| 1. |
- Alm, Ove, et al.
(författare)
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A multiple coaxial wire for pressure calibration
- 1974
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 45:4, s. 594-595
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Tidskriftsartikel (refereegranskat)abstract
- A single wire containing several metals suitable for pressure calibration has been produced by extrusion. Coaxial combinations of Ce-Bi-TI and Ce-Bi-Ba have been prepared by the procedure described.
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| 2. |
- Andersson, Odd E., et al.
(författare)
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Low temperature calibration of Manganin pressure gauges
- 1997
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 68:2, s. 1344-1345
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Tidskriftsartikel (refereegranskat)abstract
- High pressures are often measured using the resistance of Manganin wires. However, the pressure coefficient of resistance is known to depend on temperature. We have measured this temperature dependence by comparing the output from a Manganin gauge with that of a well calibrated Zeranin gauge and determined a correction factor which enables us to measure the pressure at any temperature between 150 and 300 K with a temperature dependent error well below 0.5%.
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| 3. |
- Andersson, Per, et al.
(författare)
-
Electrical resistance of Evanohm under pressure
- 1975
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 46:9, s. 1292-1293
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Tidskriftsartikel (refereegranskat)abstract
- The electrical resistance of Evanohm wire has been determined as a function of hydrostatic pressure. A Teflon cell with a novel type of electrical feedthrough was used to contain the fluid medium. The resistance was found to decrease approximately linearly by 0.3% up to 27 kilobar. The remarkably small variation of its resistance with temperature and pressure makes Evanohm a suitable material for strain measurements under pressure.
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| 4. |
- Andersson, Per, et al.
(författare)
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Thermal conductivity of solids under pressure by the transient hot wire method
- 1976
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 47:2, s. 205-209
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Tidskriftsartikel (refereegranskat)abstract
- An electronic circuit has been constructed which delivers constant power to a nickel wire also functioning as a resistance thermometer. The temperature increase versus time, t, is linear in ln t, and the coefficient of slope directly yields the thermal conductivity of the medium surrounding the wire. Systematic errors due to finite time, wire length, and lateral extension of the medium and due to plastic deformation of the wire are analyzed. Temperatures are sampled automatically, and the digital data are reduced by means of an on-line desk calculator. The thermal conductivities of AgCl and polytetrafluoroethylene have been measured up to 10 kilobar.
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| 5. |
- Andersson, Staffan, et al.
(författare)
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Techniques for determining thermal conductivity and heat capacity under hydrostatic pressure
- 1986
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 57:8, s. 1633-1639
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes a method for measuring the pressure dependence of the thermal conductivity and the heat capacity of hard materials and single crystals. Two parallel metal strips are evaporated onto a flat surface of the specimen, one being used as a heater, the other as a resistance thermometer. The appropriate theoretical expression for a specimen in a liquid medium is fitted to the temperature, sampled at constant time intervals. The thermophysical properties of the liquid high‐pressure medium are taken from hot‐wire experiments. The procedure has been thoroughly tested at atmospheric pressure using an MgO crystal and glass as specimens and liquids of different characteristics in lieu of high‐pressure medium. The accuracy attainable was found to be 3% or better, the standard deviation of the measurements being about 0.3%. The potential of the system was demonstrated by measurements on single‐crystal MgO under pressures up to 1 GPa.
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| 6. |
- Bäckström, Gunnar
(författare)
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Circuitry for ac thermometry and dc heating in measurements of thermal properties
- 1978
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 49:6, s. 864-865
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Tidskriftsartikel (refereegranskat)abstract
- An instrument is described in which the resistance of a metal wire thermometer is measured by an ac bridge and sampled at a fixed rate. A superimposed dc pulse heats the wire during a selectable time interval. The temperature may be recorded before heating, during heating, and during cooling.
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| 7. |
- Cedergren, Magnus, et al.
