper describes iterative methodology for calculation of surface temperature measurement errors applied to symmetrically heated, vertical parallel plate channels. Heat transfer calculations within the channel (marching, control volume based, numerical procedure) are first based on initial raw and uncorrected surface temperature measurements. Those data are then utilized for determination of surface measurement errors modeled with emphasis on thermocouple induced local heat sink and convective stray looses. The new, corrected surface temperatures are then input to heat transfer calculations until satisfactory convergence. The scope of the methodology is investigated by it's application to surface measurement error estimation for several groups of channels, each group having different, but fixed height, and variable aspect ratio. The mutual influences of channel geometry and wall temperatures on surface measurement errors at various measurement locations along the channel height are analyzed with results presented in graphical form. It was found that close to the channel entrance errors tend to be significantly augmented due to thermo-siphon induced convective stray looses. As thermal boundary layers approach and meet, errors monotonically decrease and cease to exist in thermally saturated channel sections. It was also found that, because of the non-linearity, the channels with the same aspect ratio but different height, induce different convective stray looses to the sensors. 10:45 - 12:30 -- Session A-5. Novel Contact Thermometers A-5, 10:45 --
Dynamically Self-Validating Contact Temperature Sensors Thermocouple and RTD technology is the workhorse of the temperature measurement industry. It has been refined and extended to cover a broad range of temperature measurement needs. However, it is well documented that these measurement devices experience "drift" or de-calibration while in service. For various reasons the sensor output can "drift" away from representing the true temperature. The magnitude of the drift depends on sensor type, construction, installation and process conditions, but it is well established, though not widely advertised, that these sensors are subject to drift. The real problem is that there has been no way to tell when drift begins to occur or to determine its magnitude, or even its direction. Now, Dynamically Self-Validating Sensors have been invented that eliminate unreliable readings and warn in advance of the onset of drift. In this paper, the technology of Self-Validating Sensors is explained and data is provided showing the performance of a Self-Validating sensor. A-5, 11:05 --
New Generation of Resistance Thermometers Based on Ge Films on GaAs
Substrates The latest achievements in the development of the resistance thermometers based on germanium films on gallium arsenide are summarized. The preliminary results in the development of a new generation of radiation-resistant thermometers and multifunctional sensors for the range from 0.03 K to 400 K and high magnetic fields, based on thin-film microelectronic and micromachining technologies, which have been produced in an international collaboration recently funded by the EU INTAS are introduced. A-5, 11:25 --
A Primary Self-calibrating Thermometer Using Noise of a Tunnel Junction
The wide range of thermometers used in cryogenic systems today all suffer from some combination of lack of absolute accuracy, complexity, and sensitivity to magnetic fields. We describe a primary thermometer that is fast, compact, insensitive to magnetic fields, and operates over a range from millikelvin temperatures to room temperature. The thermometer consists of a 50 Ohm tunnel junction whose noise power is measured by standard techniques of microwave radiometry. In such a junction, the quantum shot noise is an elementary function of the applied bias voltage, the electron's charge, the Boltzmann constant, and the temperature. In contrast to Johnson noise thermometry, this method is self-calibrating and depends only on applied DC voltage, temperature, and fundamental constants. Hence this system may have metrological applications. If we assume that the density of states and the tunneling matrix element are both independent of energy near the Fermi energy, it can easily be shown that the total current through the junction is a linear function of the voltage applied and that the current spectral density of the noise is given by 2eI Coth (eV/kT). This turns out to be realizable for aluminum-aluminum oxide-aluminum tunnel junctions with area of several microns. Because this functional form is independent of temperature at high bias, it can be used to perform a self-calibrating measurement of the thermal noise of the junction. This eliminates the need for detailed calibration of the amplifier chain that makes Johnson noise thermometry so difficult. Without being concerned with the frequency dependence of the measurement chain, we can use a much higher bandwidth than is possible in Johnson noise thermometry (of order 10^8 Hz compared to 10^5 or less for Johnson noise thermometry), allowing for much shorter integration times. We demonstrate that our tunnel junctions exhibit the stated functional form over more that 4 orders of magnitude in temperature. Furthermore, we demonstrate its use as a fast, primary thermometer, and speculate as to its implications both for a thermometer for general use in cryogenic labs and for metrology. A-5, 11:45 --
