Oxidation-resisting technology of W-Re thermocouples and their industrial applications

NASA Astrophysics Data System (ADS)

Wang, K.; Dai, M.; Dong, J.; Wang, L.; Wang, T.

2013-09-01

We use DSC/TG, SEM and EPMA approaches to investigate the high temperature oxidation behaviors of the Type C W-Re thermocouple wires and W-Re powders which the wires were made from. To solve the oxidization of W-Re thermocouples the chemical method, other than the commonly used physical method, i.e. vacuum-pumping method, was developed. Several solid-packed techniques such as stuffing with inert material, chemical deoxidizing, gas-absorbing and sealing were employed to prevent the W-Re thermocouples from oxidizing. Based on comprehensive consideration of various parameters in process industries, a series of industrial W-Re thermocouples has been successfully used in oxidizing and reducing atmospheres, high temperature alkali and other harsh environments. The service life is 6 to 12 months in strong oxidizing atmosphere of Cr2O3-Al2O3 brick kiln and 2 to 3 months in high temperature alkali and in reducing atmosphere of CO.

Microhotplate Temperature Sensor Calibration and BIST.

PubMed

Afridi, M; Montgomery, C; Cooper-Balis, E; Semancik, S; Kreider, K G; Geist, J

2011-01-01

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the silicon substrate temperature if never exposed to temperatures above about 220 °C.

Real-time temperature monitoring with fiber Bragg grating sensor during diffuser-assisted laser-induced interstitial thermotherapy.

PubMed

Pham, Ngot Thi; Lee, Seul Lee; Park, Suhyun; Lee, Yong Wook; Kang, Hyun Wook

2017-04-01

High-sensitivity temperature sensors have been used to validate real-time thermal responses in tissue during photothermal treatment. The objective of the current study was to evaluate the feasible application of a fiber Bragg grating (FBG) sensor for diffuser-assisted laser-induced interstitial thermotherapy (LITT) particularly to treat tubular tissue disease. A 600 - ? m core-diameter diffuser was employed to deliver 980-nm laser light for coagulation treatment. Both a thermocouple and a FBG were comparatively tested to evaluate temperature measurements in ex vivo liver tissue. The degree of tissue denaturation was estimated as a function of irradiation times and quantitatively compared with light distribution as well as temperature development. At the closer distance to a heat source, the thermocouple measured up to 41% higher maximum temperature than the FBG sensor did after 120-s irradiation (i.e., 98.7 ° C ± 6.1 ° C for FBG versus 131.0 ° C ± 5.1 ° C for thermocouple; p < 0.001 ). Ex vivo porcine urethra tests confirmed the real-time temperature measurements of the FBG sensor as well as consistently circumferential tissue denaturation after 72-s irradiation ( coagulation thickness = 2.2 ± 0.3 ?? mm ). The implementation of FBG can be a feasible sensing technique to instantaneously monitor the temperature developments during diffuser-assisted LITT for treatment of tubular tissue structure.

Temperature increasing in titanium implants using a high-intensity diode laser for peri-implantitis decontamination

NASA Astrophysics Data System (ADS)

Faustino, C. N.; Ana, A. P.; Bachman, L.

2018-02-01

Peri-implantitis is a destructive inflammatory process that affects the tissues that provide support to the dental implant, the bone and gingiva, and can lead to the loss of the implant. Among the treatments of this disease, the irradiation of the contaminated surface with high intensity lasers is considered a promising alternative; Thus, irradiation parameters must be correctly adjusted in order to promote an efficient and safe treatment. This study investigated the temperature changes at the implant-bone interface during simulated implant surface decontamination using an 808nm diode laser. Dental implants were inserted in bovine bone, in which an artificial periimplant bone defect was made. Access holes of 0.5mm diameter were drilled to allow the positioning of four Ktype thermocouples in different regions: T0 Implant-bone interface, T1 inside the implant, T2 In the bone defect, T3 In the apex of the implant. For laser irradiation, an optical fiber was used at a distance of 0.5mm from the implant surface, and the mean output power varied between 0.5 to 3.0W on both pulsed (PW) and continuous (CW) wave modes. Irradiations were performed by 60s, and the temperature rises were registered for a period of 180s. It was observed that the critical threshold of 47ºC was exceeded at T0, T1 e T2 thermocouples when irradiations were performed at 1.0W; for T3 thermocouple, the threshold was exceeded at 3.0W CW mode. For PW mode, the thermocouples T0, T1, T2 had the threshold exceeded at the power of 1,0W and for T3 the threshold was exceeded at 3.0W. Decontamination of implant surfaces using the diode laser did not excessively heat the implant-bone interface within the mean output power ranging from 0.5 to 1.0W; however, the temperature rise is critical when using the mean power of 0.5W CW and 1.0W PW. Thus, using the PW mode up to the power of 1W seems to be a promising parameter for a safe clinical application.