(författare)
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Strain gauge measurements of volume changes in polymorphic transitions under pressure
- 1972
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 43:4, s. 686-688
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Tidskriftsartikel (refereegranskat)abstract
- A strain gauge wire was wound around a sample of cylindrical shape. One part of the wire was wound around the belly, the other in a plane going through the axis. For a certain choice of the turn ratio and the length-to-diameter ratio the strain could be made proportional to ΔV. From tests performed on Bi, it appears that ΔV / Vo approximately 2 x 10-4 may be detected with the present method. No volume discontinuity corresponding to the phase transition at 43 kilobar reported by Bridgman was observed.
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| 8. |
- Chadi, Abd Alrahman, et al.
(författare)
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Note : Simple and compact piezoelectric mirror actuator with 100 kHz bandwidth, using standard components
- 2013
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 84:5, s. 056112-
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Tidskriftsartikel (refereegranskat)abstract
- We propose a mounting scheme to control the displacement of a mirror (or other small object) by a cylindrical piezoelectric actuator, giving uniform response and no phase lag up to high frequencies. This requires a simple ring holder, and unmodified off-the-shelf components. In our implementation, the piezo-mirror assembly has its first mechanical resonance around 120 kHz, close to the resonance for the bare piezo. The idea is to decouple the fundamental elongation mode of the piezo-mirror assembly from the holder by side-clamping the assembly at its zero-displacement plane for this mode. The main drawback is a reduced mirror displacement, by a factor 2 in our case (mirror displacement is similar to 2.5 mu m). Also, the mirror needs to be light with respect to the piezo: still, we use a standard half-inch mirror. The resulting system is very compact as it fits inside a 1-in. commercial steering mirror post.
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| 9. |
- Forsberg, Christer, et al.
(författare)
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Principle, calibration, and application of the in situ alkali chloride monitor
- 2009
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 80:2, s. 023104-1-023104-4
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Tidskriftsartikel (refereegranskat)abstract
- The extended use of biomass for heat and power production has caused increased operational problems with fouling and high-temperature corrosion in boilers. These problems are mainly related to the presence of alkali chlorides (KCl and NaCl) at high concentrations in the flue gas. The In-Situ Alkali Chloride Monitor (IACM) was developed by Vattenfall Research and Development AB for measuring the alkali chloride concentration in hot flue gases (>650 oC). The measurement technique is based on molecular differential absorption spectroscopy in the UV range. Simultaneous measurement of SO2 concentration is also possible. The measuring range is 1-50 ppm for the sum of KCl and NaCl concentrations, and 4-750 ppm for SO2. This paper describes the principle of the IACM as well as its calibration. Furthermore, an example of its application in an industrial boiler is given.
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| 10. |
- Håkansson, Björn, et al.
(författare)
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Improved hot-wire procedure for thermophysical measurements under pressure
- 1988
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 59:10, s. 2269-2275
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Tidskriftsartikel (refereegranskat)abstract
- A new and simplified version of the circuitry for the transient hot‐wire method is presented. The circuitry provides a wide range of currents allowing probe wires of various diameters to be used in order to match the thermal properties of the specimen to be investigated. The analysis of the temperature increase during the heat pulse is based on the exact solution for a heated wire immersed in a medium. Data are corrected for varying power. The method was tested by computer simulations and by measurements of the thermal conductivity (λ) and the heat capacity per unit volume (ρcp ) of glycerol at room temperature and atmospheric pressure, and for CsCl and NaCl at room temperature and at pressures up to 2 GPa. The results on glycerol and CsCl are in excellent agreement with previous works. The inaccuracy in λ and ρcp is estimated as 1%–2% and 3%–5%, respectively, but the standard deviation of the measurements is as low as 0.2% for λ and 1% for ρcp. The improved procedure makes it possible to detect systematic errors caused by reflection of the heat pulse from the walls of the high‐pressure cell. This error, which reveals itself by a curvature of the residual, defined as the difference between fitted function and data, was demonstrated in the case of NaCl. A theoretical estimate of the influence of perturbations due to reflection was also carried out and it was found that the error mainly affects the value of ρcp.
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