Spherical Wireless Temperature Sensor The concept of a wireless temperature sensor using spherical semiconductor technology is proposed. Various applications for this sensor are expected in the field where installation of conventional sensors is difficult or impossible. The authors are now developing its first phase prototype. State of development and technical issues are discussed in this paper. This concept can cause a paradigm shift in conventional control systems by the features of wireless, small size and low cost. A-5, 12:05
-- Comparison between a Second Sound Thermometer and a Melting Curve
Thermometer from 0.8 K down to 20 mK BNM-INM realized
the Provisional Low Temperature Scale of 2000 (PLTS-2000) [1]. Aside,
for several years, the low temperature team of BNM-INM was studying
the possibility to use the properties of dilute mixtures of 3He in 4He
in order to develop a local temperature scale. It made the choice to
develop a new type of thermometer based on the propagation of sound
in diluted solutions of helium-3 in superfluid helium-4, a second sound
thermometer. For low temperatures, the properties of low concentrated
3He in superfluid 4He are those of a nearly ideal Fermi gas. The experiments
of Greywall[1] and Owers-Bradley and al.[2] have shown that the velocity
of second sound in 3He-4He mixtures is very sensitive to temperature
and this, specially below 0,5K. In the second sound thermometer developed
by BNM-INM, the speed of the sound is determined from the resonance
spectra of an acoustic cavity. The temperature is deduced from the measurement
of the resonance frequencies, by using a physical model describing the
relation between the speed of sound, the acoustic length of the cavity
and the temperature. This paper will present the experimental results
obtained for the temperature determinations using the second sound thermometer
and for the comparison between this thermometer and the melting curve
thermometer in the temperature range from 0.8 K down to 20 mK. A detailed
budget of uncertainty on the temperature comparison will be given. This
study corresponds to a contribution of BNM-INM to an European research
project, named Ultra Low Temperature dissemination [4]. 15:00 - 17:00 -- Session B-1. Temperature Scales: SPRT Ranges B-1, 15:00 --
Investigation of Non-Uniqueness of the ITS-90 in the Range 13.8 K to
273.16 K In the frame of the European Project "MULTICELLS", Standard Platinum Resistance Thermometers (SPRTs) of NMi-VSL were used to test different designs of transportable modular cells with multiple sealed cryogenic fixed points (H2, Ne, O2 and Ar). During these tests, between four and five SPRTs were simultaneously mounted in the copper comparator block which held the modular fixed point cells, so that the same SPRTs could be calibrated at the cryogenic fixed points of ITS-90 and the new calibrations could be compared to the original ones. Additionally the thermometers were calibrated in mercury triple points used for long-stem thermometers. These calibration results were compared with the earlier calibrations at fixed points and in the gas thermometer to arrive at a full-range ITS-90 calibration. During the cryogenic fixed-point measurements we used the copper comparator block for isothermal measurements on the SPRTs at intermediate temperatures to assess the non-uniqueness of the thermometers. In parallel to this experimental study and for comparison purposes, we recalculated the extensive experimental non-uniqueness study of Compton and Ward on 37 SPRTs for the IPTS-68 to approximate calibration of these SPRTs in terms of ITS-90. We looked at the non-uniqueness of these thermometers in terms of ITS-90 and its sensitivity to our choice of the additional ITS-90 fixed points. From this experimental and mathematical work we could investigate the non-uniqueness of the ITS-90 arising from the intrinsic differences between the individual SPRTs. We compared the non-uniqueness with the uncertainties of these thermometers as progressed from the fixed-point measurements and the estimates involved in these studies. B-1, 15:20 --
Study on Non-uniqueness of ITS-90 in the Temperature Range from 83.8058K
to 273.16K This paper presents the investigations on the non-uniqueness and inconsistency of ITS-90 in the temperature range from 83.8058K to 273.16K with several selected capsule type platinum resistance thermometers, whereas the measurements were carried out in the high precise low temperature cryostat. In the measurements, one thermometer was used as reference with the others calibrated. In order to achieve the high measurement accuracy, two current comparator resistance bridges (model 9975) recorded the readings simultaneously. The measurements on the non-uniqueness were made at the steps of 15K between the fixed points. In addition, the inconsistency of two thermometers was also investigated over the temperature ranging from 13.8K to 273.16K.
