Sample records for chromel

  1. Temperature Control System for Chromel-Alumel Thermocouple

    Nuclear Power Plan Operation Safety needs serious handling on temperature measurement and control. In this report has been done manufacturing Temperature Control System for Chromel-Alumel Thermocouple, accordance to material, equipment and human resource ability in the laboratory. Basic component for the Temperature Control System is LM-741 type of Operation Amplifier, which is functionalized as summer for voltage comparator. Function test for this Control System shown its ability for damping on temperature reference. The Temperature Control System will be implemented on PCB Processing Machine. (author)

  2. Ion microprobe investigation of decalibrated chromel versus alumel thermocouples: a quantitative SIMS analysis using indexed sensitivity factors and oxygen flooding

    Secondary Ion Mass Spectrometry (SIMS) was used to determine why sheathed chromel versus alumel thermocouples decalibrate when exposed to temperatures above 11000C. Two thermocouples, one sheathed in inconel-600 and the other in type 304 stainless steel, were studied. Quantified SIMS data showed that these thermocouples decalibrated because significant alterations in the elemental composition of the chromel and alumel thermoelements occurred. (Auth.)

  3. The use of chromel-alumel thermocouples in high temperature experiments in WAGR

    1. Before the prototype Advanced Gas Cooled Reactor at Windscale (WAGR) was finally shut down at the close of its life in June 1981 a programme of concluding experiments, related to certain safety aspects of the Commercial Advanced Gas Cooled Reactors (CAGR), was completed. As part of that programme, some experiments were performed to examine the behaviour of AGR type stainless steel clad fuel pins under postulated operational fault conditions when the peak temperature of the fuel pin cladding approached near to its melting point (1370 deg. C approximately). With this objective, four WAGR fuel stringers were subjected in turn to either a coolant flow or reactor power induced transient lasting a few minutes and sufficient to raise the peak cladding temperature to approximately 1300 deg. C. These experiments were performed in one of the loop systems installed in WAGR which enabled fuel to be irradiated in the reactor core but within a separate pressure tube containment equipped with its own gas cooling system. Thus the in-loop fuel could be operated under temperature conditions different from the rest of the reactor core. 2. This paper is concerned with the thermocouple installation fitted to the experimental stringers to measure the high coolant gas and fuel pin cladding temperatures encountered during the experiments, the method of collecting and checking the data and the performance of the thermocouples during the experiments

  4. A calorimeter with array detectors

    A 5 x 25 = 125 detector array has been designed for a calorimeter. Each element is consisted of a graphite block and a chromel-alumel. A new '0'-point set up was designed by using the critical temperature of the liquid nitrogen as the '0'-point of the temperature. A FY-1 data acquisition system was used for the detector array. The energy distribution of the electron beam has been measured on large-area diode with the system

  5. Probe Measures Fouling As In Heat Exchangers

    Marner, Wilbur J.; Macdavid, Kenton S.


    Combustion deposits reduce transfer of heat. Instrument measures fouling like that on gas side of heat exchanger in direct-fired boiler or heat-recovery system. Heat-flux probe includes tube with embedded meter in outer shell. Combustion gases flow over probe, and fouling accumulates on it, just as fouling would on heat exchanger. Embedded heat-flow meter is sandwich structure in which thin Chromel layers and middle alloy form thermopile. Users determine when fouling approaches unacceptable levels so they schedule cleaning and avoid decreased transfer of heat and increased drop in pressure fouling causes. Avoids cost of premature, unnecessary maintenance.

  6. Device for measuring the local power in a fuel assembly of a nuclear reactor

    For power measurement in the LWR γ-ray thermometers known from heavy water reactors are applied. For this purpose an elongated rod, preferably from steel of the type 304 L, is used, within which there are the γ-ray thermometers in zones lying one above the other. They use thermoelements consisting of two leads of chromel, a protective covering of inconel, and an intermediate insulating covering of Al2O3 or magnesia. The soldered points of the two leads form the cold and hot junction. The thermometers may also be used for PWR's. (DG)