In situ temperature measurements with thermocouple probes during laser interstitial thermotherapy (LITT): quantification and correction of a measurement artifact.

PubMed

Manns, F; Milne, P J; Gonzalez-Cirre, X; Denham, D B; Parel, J M; Robinson, D S

1998-01-01

The purpose of this work was to quantify the magnitude of an artifact induced by stainless steel thermocouple probes in temperature measurements made in situ during experimental laser interstitial thermo-therapy (LITT). A procedure for correction of this observational error is outlined. A CW Nd:YAG laser system emitting 20W for 25-30 s delivered through a fiber-optic probe was used to create localized heating. The temperature field around the fiber-optic probe during laser irradiation was measured every 0.3 s in air, water, 0.4% intralipid solution, and fatty cadaver pig tissue, with a field of up to fifteen needle thermocouple probes. Direct absorption of Nd:YAG laser radiation by the thermocouple probes induced an overestimation of the temperature, ranging from 1.8 degrees C to 118.6 degrees C in air, 2.2 degrees C to 9.9 degrees C in water, 0.7 C to 4.7 C in intralipid and 0.3 C to 17.9 C in porcine tissue after irradiation at 20W for 30 s and depending on the thermocouple location. The artifact in porcine tissue was removed by applying exponential and linear fits to the measured temperature curves. Light absorption by thermocouple probes can induce a significant artifact in the measurement of laser-induced temperature increases. When the time constant of the thermocouple effect is much smaller than the thermal relaxation time of the surrounding tissue, the artifact can be accurately quantified. During LITT experiments where temperature differences of a few degrees are significant, the thermocouple artifact must be removed in order to be able accurately to predict the treatment outcome.

Design of thermocouple probes for measurement of rocket exhaust plume temperatures

NASA Astrophysics Data System (ADS)

Warren, R. C.

1994-06-01

This paper summarizes a literature survey on high temperature measurement and describes the design of probes used in plume measurements. There were no cases reported of measurements in extreme environments such as exist in solid rocket exhausts, but there were a number of thermocouple designs which had been used under less extreme conditions and which could be further developed. Tungsten-rhenium(W-Rh) thermocouples had the combined properties of strength at high temperatures, high thermoelectric emf, and resistance to chemical attack. A shielded probe was required, both to protect the thermocouple junction, and to minimise radiative heat losses. After some experimentation, a twin shielded design made from molybdenum gave acceptable results. Corrections for thermal conduction losses were made based on a method obtained from the literature. Radiation losses were minimized with this probe design, and corrections for these losses were too complex and unreliable to be included.

DOE Office of Scientific and Technical Information (OSTI.GOV)

K. L. Davis; J. L. Rempe; D. L. Knudson

Silicon carbide (SiC) temperature monitors 05R4-02-A KG1403 (300 LO) and 05R4-01-A KG1415 (400 LO B) were evaluated at the High Temperature Test Lab (HTTL) to determine their peak irradiation temperatures. HTTL measurements indicate that the peak irradiation temperature for the 300 LO monitor was 295 {+-} 20 C and the peak irradiation temperature for the 400 LO B monitor was 294 {+-} 25 C. Two silicon carbide (SiC) temperature monitors irradiated in the Advanced Test Reactor (ATR) were evaluated at the High Temperature Test Lab (HTTL) to determine their peak temperature during irradiation. These monitors were irradiated as part ofmore » the University of Wisconsin Pilot Project with a target dose of 3 dpa. Temperature monitors were fabricated from high density (3.203 g/cm3) SiC manufactured by Rohm Haas with a nominal size of 12.5 mm x 1.0 mm x 0.75 mm (see Attachment A). Table 1 provides identification for each monitor with an expected peak irradiation temperature range based on preliminary thermal analysis (see Attachment B). Post irradiation calculations are planned to reduce uncertainties in these calculated temperatures. Since the early 1960s, SiC has been used as a post-irradiation temperature monitor. As noted in Reference 2, several researchers have observed that neutron irradiation induced lattice expansion of SiC annealed out when the post-irradiation annealing temperature exceeds the peak irradiation temperature. As noted in Reference 3, INL uses resistivity measurements to infer peak irradiation temperature from SiC monitors. Figure 1 depicts the equipment at the HTTL used to evaluate the SiC monitors. The SiC monitors are heated in the annealing furnace using isochronal temperature steps that, depending on customer needs, can range from 50 to 800 C. This furnace is located under a ventilation hood within the stainless steel enclosure. The ventilation system is activated during heating so that any released vapors are vented through this system. Annealing temperatures are recorded using a National Institute of Standards and Technology (NIST) traceable thermocouple inserted into an alumina tube in the furnace. After each isochronal annealing, the specimens are placed in a specialized fixture located in the constant temperature chamber (maintained at 30 C) for a minimum of 30 minutes. After the 30 minute wait time, each specimen's resistance is measured using the specialized fixture and a calibrated DC power analyzer. This report discusses the evaluation of the SiC monitors and presents the results. Testing was conducted in accordance with Reference 3. Sections 2 and 3 present the data collected for each monitor and provide interpretation of the data. Section 4 presents the evaluated temperature results.« less

Microhotplate Temperature Sensor Calibration and BIST

PubMed Central

Afridi, M.; Montgomery, C.; Cooper-Balis, E.; Semancik, S.; Kreider, K. G.; Geist, J.