Estimates of the non-uniqueness of the ITS-90 are reported based on comparisons of capsule-style standard platinum resistance thermometers at more than eighty temperatures between 13.8033 K and 273.16 K. Using the measurements reported here, as well as those of Ward and Compton and Head, we conclude that the non-uniqueness takes on its largest value (± 0.4 mK) in the range from 83.8058 K to 234.3156 K. This result may have been anticipated due to the fact that the argon and mercury fixed points are separated in temperature by more than 150 K, with no intermediate calibration points. Discussions concerning the details of the temperature scale that will eventually replace the ITS-90 must consider this fact if the non-uniqueness is to be minimized. At the present time, however, there are no candidate fixed points within this temperature range that are realizable to the required level of accuracy for inclusion into a revised International Temperature Scale. B-1, 16:00 --
Realization of the ITS-90 over the Temperature Range 83K to 693 K at
the National Institute for Standards NIS-Egypt Thermometry group of the National Institute for Standards (NIS) has realized the International Temperature Scale 19990 (ITS-90), as defined over the temperature range from 83 K to 2200 °C. This work concerning the temperature range from 83 up to 693 K only. A brief review is given of techniques and apparatuses used, source and purity of the fixed points in this range, cell designs and uncertainties of our realization. B-1, 16:20 --
Realization of the ITS-90 Fixed Points from the Argon Triple Point Upwards:
New Developments at IMGC The actual status of IMGC facilities for the realization of the ITS-90 fixed points is illustrated, including new apparatus for the realization of the triple point of argon and of the freezing points of gold and copper. For each fixed point very long phase transitions are obtained, and several thermometers can be calibrated on each plateau. The present apparatus is described, with the techniques developed at IMGC to obtain well-constant plateaus. Each fixed point is examined, and information on their realization is presented. B-1, 16:40 --
A Quadratic Interpolation Equation for SPRT for Secondary Measurements
in the Range 0 °C to 660.323 °C In the sub-range
from 0 °C to 660.323 °C ,the ITS-90 interpolation equation for
SPIT is a three degree polynomial with respect to the resistance ratio
W(t), determined by the calibration values at the triple point of water
and the fixed points of tin, zinc and aluminum. A quadratic polynomial,
determined by the calibration values at the triple point of water and
the fixed points of tin and aluminum, or at the triple point of water
and the fixed points of zinc and aluminum, is a good approximation to
the ITS-90 interpolation equation in the range from 0 °C to 660.323
°C. This paper proves that the error of the quadratic equation is
about 5 mk., and the accuracy is sufficient for the second measurement. 15:00 - 17:00 -- Session B-2. Base Metal Thermocouples B-2, 15:00 --
Improved Operating Efficiency Through the Use of Stabilized Thermocouples The development of a "stabilized" temperature sensor has led to significant increases in turbine operating efficiency by maximizing output when compared with present sensor technology. These stabilized type K and E thermocouples are superior to existing standard non-stabilized thermocouples because they are not prone to the typical aging effects in the 400 to 600°C (752 to 1112°F) temperature range that can result in measurement errors. A complete set of 18 stabilized type K thermocouples were installed on the exhaust of several gas turbines used for power generation. These thermocouples were subjected to normal operating conditions for a period of one year. During that year, the increase in turbine output has ranged from 0.5% to almost 2.0%. This increase in output also translates into significant cost savings. In addition, the stabilized thermocouples have given the turbine maintenance technicians more confidence in the accuracy of their temperature measurements and resulted in improved troubleshooting and decision making. B-2, 15:20 --
Stability Of A Cable Nicrosil-Nisil Thermocouple Under Thermal Cycling The experimental data on stability of cable Nicrosil-Nisil thermocouples (type N) under stepped thermal cycling in the range of temperatures 20…1100°C and also under continuous heating on air at the temperature 1085±10°? are presented. The analysis of thermal cycling influence on thermal EMF drift is carried out. The conclusion that N type thermocouple can be used as the reference thermocouple while graduation of industrial base-metal thermocouples has been made. B-2, 15:40 --
Development of new Type N Thermocouple for Harsh Environments Temperature measurement can represent a significant burden of cost, through replacement parts, installation time and lost production when applied in difficult environments. The Excalibur was developed by combining a number of existing technologies to address the problems of short life in high temperature, and aggressive or abrasive environments. B-2, 16:00 --
High Resolution Differential Thermocouple Measurements Using an Improved
Noise Cancellation and Magnetic Amplification Technique Electronic Development
Laboratories Incorporated, Danville, Virginia, USA B-2, 16:20 --
High Stability Type K & Type N Thermocouples for Operation up to
1200°C In laboratory experiments,
with microgravity furnaces for example, temperature sensors need to
be small, flexible and very reliable. Thermocoax manufacture high integrity
mineral insulated cables and thermocouples. We have studied the behavior
of type K and type N small diameter thermocouples, in air and under
vacuum, at 1100°C and 1200°C for up to 4,000 hours. Thermocouple
samples were produced from small diameter MI cables (1 to 2 mm, .040"
to .080") and different sheath alloys. The thermoelectric conductors
are extremely small for use at these high temperatures (0.18 to 0.36
mm, .007" to .014"). We selected four different sheath alloys
: two conventional Ni-Cr-Fe alloys and two specific (but commercially
available) alloys one with a high Co content and another one with a
high Al-Y content. Our study has shown that this last special refractory
alloy can very effectively protect the thermoelectric conductors and
lead to very small, and predictable, e.m.f. drifts. This study has shown
interesting results in terms of sheath and conductor corrosion resistance,
grain growth, conductor alloys chemical composition changes with time,
but mainly led to the development of very stable type N and type K thermocouples.