  7. Experimental study of temperature field at fast reactor subassembly exit under drastic changes of coolant temperature

    Failure conditions due to dangerous increasing in power or flow rate drop are the most hazardous in terms of the rise of thermal stresses. Initial rise in temperature may run to 100 C and more. Sodium temperature at the subassembly inlet is varied according to definite time constant which is equal to fuel pin time constant (about 2 sec), that is below the time constant for massive part of subassembly head (4-10 sec). Thus, variations in sodium temperature are, for subassembly head, almost momentary and bring about maximal thermal stresses. Experiments on transient temperature behavior in subassembly head under thermal impact conditions have been performed on the model. Magnitude of temperature has been measured in two cross sections by chromel-alumel thermocouples bond in the middle of the wall, at its outer surface and in the coolant flow for distance of 3 mm from the wall. To measure temperature difference between middle of the wall and its surface fast differential thermocouples chromel-sodium-potassium have been used

  8. The use of thermocouples which transmute during service in nuclear reactors

    Some current nuclear fuel experiments at CRNL require the use of thermocouples to measure temperatures of up to 22000C under reactor operating conditions. A literature search has shown that transient electrical effects and transmutation of the thermocouple alloys can cause temperature measurement errors of up to +-1% and +-30%, respectively. However, the error due to transient electrical effects can be corrected by making temperature measurements immediately following reactor shutdown. Furthermore it has been shown that transmutation effects can be corrected for by calibrating the high temperature tungsten-rhenium thermocouples against a chromel-alumel thermocouple in a cooler part of the experiment. The use of these techniques is expected to reduce temperature measurement errors to +-2% in the best case. (auth)

  9. Resonant Thermoelectric Nanophotonics

    Mauser, Kelly W; Kim, Seyoon; Fleischman, Dagny; Atwater, Harry A


    Photodetectors are typically based on photocurrent generation from electron-hole pairs in semiconductor structures and on bolometry for wavelengths that are below bandgap absorption. In both cases, resonant plasmonic and nanophotonic structures have been successfully used to enhance performance. In this work, we demonstrate subwavelength thermoelectric nanostructures designed for resonant spectrally selective absorption, which creates large enough localized temperature gradients to generate easily measureable thermoelectric voltages. We show that such structures are tunable and are capable of highly wavelength specific detection, with an input power responsivity of up to 119 V/W (referenced to incident illumination), and response times of nearly 3 kHz, by combining resonant absorption and thermoelectric junctions within a single structure, yielding a bandgap-independent photodetection mechanism. We report results for both resonant nanophotonic bismuth telluride-antimony telluride structures and chromel-alumel...

  10. Electrical resistivity measurements in superconducting ceramics

    Electrical resistivity measurements have been done in (Y, Ba, Cu, O) - and (Y, A1, Ba, Cu, O) - based superconducting ceramics. The sintered specimens were prepared by applying gold electrodes and winding on the non-metalized part with a copper strip to be immersed in liquid nitrogen for cooling. The resistivity measurements have been done by the four-probe method. A copper-constantan or chromel-alumel thermocouple inserted between the specimen and the copper cold finger has been used for the determination of the critical temperature Tc. Details of the experimental set-up and resistivity versus temperature plots in the LNT-RT range for the superconducting ceramics are the major contributions of this communication. (author)

  11. Shale oil combustion

    A 'coutant' carbon steel combustion chamber cooled by water jacket was conslructed to burn diesel fuel and mixlure of shale oil and diesel fuels. During experimental work nir fuel ratio was determined, temperaturces were measured using Chromel/ Almel thermocouple, finally the gasous combustion product analysis was carricd out using gas chromatograph technique. The constructed combustion chamber was operating salisfactory for several hours of continous work. According to the measurements it was found that: the flame temperature of a mixture of diesel and shale oil fuels was greater than the flame temperature of diesel fuel. and the sulfer emissious of a mixture of diesel and shale oil fuels was higher than that of diesel fuel. Calculation indicated that the dry gas energy loss was very high and the incomplete combustion energy loss very small. (author). 23 refs., 35 figs

  12. Electrical resistivity measurements in superconducting ceramics

    Electrical resistivity measurements have been done in (Y,Ba,Cu,O)- and (Y,Al,Ba,Cu,O)-based superconducting ceramics. The sintered specimens were prepared by applying gold electrodes and winding on the non-metalized part with a copper strip to be immersed in liquid nitrogen for cooling. The resistivity measurements have been done by the four-probe method. A copper constantan or chromel-alumel thermocouple inserted between the specimen and the copper cold finger has been used for the determination of the critical temperature Tc. Details of the experimental set-up and resistivity versus temperature plots in the LNT-RT range for the superconducting ceramics are the major contributions of this communication. (author)