2011-01-01

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the silicon substrate temperature if never exposed to temperatures above about 220 °C. PMID:26989603

Thermodynamic effects of laser irradiation of implants placed in bone: an in vitro study.

PubMed

Leja, Chris; Geminiani, Alessandro; Caton, Jack; Romanos, Georgios E

2013-11-01

Lasers have been proposed for various applications involving dental implants, including uncovering implants and treating peri-implantitis. However, the effect of laser irradiation on the implant surface temperature is only partially known. The aim of this pilot study was to determine the effect of irradiation with diode, carbon dioxide, and Er:YAG lasers on the surface temperature of dental implants placed in bone, in vitro. For this study, one dental implant was placed in a bovine rib. A trephine bur was used to create a circumferential defect to simulate peri-implantitis, and thermocouples were placed at the coronal and apical aspect of the implant. The implant was irradiated for 60 s using four different lasers independently and change in temperature as well as time to reach a 10 °C increase in temperature were recorded. There was wide variability in results among the lasers and settings. Time for a 10 °C increase ranged from 0.9 to over 60 s for the coronal thermocouple and from 18 to over 60 s for the apical thermocouple. Maximum temperature ranged from 5.9 to 70.9 °C coronally and from 1.4 to 23.4 °C apically. During laser irradiation of dental implants, a surface temperature increase beyond the "critical threshold" of 10 °C can be reached after only 18 s.

Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

PubMed

Chen, Wenhao; Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A; Kumagai, Kazukiyo

2018-01-01

To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices' ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating.

Measurement of heating coil temperature for e-cigarettes with a “top-coil” clearomizer

PubMed Central

Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A.; Kumagai, Kazukiyo

2018-01-01

Objectives To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a “top-coil” clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. Methods The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3–6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). Results For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such “top-coil” clearomizers. Conclusions This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices’ ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating. PMID:29672571

Temperature stabilized effusion cell evaporation source for thin film deposition and molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Tiedje, H. F.; Brodie, D. E.

2000-05-01

A simple effusion cell evaporation source for thin film deposition and molecular-beam epitaxy is described. The source consists of a crucible with a thermocouple temperature sensor heated by a resistive crucible heater. Radiation heat transfer from the crucible to the thermocouple produces a consistent and reproducible thermocouple temperature for a given crucible temperature, without direct contact between the thermocouple and the crucible. The thermocouple temperature is somewhat less than the actual crucible temperature because of heat flow from the thermocouple junction along the thermocouple lead wires. In a typical case, the thermocouple temperature is 1007 °C while the crucible is at 1083 °C. The crucible temperature stability is estimated from the measured sensitivity of the evaporation rate of indium to temperature, and the observed variations in the evaporation rate for a fixed thermocouple temperature. The crucible temperature peak-to-peak variation over a one hour period is 1.2 °C. Machined molybdenum crucibles were used in the indium and copper sources for depositing CuInSe2 thin films for solar cells.

A two-thermocouple probe technique for estimating thermocouple time constants in flows with combustion: In situ parameter identification of a first-order lag system

NASA Astrophysics Data System (ADS)

Tagawa, M.; Shimoji, T.; Ohta, Y.

1998-09-01

A two-thermocouple probe, composed of two fine-wire thermocouples of unequal diameters, is a novel technique for estimating thermocouple time constants without any dynamic calibration of the thermocouple response. This technique is most suitable for measuring fluctuating temperatures in turbulent combustion. In the present study, the reliability and applicability of this technique are appraised in a turbulent wake of a heated cylinder (without combustion). A fine-wire resistance thermometer (cold wire) of fast response is simultaneously used to provide a reference temperature. A quantitative and detailed comparison between the cold-wire measurement and the compensated thermocouple ones shows that a previous estimation scheme gives thermocouple time constants smaller than appropriate values, unless the noise in the thermocouple signals is negligible and/or the spatial resolution of the two-thermocouple probe is sufficiently high. The scheme has been improved so as to maximize the correlation coefficient between the two compensated-thermocouple outputs. The improved scheme offers better compensation of the thermocouple response. The present approach is generally applicable to in situ parameter identification of a first-order lag system.