We have shown that type N thermocouples as small as 2 mm in diameter
can drift by less than 10°C after 4000 Hours at 1200°C in air
or under vacuum. A very simple relation was established to estimate
the drift of such a thermocouple versus its outside diameter. B-2, 16:40 --
High Temperature Characteristics of the Ultra Fine Mineral Insulated
Type K Thermocouples Trial manufacture
of the ultra fine diameter and long length type K Mineral insulated
thermocouples (outer diameter 0.25mm and 0.3mm, Length 2000mm and 3000mm
) is made of laser welding method, And it Evaluated of the high temperature
characteristics. The high temperature characteristics is the continuation
heating of 2000 hours at the 600 °C, and the stability test which
implemented 10 hours heating and repeated 10 times at the 600 °C
and shunt error test. The drift of thermal electromotive force in all
test was the within permitted limit. 15:00 - 17:00 -- Session B-3. Radiation Thermometry - Measurement Techniques B-3, 15:00 --
The European Project TRIRAT: Part 1. Experimental Arrangements and Procedures
for the Comparison of Local Temperature Scales with Transfer Infrared
Thermometers between 150 °C And 962 °C In the course of the EC-funded project TRIRAT ("TRaceability in Infrared Radiation Thermometry") an international comparison of local radiation temperature scales took place among fourteen laboratories in the temperature range from 150 °C to 962 °C. This paper describes the equipment and the transfer standards used for the comparison. The results and the procedures adopted for deriving a "comparison reference value" (CRV) and the degree of equivalence of each laboratory with respect to the CRV are then discussed. The different arrangements adopted for the calibration of the thermometers and additional experimental investigations allowed an analysis on the effect of some influencing parameters, e.g., the SSE, to be performed and indications on the most convenient experimental arrangements to be derived. B-3, 15:20 --
A Simple Experimental Technique for Estimation of the Band-pass of Infrared
Radiation Thermometers The infrared radiation thermometer is now becoming a very widely used instrument for industrial temperature measurement and hazardous temperature assessment. Its simple design allows a very low manufacturing cost, and hence its widespread adoption as a convenient non-contact thermometer. The spectral sensitivity of these instruments is usually set by the transmission properties of the windows on the pyrometer, and, although the manufacturer usually makes some statement as to the operating wavelength region, it is difficult to know exactly what is being reported. Calibration laboratories often require knowledge of the band-pass for appropriate calculations of uncertainty, corrections for blackbody emissivity, or, as is commonly becoming required, correction of blackbody radiance temperatures for the calibration of cheaper 'fixed emissivity (eg. 95%)' pyrometers. An explicit measurement of the spectral response of the pyrometer would require a tunable IR source, and special attention to the effects of ambient radiation. This paper presents a very simple experimental technique for the estimation of effective pass-band of an IR radiation thermometer using only a mesh and a blackbody radiator at several temperatures. An analysis of the uncertainty in this determination of the band-pass is also presented. B-3, 15:40 --
A Comparison of Two Methods for Measuring the Nonlinearity of Infrared
Radiation Thermometers The superposition and the dual-aperture methods for measuring the nonlinearity of photodetectors have been compared using three ad hoc devices and testing three radiation thermometers using different detectors. The results of this study have shown that interreflections and interference with the optical beam originating from the nonlinearity device should be considered carefully to avoid large measurement errors particularly with the dual-aperture method. It has also been shown that with some detectors the nonlinearity is mostly generated at the edge of their sensing area. B-3, 16:00 --
The Method of Two-Color Pyrometry of True Temperature with Unknown Emissivity A new pyrometric method (and an experimental two-color pyrometer to realize this method) is suggested for measuring the spectral emissivity during heating and cooling. The method is based on the utilization of the effect of the temperature dependence of emissivity. The method involves the use of relative laser reflectometry which does not require the validity of Lambert's law. The results of measurements of the emissivity of tungsten, rhenium, and tantalum using the suggested pyrometer are given. B-3, 16:20 --
Blackbody Sources within the 100 to 3500K Temperature Range for Precision
Measurements in Radiometry and Thermometry The paper presents the detailed review of blackbodies that are ranged to Low-, Middle-, and High-temperature sources developed at VNIIOFI during more than 25 years. There is a successful record of delivering advanced precision BBs including high temperature BB3200 and BB3500 to major National standard laboratories: NIST (USA), PTB (Germany), NPL (Great Britain), NPL (India), NIM (China) and large-area low- and medium-temperature BBs in other laboratories. B-3, 16:40 --