  13. An Electromotive Force Measurement System for Alloy Fuels

    Changhu Xing; Colby Jensen; Heng Ban; Robert Mariani; J. Rory Kennedy


    The development of advanced nuclear fuels requires a better understanding of the transmutation and micro-structural evolution of the materials. Alloy fuels have the advantage of high thermal conductivity and improved characteristics in fuel-cladding chemical reaction. However, information on thermodynamic and thermophysical properties is limited. The objective of this project is to design and build an experimental system to measure the thermodynamic properties of solid materials from which the understanding of their phase change can be determined. The apparatus was used to measure the electromotive force (EMF) of several materials in order to calibrate and test the system. The EMF of chromel was measured from 100°C to 800°C and compared with theoretical values. Additionally, the EMF measurement of Ni-Fe alloy was performed and compared with the Ni-Fe phase diagram. The prototype system is to be modified eventually and used in a radioactive hot-cell in the future.

  14. Modelling of the steady state thermal behaviour of a permanent magnet direct current motor with commutator. 3D finite elements study

    Bernard, R.; Glises, R.; Chamagne, D.; Cuchet, D.; Kauffmann, J. M.


    The aim of this work concerns the development and the validation of a thermal steady state model applied to a permanent magnet direct current motor with commutator. The rated power of the machine is 120 W. Design has been realized thanks to the thermal modulus of the computation software with the finite element method Flux3D. It is shown in this work how it is possible to use only the heat equation to simulate the thermal behaviour of the motor. It implies calculating of new fluid conductivities (considering also all thermal modes) by comparison of calculated and experimental temperatures. To realize these 3D modelizations, it is necessary to know and to locate all the losses of the motor which are considered as thermal sources. The experimental temperatures are given by 40 chromel-alumel thermocouples of 100 μm diameter located in the rotor and the stator of the machine. Numerical computations use Dirichlet boundary layer conditions given by an IR camera. Ce travail concerne le développement et la validation d'un modèle de simulation du comportement thermique tridimensionnel en régime permanent d'un moteur électrique de 120 watt à courant continu, à aimants permanents et à collecteur. Le logiciel est développé à partir du code de calculs par éléments finis Flux3D. L'équation de la chaleur modélise l'ensemble des transferts thermiques du moteur. Cela nécessite de recaler certains paramètres fluides par comparaison des températures simulées et expérimentales. Une séparation détaillée des différentes pertes est nécessaire pour obtenir une bonne précision finale. Un banc d'essais thermiques permet d'obtenir à l'aide de 40 thermocouples (chromel-alumel de 100 μm de diamètre) les températures au stator et au rotor. Une caméra thermographique infrarouge donne les conditions aux limites de Dirichlet nécessaires à la modélisation.

  15. Analysis of SONACO axial cooling experiments

    The SONACO test rig contained a sodium-cooled, electrically heated 37-pin bundle. On this rig, a series of forced, mixed and natural convection experiments have been performed with the aim of contributing to the understanding of thermal-hydraulic phenomena and providing data for code validation for a subassembly at decay heat power level with low flow or stagnant coolant. The test section and especially the heater pins were equipped with an extensive number of chromel-alumel thermocouples. In addition, special permanent-magnet probes were used for measuring local velocities. In this paper we give a survey of results from axial cooling experiments, where heat was removed by natural convection to a cooling coil situated in the coolant channel (plenum) above the bundle. The experimental conditions led to turbulent convection with a slowly varying, large scale flow pattern. It is shown that a power tilt in the bundle reduces these fluctuations but does not eliminate them. For the uniformly heated bundle, aglebraic expressions for the average turbulent heat flux as well as for temperature and velocity fluctuations are derived from a second-moments model and compared with experimental data. Furthermore, heat transfer in the plenum and the consequences of the SONACO experiments for the coolability of reactor fuel elements under loss-of-flow conditions are discussed. ((orig.))