Experimental system for in-situ measurement of temperature rise in animal tissue under exposure to acoustic radiation force impulse.

PubMed

Nitta, Naotaka; Ishiguro, Yasunao; Sasanuma, Hideki; Taniguchi, Nobuyuki; Akiyama, Iwaki

2015-01-01

Acoustic radiation force impulse (ARFI) has recently been used for tissue elasticity measurement and imaging. On the other hand, it is predicted that a rise in temperature occurs. In-situ measurement of temperature rise in animal experiments is important, yet measurement using thermocouples has some problems such as position mismatch of the temperature measuring junction of the thermocouple and the focal point of ultrasound. Therefore, an in-situ measurement system for solving the above problems was developed in this study. The developed system is composed mainly of an ultrasound irradiation unit including a custom-made focused transducer with a through hole for inserting a thin-wire thermocouple, and a temperature measurement unit including the thermocouple. The feasibility of the developed system was evaluated by means of experiments using a tissue-mimicking material (TMM), a TMM containing a bone model or a chicken bone, and an extracted porcine liver. The similarity between the experimental results and the results of simulation using a finite element method (FEM) implied the reasonableness of in-situ temperature rise measured by the developed system. The developed system will become a useful tool for measuring in-situ temperature rise in animal experiments and obtaining findings with respect to the relationship between ultrasound irradiation conditions and in-situ temperature rise.

Cu, Ag, Au: Electrical Resistivity Along their Melting Boundaries

NASA Astrophysics Data System (ADS)

Secco, R.; Littleton, J. A. H.; Berrada, M.; Ezenwa, I.; Yong, W.

2017-12-01

Electrical resistivity of Cu, Ag and Au was measured at pressures up to 5 GPa and temperatures up to 300 K above melting in a 1000-ton cubic anvil press. Two W/Re thermocouples placed at opposite ends of the wire sample served as T probes as well as 4-wire resistance electrodes in a switched circuit. A polarity switch was also used to remove any bias associated with current flow and voltage measurement using thermocouple legs. Examination of the composition of recovered and sectioned samples was carried out using electron microprobe analyses. Melting temperatures at high pressures were determined from the large jump in resistivity on heating at constant pressure and these agree well with previous experimental and theoretical phase diagram studies. With increasing P and T, electrical resistivity behavior in these noble metals is consistent with 1atm data. The resistivity values at the melting temperature of Cu and Ag decrease with increasing high pressure and Au seems to behave similarly. The results are compared to prediction by Stacey and Anderson (PEPI, 2001).

Thermal effects in photomask engineering and nano-thermometry

NASA Astrophysics Data System (ADS)

Chu, Dachen

Electron Beam Lithography (EBL) in photomask fabrication results in heating of the resist films. The local heating can change the chemical properties of resist, leading to placement errors. The heating induced error has been believed to be increasingly significant as the transistor minimum feature size approaches the sub 100 nm region. A Green's function approach has been developed to calculate four-dimensional temperature profiles in complex structures such as the multi-layer work-pieces being exposed in EBL. The model is being used to characterize different ebeam writing strategies to find the optimum. To provide the parameters for the model, two independent techniques have been employed: a thin film electrode method and a laser thermal-reflectance method. Unlike earlier results from polyimide films, no appreciable anisotropy was observed in thermal conductivities for the polymeric resists tested. Gold/nickel thin film thermocouples with minimum junction area of 100nm by 100nm were fabricated and calibrated. These thermocouple demonstrated a 400ns response time when heated by a 10ns laser pulse. Using these nano thermocouples, transient resist heating temperature profiles were for the first time measured at room temperature. Experimental results showed a good agreement with the Green's function model. We also observed a tradeoff in the scaling of thermocouple sensors. The smaller thermocouples may provide higher spatial and temporal resolutions but have poorer temperature resolution. In conclusion, we both modeled and measured the resist heating in EBL. In short exposure time (˜1us or less) the resist heating is nearly adiabatic, while in longer time the heating is dominated by substrate. Nano scale metallic thermocouples were explored and tradeoff was observed in dimension scaling.