Low Scatter Optical System for Emittance and Temperature Measurements
The development
and evaluation of an optical system for a new spectral directional emittance
facility at NIST is reported. The imaging quality and signal contributions
due to out-of-field-of-view scattering, commonly characterized by the
"size-of-source effect (SSE)" parameter, have been measured
across the spectral range of 0.65 to 4 microns by three independent
methods. The SSE measurement results of scatter levels not exceeding
2-3 parts in 104 are consistent and exceed the design targets. The potential
application of the optical system to construction of a portable instrument
with low scatter/emission and an operating spectral range of 0.65 to
20 microns are discussed. 15:00 - 17:00 -- Session B-4. Fluorescence and Laser Techniques B-4, 15:00 --
Phosphor Thermometry at ORNL Phosphor materials are, by design, capable of efficiently converting excitation energy into fluorescence. The temperature-dependent characteristics of this fluorescence provide the basis for noncontact thermometry. In the past decade this approach has been applied to turbine engine diagnostics, liquid temperature measurements for heat pump research, combustion engine intake valve and piston measurements, galvanneal steel processing, transient thermometry of particle beam targets, and microcantilevers used in MEMS devices. The temperatures involved range from ambient to in excess of 1200 C. Some of these applications have involved fiber optics for light delivery and/or fluorescence signal collection. In addition to fielding these applications, there has been considerable work in the laboratory aimed at exploring further improvements and adding to the data base of temperature-characterized phosphors. The activities involve investigation of short-decay time phosphors for use on imaging surfaces moving at high speeds, measuring and modeling pressure as well as temperature dependence, developing to phosphor adhesion methods, developing phase-based data acquisition approaches. A significant advance is that light emitting diodes can now be used to provide adequate stimulation of fluorescence in some applications. Recently nanophosphors have become available. The spectral properties and, by implication, thermal dependence of these properties change which particle size. This has ramifications which need to be explored. The ways in which such materials can be exploited for micro- and nano-technology are just now being addressed. These applications and developments mentioned above will be surveyed and discussed as well as envisioned future improvements and new uses for this thermometry technique. B-4, 15:20 --
Ultra High Precision Phosphor Thermometry near 1100 K Using the rare-earth doped phosphor Y2O3:Eu, which has a strong temperature dependent emission near 611 nm beginning around 600 C, we studied the precision with which the fluorescent lifetime followed temperature changes near 800 C. The goal was to investigate the utility of such a material as a temperature standard in this relatively high temperature range. We used a thermal mass of alumina that drifted in temperature predictably following Newton's Law of Cooling, along with a nitrogen-laser (337 nm) excitation system. Our results showed precision near 10 mK, with potential for further improvement. B-4, 15:40 --
A Calibration System for Fluorescence Thermography A temperature reference system for calibrating fluorescence-based sensors was developed. The system is based on a special thermostatic chamber and on an electro-optic system equipped with a fiber-optic scanner. A thin layer of the sensing material to be calibrated can be coated onto a temperature controlled reference surface, which is housed inside the thermostatic chamber. It was designed in such a way as to operate under different conditions (from vacuum to atmospheric pressure) in order to evaluate the effect of the surrounding fluid on the surface temperature measurements. The reference surface can be heated both radially, by a wire wound heater, and axially, by a thermoelectric cooler. Experimental investigations were carried out in the temperature range -50 °C to about 200 °C. The results showed a temperature stability of better than 0.03 °C and a surface temperature uniformity to within 0.02 °C. The system was used to characterize a sensitive phosphor. The phosphor calibration curve was thus obtained, with a single-point repeatability of better than 0.1 °C. The spatial temperature uniformity of the phosphor-coated surface was also investigated by using the built-in fiber-optic scanner in both environments. The results showed a temperature uniformity to within 0.1 °C. B-4, 16:00 Fluorescence
Thermometry in Microfluidics Two techniques
are described for the measurement of fluid temperatures in microfluidic
systems based on temperature-dependent fluorescence. In the first technique,
a single, strongly temperature-dependent fluorophore, rhodamine B, is
used as the basis for fluorescence intensity-based thermometry. For
the second technique, two different fluorophores are used with different
emission wavelengths, and the ratio of the signals at the two different
colors is used to calculate the temperature. Both techniques are easy
to implement with a standard fluorescence microscope and CCD camera.