  16. Cell integrated multi-junction thermocouple array for solid oxide fuel cell temperature sensing: N+1 architecture

    Ranaweera, Manoj; Kim, Jung-Sik


    Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si - 95:2:2:1 by wt.) and chromel (Ni:Cr - 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

  17. Thermocouple temperature measurements in shock-compressed solids

    The emf produced by 5-μm-thick foil thermocouples when subjected to shock loading was studied over a stress range from 0.5 to 10 GPa. Thermocouples of either copper and constantan or chromel and alumel were embedded in the host materials, polymethyl methacrylate (PMMA), Epon 828 epoxy, single-crystal Al2O3, or vitreous SiO2. The observed emf history rises to a plateau in a period that varied from less than 100 ns for Al2O3 to about 500 ns for PMMA. Temperatures inferred from the constant-voltage portion of the records using standard thermocouple tables (corrected for pressure) compare favorably with calculated temperatures for PMMA and epoxy below 2.0 and 4.5 GPa, respectively. Above these threshold stresses, the observed temperatures increase rapidly with compression, which may indicate an exothermic reaction. Inferred temperatures for the two types of thermocouples are in good agreement. The shape of the response history, and agreement with predicted temperatures for PMMA and epoxy, indicate that the thermocouple and host material come to thermal equilibrium during the transient portion of the response. In the elastic materials Al2O3 and SiO2, the observed temperatures are better correlated with temperatures predicted for shock compression of the thermocouple materials than those predicted for the host materials, indicating that thermal equilibration is not achieved in the available test time

  18. Effect of a gas dissolved in water on burnout

    The effect of the gas content distribution over the steam generating channel cross-section on the burnout in water with the various content of dissolved gas was studied experimentally in a high-pressure stand. Distilled water containing dissolved nitrogen was used as a coolant. A vertical smooth tube of Kh18N10T steel (12 mm in dia., 1.5 mm wall thickness, 880 mm long), heated by the electric current, served as the operating section. The instant of the burnout initiation was registered by four chromel-kopel thermocouples. The main expreriments were carried out with the parameter ranging as follows: 10-18 MPa pressure, 1000-3000 kg/(m2xs) mass rate, 0-3.5 MW/m2 thermal flow, 0.2-0.4 steam content, 30-1700 Nxcm3N2/KgH2O the total gas content. It is stated experimentally that the values of critical heat flux practically coincide at the gas content change from 30 to 1700 Nxcm3N2/KgH2O independently of the methods of gas dissolution in water and the methods of measurements of the gas concentration and steam content x in the critical region

  19. High temperature stabilities of interoxides in the system Fe-Sb-O and their comparison with the interoxides in other M-Sb-O (M=Cr, Ni or Co) systems

    An isothermal section of the phase diagram of the system Fe-Sb-O at 873 K was established by isothermal equilibration and XRD analyses of quenched samples. Two ternary oxides namely FeSb2O4 and FeSbO4 were identified. Making use of the phase diagram, the oxygen potentials of the ternary phases were measured by employing the following solid electrolyte based galvanic cells:(I)Chromel, Mo, Sb, Fe3O4, FeSb2O4|15 CSZ|NiO, Ni, Mo, Chromel(II)Pt, Fe3O4, FeSb2O4, FeSbO4|15 CSZ|air (PO2=0.21 atm), Pt(III)Pt, FeSb2O4, FeSbO4, Sb2O3|15 CSZ|air (PO2=0.21 atm), Ptwhere 15 CSZ stands for ZrO2 stabilized by 15 mol% CaO. The least-squares regression analyses of the emfs of the galvanic cells I, II and III (split into two ranges) measured over the temperature ranges 771-911, 771-921 and 787-981 K, respectively, can be represented by the expressionsEI+/-0.39 (mV)=152.8-0.04728 T (K)EII+/-0.22 (mV)=1010.0-0.4172 T (K)EIIIA+/-0.46 (mV)=870.1-0.3665 T (K)EIIIB+/-0.31 (mV)=809.3-0.2992 T (K)These emf expressions were used to derive the standard Gibbs' energies of formation of FeSb2O4 and FeSbO4 and are given byΔGfo (FeSb2O4)+/-3.5 (kJ mol-1)=-1068.7+0.3561 T (K)ΔGfo (FeSbO4)+/-5.5 (kJ mol-1)=-976.9+0.3289 T (K)The emf of the cell III exhibited a break corresponding to the liquidus temperature of Sb2O3. The cell III was used to assess the internal consistency of ΔGfo (FeSbO4) derived from cell II. The consistency of ΔGfo data for these two interoxides with the relevant tie-lines in Fe-Sb-O system is highlighted. Comparison of iron interoxide stabilities with those of six other interoxides in the systems M-Sb-O where M is Cr, Co or Ni reported earlier in the literature revealed FeSb2O4 to be the most stable interoxide with respect to the equilibrium oxygen dissociation pressure in the corresponding set of coexisting phases. Hence, this interoxide is proposed to substitute Sb2O3 in the auxiliary neutron source of liquid metal cooled fast breeder reactors subject to meeting other