Silicon Carbide Temperature Monitor Processing Improvements. Status Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unruh, Troy Casey; Daw, Joshua Earl; Ahamad Al Rashdan

2016-01-29

Silicon carbide (SiC) temperature monitors are used as temperature sensors in Advanced Test Reactor (ATR) irradiations at the Idaho National Laboratory (INL). Although thermocouples are typically used to provide real-time temperature indication in instrumented lead tests, other indicators, such as melt wires, are also often included in such tests as an independent technique of detecting peak temperatures incurred during irradiation. In addition, less expensive static capsule tests, which have no leads attached for real-time data transmission, often rely on melt wires as a post-irradiation technique for peak temperature indication. Melt wires are limited in that they can only detect whethermore » a single temperature is or is not exceeded. SiC monitors are advantageous because a single monitor can be used to detect for a range of temperatures that occurred during irradiation. As part of the process initiated to make SiC temperature monitors available at the ATR, post-irradiation evaluations of these monitors have been previously completed at the High Temperature Test Laboratory (HTTL). INL selected the resistance measurement approach for determining irradiation temperature from SiC temperature monitors because it is considered to be the most accurate measurement. The current process involves the repeated annealing of the SiC monitors at incrementally increasing temperature, with resistivity measurements made between annealing steps. The process is time consuming and requires the nearly constant attention of a trained staff member. In addition to the expensive and lengthy post analysis required, the current process adds many potential sources of error in the measurement, as the sensor must be repeatedly moved from furnace to test fixture. This time-consuming post irradiation analysis is a significant portion of the total cost of using these otherwise inexpensive sensors. An additional consideration of this research is that, if the SiC post processing can be automated, it could be performed in an MFC hot cell, further reducing the time and expense of lengthy decontaminations prior to processing. Sections of this report provide a general description of resistivity techniques currently used to infer peak irradiation temperature from silicon carbide temperature monitors along with some representative data, the proposed concepts to improve the process of analyzing irradiated SiC temperature monitors, the completed efforts to prove the proposed concepts, and future activities. The efforts detailed here succeeded in designing and developing a real-time automated SiC resistivity measurement system, and performed two initial test runs. Activities carried out include the assembly and integration of the system hardware; the design and development of a preliminary monitor fixture; the design of a technique to automate the data analysis and processing; the development of the communication, coordination, and user software; and the execution and troubleshooting of test run experiments using the box furnace. Although the automation system performed as required, the designed fixture did not succeed in establishing the needed electrical contacts with the SiC monitor.« less

Post-irradiation examinations of THERMHET composite fuels for transmutation

NASA Astrophysics Data System (ADS)

Noirot, J.; Desgranges, L.; Chauvin, N.; Georgenthum, V.

2003-07-01

The thermal behaviour of composite targets dedicated to minor actinide transmutation was studied using THERMHET (thermal behaviour of heterogeneous fuel) irradiation in the SILOE reactor. Three inert matrix fuel designs were tested (macro-mass, jingle and microdispersion) all with a MgAl 2O 4 spinel inert matrix and around 40% weight of UO 2 to simulate minor actinide inclusions. The post-irradiation examinations led to a new interpretation of the temperature measurement by thermocouples located in the central hole of the pellets. A major change in the micro-dispersed structure was detected. The examinations enabled us to understand the behaviour of the spinel during the different stages of irradiation. They revealed an amorphisation at low temperature and then a nano re-crystallisation at high temperature of the spinel in the micro-dispersed case. These results, together with those obtained in the MATINA irradiation of an equivalent structure, show the importance of the irradiation temperature on spinel behaviour.

IRRADIATION-CAPSULE STUDY OF URANIUM MONOCARBIDE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, R.B.; Stahl, D.; Stang, J.H.

1960-03-01

Small cylindrical specimens of enriched UC were irradiated to evaluate usefulness as a high-temperature fuel for stationary power reactors. Detailed thermal and nuclear analyses were made to arrive at an appropriate capsule design on the basis of target specimen center-line temperature ( approximately 1500 deg F), specimen surface temperature (1100 deg F), specimen composition (U--5 wt.% C), and acapsule o.d. of 1.125 in. Temperature data from thermocouples inside the capsule indicated that five of the six capsules irradiated operated at close to the design conditions. Irradiation periods for individual capsules were varied to give burnups ranging from 1,000 to 20,000more » Mwd/t of U. Preliminary evidence indicates that this range of burnups was achieved. By using temperature and heat-flux data from the actual irradiations to estimate effective in-pile specimen thermal conductivities, it was found that the conductivity did not appear to vary during the exposures. (auth)« less

[Influence of implants on human body during MRI examinations: fundamental experiment using metal balls].

PubMed

Muranaka, Hiroyuki; Nakamura, Osamu; Usui, Shuji; Ueda, Yoshitake; Morikawa, Kaoru

2005-07-20

It is increasingly the case that patients who have implants feel pain during high-field MRI examinations. A probable reason for the pain is the generation by irradiation of RF pulses and changing of the magnetic field gradient. As a fundamental study on the effect of implants on the human body under MRI procedures, temperature measurements were obtained from metal balls incorporated into gel-filled phantoms by using two kinds of measuring instruments, a copper-constantan thermocouple and a fluorescence fiber thermometer. At first we pursued a correlation between a copper-constantan thermocouple (absolute measurement) and fluoroptic thermometer and confirmed the precision and stability of the fluoroptic thermometer under MRI procedures. When a stainless steel ball with or without a loop antenna was used, only in the former case did the temperature rise during RF pulse irradiation. There was no significant difference between the magnetic field gradient ON and OFF. Furthermore, differences in metal (steel, aluminum, brass, stainless steel, copper) and size (5, 10, 20 mmPhi) were affected according to the increase of temperature. In conclusion, both RF pulse irradiation and a loop antenna are necessary for heat generation on the surface of metals.