In addition, the methods can be used to measure fluid temperatures with
micrometer spatial resolution and millisecond time resolution. The methods
are demonstrated by measuring temperature distributions within a variety
of microfluidic devices resulting from either direct contact heating
or Joule heating as fluid is electrokinetically pumped though the systems. 15:00 - 17:00 -- Session B-5. Cryogenic Thermometry: Devices B-5, 15:00 --
Review of Zirconium Oxy-Nitride CernoxTM () Thin Film Resistance Temperature
Sensors CernoxTM resistance thermometers were commercially introduced in 1993. The CernoxTM temperature-sensing element is fabricated from zirconium reactively sputtered in a nitrogen-oxygen atmosphere. The resulting thin film is comprised of conducting zirconium nitride embedded within a zirconium oxide nonconducting matrix. This material has a negative temperature coefficient of resistance making it useful as a temperature sensor. The ratio of conducting to nonconducting material can be varied to tailor the sensor to a given temperature range. A single device can be fabricated for use from below 0.3 K to 420 K. CernoxTM temperature sensors possess many attributes desirable in a temperature sensor including high sensitivity, excellent short-term and long-term stability, small physical size, fast thermal response and small calibration shifts when exposed to magnetic fields or ionizing radiation. This paper presents a review of CernoxTM temperature sensors with regard to their physical, thermometric and operational properties and environmental effects. B-5, 15:20
-- Low-temperature Composite Sapphire -RuO2 Thermometer And Its Application
In Heat Capacity Measurements A new low-temperature composite sapphire - RuO2 thermometers have been studied under magnetic field up to 9 T and temperature down to 0.5 K. For a typical 2 ohm thermometer (at room temperature) with a logarithmic temperature coefficient ~ 3.5 at 2 K, its temperature deviations d T / T for H = 9 T are about 0.5 % and 2 % at 4 K and 2 K respectively. Comparing with the existing low temperature thermometers, RuO2 - and ZrO2 - based thermometers, the thermometers exhibit more advantages in many aspects. A calorimetric sapphire square for the use of heat capacity measurement demonstrates its potential capability to measure film specimens due to its small thermal mass ~10-7 J / K (at 4 K) and fast time response t < 1 ms. B-5, 15:40 --
A New Capacitance Thermometer with Novel Design for Use at Low Temperatures
and High Magnetic Fields A capacitance thermometer made of thin layers of Kapton and copper that is insensitive to high magnetic fields is described. This thermometer can be easily fabricated and the final thermometer is a thin rigid tube that can be easily incorporated into the sample space of most high field cryogenic systems. We have demonstrated that the minimum in capacitance vs. temperature of these thermometers can be moved to progressively lower temperatures even below our base temperature of 20mK by changing the construction parameters of the devices. We present data demonstrating their lack of magnetic field dependence, specific sensitivity, and discuss power dissipation in typical operation. B-5, 16:00 --
Open B-5, 16:20 --
Long-Term Stability of Germanium Resistance Thermometers Doped germanium resistance thermometers (GRTs) have been used as cryogenic thermometers for forty years. GRTs exhibit a negative temperature coefficient of resistance and possess a high sensitivity that allows for sub-millikelvin control at lower temperatures. These devices also exhibit excellent short- and long-term stability and were used to maintain national temperature scales below 30 K until the advent of the rhodium-iron thermometer. Lake Shore Cryotronics uses GRTs, model GR-200A-1000, as the transfer thermometer for temperature calibration below 30 K. A typical GRT working standard is thermally cycled from 1.4 K to 330 K once a week on average. Every six months, to ensure stability and traceability, these working standard GRTs are compared against a set of standards-grade germanium, platinum, and rhodium-iron resistance thermometers calibrated by the National Institute of Standards and Technology in the US and/or the National Physical Laboratory in the UK. These comparisons yield a measure of the long-term stability of these GRTs over a period of years. This paper reports the long-term stability from 1.4 K to 30 K of ten germanium resistance thermometers as a function of time and thermal cycling during their use as working standard thermometers. B-5, 16:40 --
New Paramagnetic Susceptibility Thermometers and Bolometers for Fundamental
Physics Measurements New paramagnetic
susceptibility thermometers have been developed for use in fundamental
physics missions on earth orbit. These devices use a SQUID magnetometer
to measure the variation in the dc magnetization of a thermometric element
that consists of a dilute concentration of either iron or manganese
in a palladium matrix. Near 2.2 K these new MnPd thermometers have demonstrated
a temperature resolution of better than 100 pK per root-Hz and a time
constant of 48 ms when operated with a 50 K/W thermal resistance to
the liquid helium sample. These thermometers have been observed to be
remarkably stable, with a drift of less than 3 fK/s. The observed power
spectral density of the noise from these thermometers is consistent
with separate measurements of the device's time constant and thermal
standoff from the bath. These thermometers will be used within the Critical
Dynamics in Microgravity Experiment, which will study the dynamical
properties of the superfluid transition in 4He with unprecedented precision
as part of the first microgravity fundamental physics mission to the
International Space Station in the year 2005. Recently these PdMn materials
have been made into thin films and microstructures for use in other
studies of quantum liquids, and for use in a new class of bolometers
and radiometers. The sensitivity of these devices has been measured
as a function of the magnetic ion concentration, of the charging magnetic
field strength, and of temperature. A new device is currently under
construction that should achieve a thermal noise level of less than
one pK per root-Hz. This device may prove useful in a new class of ultra-stable
space radiometers for background radiation measurements.