  20. Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

    Stella Crosara Lopes


    Full Text Available The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs of the metals and ceramics. Verabond (VB Ni-Cr-Be alloy, Verabond II (VB2, Ni-Cr alloy, Pors-on 4 (P, Pd-Ag alloy, and IPS (I and Duceram (D ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01 for the MCBS test results (MPa, with PI showing higher MCBS (67.72 than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1 differences were: VBI (0.54, VBD (1.33, VB2I (-0.14, VB2D (0.63, PI (1.84 and PD (2.62. Pearson's correlation test (r=0.17 was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

  1. Relative humidity measurements with thermocouple psychrometer and capacitance sensors

    The relative humidity is one of the important hydrological parameters affecting waste package performance. Water potential of a system is defined as the amount of work required to reversibly and isothermally move an infinitesimal quantity of water from a pool of pure water to that system at the same elevation. The thermocouple psychrometer, which acts as a wet-dry bulb instrument based on the Peltier effect, is used to measure water potential. The thermocouple psychrometer works only for relative humidity greater than 94 percent. Other sensors must be used for drier conditions. Hence, the author also uses a Vaisala Humicap, which measures the capacitance change due to relative humidity change. The operation range of the Humicap (Model HMP 135Y) is from 0 to 100 percent relative humidity and up to 160C (320F) in temperature. A psychrometer has three thermocouple junctions. Two copper-constantan junctions serve as reference temperature junctions and the constantan-chromel junction is the sensing junction. Current is passed through the thermocouple causing cooling of the sensing junction by the Peltier effect. When the temperature of the junction is below the dew point, water will condense upon the junction from the air. The Peltier current is discontinued and the thermocouple output is recorded as the temperature of the thermocouple returns to ambient. The temperature changes rapidly toward the ambient temperature until it reaches the wet bulb depression temperature. At this point, evaporation of the water from the junction produces a cooling effect upon the junction that offsets the heat absorbed from the ambient surroundings. This continues until the water is depleted and the thermocouple temperature returns to the ambient temperature (Briscoe, 1984). The datalogger starts to take data roughly at the wet bulb depression temperature

  2. An Innovative Modeling and Measurement Approach to Improve Rice Water Use Efficiency in California

    Montazar, A.; Little, C.; Rejmanek, H.; Tindula, G.; Snyder, R. L.


    California is amongst the top rice producing states in the USA, and more than 95 percent of California's rice is grown in the Sacramento Valley. Based on older literature, the rice water requirement (ETc), ranges between 914 and 1,100 mm. In this study, the actual rice water requirement was measured using the residual of the energy balance method over three paddy rice fields during 2011-2013 seasons in the Sacramento Valley. Net radiation and ground heat flux density were measured, and both eddy covariance (EC) and the surface renewal (SR) technique were employed to determine the sensible heat flux density. The surface renewal method uses high frequency temperature measurements from fine wire thermocouples above the canopy. Mean amplitude and duration of the ramps over half hour periods were determined using a structure function and the characteristics are employed to estimate the direction and magnitude of sensible heat flux using the ratio of the amplitude to the ramp duration as the change in temperature per unit time and the volumetric heat capacity of the air to estimate the magnitude of the heat flux. In the study, 76.2 mm diameter chromel-constantan thermocouples were used to measure high frequency temperature at 10 Hz. The results indicate that there is considerable variability in rice water use both spatially and temporally. The average three-year measured ET of the experimental fields located in Butte County was 734 and 725 mm; and in Colusa County was 771 mm. A typical crop coefficient (Kc) curve was derived from the measured ETc and reference ET (ETo) data. Spatial estimates of monthly climate data from the Sacramento Valley were used to calculate monthly mean ETo, and smooth curve fits of the monthly data gave estimates of typical daily ETo. The daily ETc was calculated as the product of ETo and Kc, and seasonal ETc was calculated by summing the daily ETc values. The results reveal that the seasonal rice ETc was less than earlier estimates. Surface

  3. U.S. Space Radioisotope Power Systems and Applications: Past, Present and Future

    Cataldo, Robert L.; Bennett, Gary L.