High-temperature thermocouples and related methods

DOEpatents

Rempe, Joy L [Idaho Falls, ID; Knudson, Darrell L [Firth, ID; Condie, Keith G [Idaho Falls, ID; Wilkins, S Curt [Idaho Falls, ID

2011-01-18

A high-temperature thermocouple and methods for fabricating a thermocouple capable of long-term operation in high-temperature, hostile environments without significant signal degradation or shortened thermocouple lifetime due to heat induced brittleness.

Joint tests at INL and CEA of a transient hot wire needle probe for in-pile thermal conductivity measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daw, J.E.; Knudson, D.L.; Villard, J.F.

2015-07-01

Thermal conductivity is a key property that must be known for proper design, testing, and deployment of new fuels and structural materials in nuclear reactors. Thermal conductivity is highly dependent on the physical structure, chemical composition, and the state of the material. Typically, thermal conductivity changes that occur during irradiation are currently measured out-of-pile using a 'cook and look' approach. But repeatedly removing samples from a test reactor to make measurements is expensive, has the potential to disturb phenomena of interest, and only provides understanding of the sample's end state when each measurement is made. There are also limited thermo-physicalmore » property data available for advanced fuels; and such data are needed for simulation codes, the development of next generation reactors, and advanced fuels for existing nuclear plants. Being able to quickly characterize fuel thermal conductivity during irradiation can improve the fidelity of data, reduce costs of post-irradiation examinations, increase understanding of how fuels behave under irradiation, and confirm or improve existing thermal conductivity measurement techniques. This paper discusses efforts to develop and evaluate an innovative in-pile thermal conductivity sensor based on the transient hot wire thermal conductivity method (THWM), using a single needle probe (NP) containing a line heat source and thermocouple embedded in the fuel. The sensor that has been designed and manufactured by the Idaho National Laboratory (INL) includes a unique combination of materials, geometry, and fabrication techniques that make the hot wire method suitable for in-pile applications. In particular, efforts were made to minimize the influence of the sensor and maximize fuel hot-wire heating. The probe has a thermocouple-like construction with high temperature resistant materials that remain ductile while resisting transmutation and materials interactions. THWM-NP prototypes were fabricated for both room temperature proof-of-concept evaluations and high temperature testing. Evaluations have been performed jointly by the INL and the French Alternative Energies and Atomic Energy Commission (CEA), both in Idaho Falls (USA) and in Cadarache (France), in the framework of a collaborative program for instrumentation of Material Testing Reactors. Initial tests were conducted on samples with a large range of thermal conductivities and temperatures ranging from 20 deg. C to 600 deg. C. Particularly, tests were recently performed on a sample having thermal conductivity and dimensions similar to UO{sub 2} and MOX nuclear fuels, in order to validate the ability of this sensor to operate for in-pile characterization of Light Water Reactors fuels. The results of the tests already completed at INL and CEA indicate that the Transient Hot Wire Needle Probe offers an enhanced method for in-pile detection of thermal conductivity. (authors)« less

Temperature distribution in target tumor tissue and photothermal tissue destruction during laser immunotherapy

NASA Astrophysics Data System (ADS)

Doughty, Austin; Hasanjee, Aamr; Pettitt, Alex; Silk, Kegan; Liu, Hong; Chen, Wei R.; Zhou, Feifan

2016-03-01

Laser Immunotherapy is a novel cancer treatment modality that has seen much success in treating many different types of cancer, both in animal studies and in clinical trials. The treatment consists of the synergistic interaction between photothermal laser irradiation and the local injection of an immunoadjuvant. As a result of the therapy, the host immune system launches a systemic antitumor response. The photothermal effect induced by the laser irradiation has multiple effects at different temperature elevations which are all required for optimal response. Therefore, determining the temperature distribution in the target tumor during the laser irradiation in laser immunotherapy is crucial to facilitate the treatment of cancers. To investigate the temperature distribution in the target tumor, female Wistar Furth rats were injected with metastatic mammary tumor cells and, upon sufficient tumor growth, underwent laser irradiation and were monitored using thermocouples connected to locally-inserted needle probes and infrared thermography. From the study, we determined that the maximum central tumor temperature was higher for tumors of less volume. Additionally, we determined that the temperature near the edge of the tumor as measured with a thermocouple had a strong correlation with the maximum temperature value in the infrared camera measurement.