08:30 - 10:30 -- Session C-1. Temperature Scales Below 1 K C-1, 8:30 --
PTB-96: The Ultra-Low Temperature Scale of PTB The temperature scale PTB-96 for the range from 0.9 mK to 1 K is one of the melting-pressure scales, on which the Provisional Low Temperature Scale of 2000, PLTS-2000, is based. The construction and the thermodynamic significance of the PTB-96 are discussed in detail considering the now available comprehensive information including recently obtained experimental data. The thermodynamic significance has been evaluated primarily by means of noise thermometry. The internal consistency has been checked applying platinum NMR (nuclear magnetic resonance) thermometry and CMN (cerous magnesium nitrate) thermometry. Considering the results both of primary noise thermometry and consistency checks, a detailed uncertainty budget is presented. C-1, 8:50 --
The Provisional Low-Temperature Scale from 0.9 mK to 1 K, PLTS-2000 The Provisional Low Temperature Scale from 0.9 mK to 1 K, PLTS-2000, was adopted by the Comité International des Poids et Mesures in October 2000. It is defined using an equation for the melting pressure of 3He over the complete temperature range, and forms an extension of the International Temperature Scale of 1990, ITS-90, below its lower limit of 0.65 K. An internationally-accepted ultra-low temperature scale is needed to provide the basis for reliable thermometry in the temperature range in which commercial dilution refrigerators operate, and at lower temperatures where experiments investigating the thermodynamic properties of 3He and other condensed matter are carried out in many research centres. This paper is a summary of a fuller publication describing the background and derivation of the scale, published in the Journal of Low Temperature Physics, and includes tables of values of melting pressure, pm / MPa, and temperature T2000 / K, and the derivative, dpm /dT in MPa/K. C-1, 9:10 --
Thermodynamic Consistency of the New Ultra-Low Temperature Scale PLTS-2000 The thermodynamic consistency of the temperature scale PLTS-2000 has been checked with new measurements using a noise thermometer, which is supposed to indicate thermodynamic temperature, and a platinum nuclear magnetic resonance thermometer, which is assumed to follow a Curie law. The different results are interpreted in terms of the properties of these thermometers, and with supporting calculations using the specific heats of solid and liquid 3He. On this basis, it is possible to specify uncertainty limits of the scale with respect to thermodynamic temperature. C-1, 9:30 --
European Dissemination Of The Ultra-low Temperature Scale, PLTS-2000 The first phase of the EU collaborative project on sub-kelvin thermometry, 'ULT Dissemination', is nearing completion, leading to the development of several thermometers and devices, and the instrumentation needed to disseminate the new Provisional Low Temperature Scale, PLTS-2000, to users. Principal among these are a current-sensing noise thermometer (CSNT), a CMN thermometer adapted for industrial use, a Coulomb blockade thermometer, a second-sound acoustic thermometer and a superconductive reference device SRD-1000. Several partners have set up 3He melting-pressure thermometers to realise the PLTS-2000, and will check it using Pt-NMR, CMN and other thermometers. The scale, which was formally adopted by the Comité International des Poids et Mesures in October 2000, covers the range of temperature from 1 K down to 0.9 mK, and is defined by an equation for the melting pressure of 3He. The SRD employs novel fabrication and detection techniques with up to 10 samples, and is expected to meet the requirement for fixed points below 1 K, formerly filled by the NIST SRM 767 and 768. Other devices included in the project are ruthenium oxide sensors and a self-contained 3He melting pressure thermometer. This paper reviews the project progress to date and indicates the potential for research, metrological and industrial application of the devices developed. C-1, 9:50 --
The Realization of the Provisional Low Temperature Scale of 2000 at
BNM-INM The lower limit of the International Temperature Scale of 1990 (EIT-90) is 0,65 K. Below this limit, no internationally-accepted scale existed before 2000 when the CIPM, following the CCT recommendations, adopted the Provisional Low Temperature Scale of 2000 (PLTS-2000). This scale is based on the 3He melting curve and spans the range 0,9 mK to 1 K. BNM-INM realized PLTS-2000 throughout the range from 20 mK to 1 K by using absolute pressure measurements. BNM-INM studied in details the uncertainty in temperature measurements due to the absolute pressure measurements, in particular near the minimum of the melting curve. The paper presents the results and the uncertainty budget related to the practical realisation of T2000 at BNM-INM. C-1, 10:10 --
Implementation of PLTS-2000: He-3 Melting Pressure Temperature Scale Department of Physics,