    -1906) and R. J. Strut. Almost 100 years ago, in 1913, English physicist H. G. J. Moseley (1887-1915) constructed the first nuclear battery using a vacuum flask and 20 mCi of radium (Corliss and Harvey, 1964, Proceedings of the Royal Society, 1913). After World War II, serious interest in radioisotope power systems in the U.S. was sparked by studies of space satellites such as North American Aviation s 1947 report on nuclear space power and the RAND Corporation s 1949 report on radioisotope power. (Greenfield, 1947, Gendler and Kock, 1949). Radioisotopes were also considered in early studies of nuclear-powered aircraft (Corliss and Harvey, 1964). In 1951, the U.S. Atomic Energy Commission (AEC) signed several contracts to study a 1-kWe space power plant using reactors or radioisotopes. Several of these studies, which were completed in 1952, recommended the use of RPS. (Corliss and Harvey, 1964). In 1954, the RAND Corporation issued the summary report of the Project Feedback military satellite study in which radioisotope power was considered (Lipp and Salter, 1954, RAND). Paralleling these studies, in 1954, K. C. Jordan and J. H. Birden of the AEC s Mound Laboratory conceived and built the first RTG using chromel-constantan thermocouples and a polonium-210 (210Po or Po-210) radioisotope heat source (see Figure 2). While the power produced (1.8 mWe) was low by today s standards, this first RTG showed the feasibility of RPS. A second thermal battery was built with more Po-210, producing 9.4 mWe. Jordan and Birden concluded that the Po-210 thermal battery would have about ten times the energy of ordinary dry cells of the same mass (Jordan and Birden, 1954). The heat source consisted of a 1-cm-diameter sphere of 57 Ci (1.8 Wt) of Po-210 inside a capsule of nickel-coated cold-rolled steel all inside a container of Lucite. The thermocouples were silver-soldered chromel-constantan. The thermal battery produced 1.8 mWe.

  4. Thermoelectric and photovoltaic effects in metal-semiconductor multilayers; Thermoelektrische und Photovoltaische Effekte in Metall-Halbleiter Multilagenstrukturen

    Kyarad, A.


    In an anisotropic material a heat flux and the resulting thermoelectric field generally are not collinear. Illumination of a thin film can thus lead to transverse thermoelectric voltages: Heat produced at the surface by absorption of light flows perpendicularly to the film plane into a substrate, anisotropy may produce a thermoelectric field component parallel to the film surface leading to a ''transverse'' thermoelectric voltage upon surface heating. Thermoelectric fields transverse to an applied temperature gradient have been observed in tilted metallic multilayer structures. Constantan/chromel/constantan.. multilayers were prepared by sintering stacks of alternating thin foils of these materials. Effective ''in-plane'' and ''out-of-plane'' Seebeck coefficients and heat conductivities of the foil stacks were calculated from data of the isotropic metals. Tilted multilayer structures obtained by cutting stacks obliquely may be used as devices for detection of laser radiation. A comparison is made with respect to responsivity between several multilayer structures and anisotropic crystalline systems. A synthetic material with large thermoelectric anisotropy has been prepared from a metal-semiconductor multilayer structure. By an alloying process, a multilayer stack A-B-A.., where A and B are pure aluminum and n-silicon, is produced with a thermoelectric anisotropy 1.5 mV/K, where and are the absolute Seebeck coefficients along and perpendicular to the layers, respectively. The use of this synthetic material for light sensing applications is demonstrated. Irradiation of an Al-Si multilayer stack with infrared to visible laser radiation generates photovoltaic signals depending on the angle of incidence of the laser beam with respect to the layer planes, with zero signal and a polarity reversal for beam and layers in parallel. Results are explained in terms of photoactive layers connected in series and