Thermal effects in tissues induced by interstitial irradiation of near infrared laser with a cylindrical diffuser

NASA Astrophysics Data System (ADS)

Le, Kelvin; Johsi, Chet; Figueroa, Daniel; Goddard, Jessica; Li, Xiaosong; Towner, Rheal A.; Saunders, Debra; Smith, Nataliya; Liu, Hong; Hode, Tomas; Nordquist, Robert E.; Chen, Wei R.

2011-03-01

Laser immunotherapy (LIT), using non-invasive laser irradiation, has resulted in promising outcomes in the treatment of late-stage cancer patients. However, the tissue absorption of laser light limits the clinical applications of LIT in patients with dark skin, or with deep tumors. The present study is designed to investigate the thermal effects of interstitial irradiation using an 805-nm laser with a cylindrical diffuser, in order to overcome the limitations of the non-invasive mode of treatment. Cow liver and rat tumors were irradiated using interstitial fiber. The temperature increase was monitored by thermocouples that were inserted into the tissue at different sites around the cylinder fiber. Three-dimensional temperature distribution in target tissues during and after interstitial laser irradiation was also determined by Proton Resonance Frequency. The preliminary results showed that the output power of laser and the optical parameters of the target tissue determined the light distribution in the tissue. The temperature distributions varied in the tissue according to the locations relative to the active tip of the cylindrical diffuser. The temperature increase is strongly related to the laser power and irradiation time. Our results using thermocouples and optical sensors indicated that the PRF method is reliable and accurate for temperature determination. Although the inhomogeneous biological tissues could result in temperature fluctuation, the temperature trend still can be reliable enough for the guidance of interstitial irradiation. While this study provides temperature profiles in tumor tissue during interstitial irradiation, the biological effects of the irradiation remain unclear. Future studies will be needed, particularly in combination with the application of immunostimulant for inducing tumor-specific immune responses in the treatment of metastatic tumors.

A preliminary study of factors affecting the calibration stability of the iridium versus iridium-40 percent rhodium thermocouple

NASA Technical Reports Server (NTRS)

Ahmed, Shaffiq; Germain, Edward F.; Daryabeigi, Kamran; Alderfer, David W.; Wright, Robert E.

1987-01-01

An iridium versus iridium-40% rhodium thermocouple was studied. Problems associated with the use of this thermocouple for high temperature applications (up to 2000 C) were investigated. The metallurgical studies included X-ray, macroscopic, resistance, and metallographic studies. The thermocouples in the as-received condition from the manufacturer revealed large amounts of internal stress caused by cold working during manufacturing. The thermocouples also contained a large amount of inhomogeneities and segregations. No phase transformations were observed in the alloy up to 1100 C. It was found that annealing the thermocouple at 1800 C for two hours, and then at 1400 C for 2 to 3 hours yielded a fine grain structure, relieving some of the strains, and making the wire more ductile. It was also found that the above annealing procedure stabilized the thermal emf behavior of the thermocouple for application below 1800 C (an improvement from + or - 1% to + or - 0.02% within the range of the test parameters used).

Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

NASA Technical Reports Server (NTRS)

Morris, J. F. (Inventor)

1977-01-01

Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

Realization of Ru-C Eutectic Point for Evaluation of W-Re and IrRh/Ir Thermocouples

NASA Astrophysics Data System (ADS)

Ogura, H.; Masuyama, S.; Izuchi, M.; Yamazawa, K.; Arai, M.

2015-03-01

Tungsten-rhenium (W-Re) thermocouples are widely used in industry for measurements at high temperatures, up to . Since the electromotive force (emf) of a W-Re thermocouple is known to change during exposure at high temperatures, evaluation of the emf stability is essential for measuring temperature precisely and for realizing precise temperature control used to ensure the quality of products subject to annealing processes. To evaluate precisely the thermoelectric stability around , two Ru-C cells (crucible and Ru-C eutectic alloy) were constructed in our laboratory. The key feature of the cells is that their dimensions are large to ensure there is sufficient immersion available to evaluate the homogeneity characteristics of the thermocouples. By using one of the Ru-C cells, the drift and inhomogeneity of Type C (tungsten-5 % rhenium vs tungsten-26 % rhenium) thermocouples during an exposure to high temperature around were evaluated. Furthermore, to explore possible applications of the eutectic point to other types of high-temperature thermocouples, the drift of an IrRh/Ir thermocouple (iridium-40 % rhodium vs iridium) was also evaluated using another Ru-C cell. The tests with W-Re and IrRh/Ir thermocouples demonstrate that the newly developed Ru-C cells can be used to successfully realize melting plateaux repeatedly. This enables the long-term drift measurements essential for the evaluation and improvement of high-temperature thermocouples. The results obtained in this study will also be useful for evaluating the uncertainty of thermocouple calibrations at around.