University of Florida, Gainesville, FL 32611-8440, USA 08:30 - 10:30 -- Session C-2. SPRTs: Effects & Errors C-2, 8:30 --
Evaluation of Linear Prediction as a Quality Check in PRT Calibrations
on the Range 0 to 420 °C The observed linear correlation between sets of ratio (W) measurements at ITS-90 fixed points among certain platinum resistance thermometers has led to the proposition that sets of measurement results might be evaluated for consistency using linear prediction. Wire quality and probe construction largely effect the quality of the correlation. Data seems to indicate that the technique is inadequate for identifying subtle calibration errors in the general population of PRT's but may play a role in defending against more extreme anomalies. Certain secondary probes appear to have highly correlated resistance ratio values. A simple technique is given for visual identifying anomalous results from a small set of data. C-2, 8:50 --
Experimental Study of Different Filling Gases on the Stability of Metal-Sheathed
Standard Platinum Resistance Thermometers There is a trade-off between the oxidation effect and element contamination in metal-sheathed standard platinum resistance thermometers (MSPRTs). Excessively high O2 partial pressure causes the platinum sensor to oxidize, and excessively low O2 leads to sensor contamination. The oxygen content in a thermometer may become unknown after a period of operation due to slow oxidation of the metal sheath and consequent loss of oxygen in the MSPRT. This can significantly affect the thermometer's performance. Our recent research has shown that a thermometer may eventually become contaminated due to a deficiency of oxygen surrounding its element. In order to research this phenomenon and improve the stability of MSPRTs, ten MSPRTs were specially manufactured for testing. In this paper, the construction of these MSPRTs is described. A series of experiments and their results are presented. Based on the experiment results, a feasible solution (having the element sealed separately from its sheath) is put forward. This solution can resolve the conflict between the oxidation effect and element contamination and improve the long-term stability of MSPRTs. The Rtp and W(Al) stabilities of the MSPRTs with this new design can be as good as 1 mK and 2 mK respectively after operation at high temperature over 1000 hours. C-2, 09:10 --
On the Criteria of Uniformity of the Temperature Field at Realization
of the Fixed Points of the ITS-90 The basic document on realization of the fixed points of the ITS-90 contains the requirements to uniformity of a temperature field in cell. One of them is a uniformity of a temperature field in cell. It should be £10 mK over the entire length of the sample, as measured in the cell held at a temperature a few Kelvin's below, or above, the phase-transition temperature. And another requirement - the temperature field during freezing plateau should correspond to hydrostatic dependence of the phase-transition temperature on height of metal. If the second requirement about a hydrostatics is understandable, it is confirmation of thermal balance between the thermometer and liquid-solid phases interfaces, first is not proved at all. The researches of temperature fields in cells of different designs and in different furnaces on different thermal modes (lower than temperature melting, in melting metal, on a freezing plateau) have shown groundless of the first criterion. C-2, 9:30 --
Influence of SPRT Self-Heat on Measurement Uncertainty in Fixed Point
Calibration and Calibration by Comparison University of Ljubljana,
Faculty of Electrical Engineering, Laboratory of Metrology and Quality,
Slovenia C-2, 9:10 --
Oxidation of Platinum Resistance Thermometers PRTs were soaked at different temperatures and the resulting changes caused by oxidation and the subsequent dissociation of the formed oxide were observed. The resistance of the unoxidized PRTs remained stable for a few days during soaking at the Zn point. Soaking near 350 °C initiated oxidation, in some PRTs, and then the resistance of the PRTs steadily increased with increasing temperatures up to about 520 °C. Soaking near 520 °C, the resistance of the PRT remained stable, suggesting that the thermal energy "KT" equals the energy that binds oxygen to platinum, at the existing oxygen pressure. At temperatures higher than 520 °C the formed oxide dissociated. The higher the temperature the higher the thermal energy and thus the higher the rate of dissociation. One hour of soaking near the Al point dissociated the oxide that took hundreds of hours to accumulate. Three out of seven PRTs tested however would not oxidize. 08:30 - 10:30 -- Session C-3. Radiation Thermometry: Modeling
The variation of emissivity is a serious problem to cause large temperature errors in radiation thermometry, thus it is critical to get hold of the emissivity for an accurate measurement of temperature. This paper describes the mod | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