Thermal effects associated with the Nd/YAG dental laser.

PubMed

von Fraunhofer, J A; Allen, D J

1993-01-01

The heat produced at the dentinal pulpal wall opposite the irradiation site was measured during etching of dental enamel with an Nd:YAG laser in preparation for direct bonding of orthodontic appliances. Forty extracted human teeth were randomly divided into four groups of 10 teeth. Within each group, the buccal surfaces of 5 teeth and the lingual surfaces of the other 5 teeth were laser treated for 12 sec. Irradiation was performed with a commercial Nd:YAG laser at the power settings of 80mJ, 1W, 2W and 3W. Prior to irradiation, an occlusal access preparation was made into the pulp in order to facilitate the placement of a thermocouple for measurement of temperature changes at the dentinal pulpal wall opposite the irradiation site. The thermocouple was held against the dentinal pulpal wall and the resulting temperature changes were recorded. Heating effects at the dentinal pulpal wall on both buccal and lingual surfaces showed an increase in heat as a function of the increase in power output from the laser unit (p < 0.01). The temperatures measured at power levels 1-3W appeared to be of sufficient magnitude to cause at least localized pulpal inflammation and possible irreversible damage to the pulp tissue immediately opposite the site of laser irradiation.

Assessment of thermal effects of interstitial laser phototherapy on mammary tumors using proton resonance frequency method

PubMed Central

Le, Kelvin; Li, Xiaosong; Figueroa, Daniel; Towner, Rheal A.; Garteiser, Philippe; Saunders, Debra; Smith, Nataliya; Liu, Hong; Hode, Tomas; Nordquist, Robert E.; Chen, Wei R.

2011-01-01

Laser immunotherapy (LIT) uses a synergistic approach to treat cancer systemically through local laser irradiation and immunological stimulation. Currently, LIT utilizes dye-assisted noninvasive laser irradiation to achieve selective photothermal interaction. However, LIT faces difficulties treating deeper tumors or tumors with heavily pigmented overlying skin. To circumvent these barriers, we use interstitial laser irradiation to induce the desired photothermal effects. The purpose of this study is to analyze the thermal effects of interstitial irradiation using proton resonance frequency (PRF). An 805-nm near-infrared laser with an interstitial cylindrical diffuser was used to treat rat mammary tumors. Different power settings (1.0, 1.25, and 1.5 W) were applied with an irradiation duration of 10 min. The temperature distributions of the treated tumors were measured by a 7 T magnetic resonance imager using PRF. We found that temperature distributions in tissue depended on both laser power and time settings, and that variance in tissue composition has a major influence in temperature elevation. The temperature elevations measured during interstitial laser irradiation by PRF and thermocouple were consistent, with some variations due to tissue composition and the positioning of the thermocouple's needle probes. Our results indicated that, for a tissue irradiation of 10 min, the elevation of rat tumor temperature ranged from 8 to 11°C for 1 W and 8 to 15°C for 1.5 W. This is the first time a 7 T magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. Our work provides a basic understanding of the photothermal interaction needed to control the thermal damage inside a tumor using interstitial laser treatment. Our work may lead to an optimal protocol for future cancer treatment using interstitial phototherapy in conjunction with immunotherapy. PMID:22191937

A Self-Validation Method for High-Temperature Thermocouples Under Oxidizing Atmospheres

NASA Astrophysics Data System (ADS)

Mokdad, S.; Failleau, G.; Deuzé, T.; Briaudeau, S.; Kozlova, O.; Sadli, M.

2015-08-01

Thermocouples are prone to significant drift in use particularly when they are exposed to high temperatures. Indeed, high-temperature exposure can affect the response of a thermocouple progressively by changing the structure of the thermoelements and inducing inhomogeneities. Moreover, an oxidizing atmosphere contributes to thermocouple drift by changing the chemical nature of the metallic wires by the effect of oxidation. In general, severe uncontrolled drift of thermocouples results from these combined influences. A periodic recalibration of the thermocouple can be performed, but sometimes it is not possible to remove the sensor out of the process. Self-validation methods for thermocouples provide a solution to avoid this drawback, but there are currently no high-temperature contact thermometers with self-validation capability at temperatures up to . LNE-Cnam has developed fixed-point devices integrated to the thermocouples consisting of machined alumina-based devices for operation under oxidizing atmospheres. These devices require small amounts of pure metals (typically less than 2 g). They are suitable for self-validation of high-temperature thermocouples up to . In this paper the construction and the characterization of these integrated fixed-point devices are described. The phase-transition plateaus of gold, nickel, and palladium, which enable coverage of the temperature range between and , are assessed with this self-validation technique. Results of measurements performed at LNE-Cnam with the integrated self-validation module at several levels of temperature will be presented. The performance of the devices are assessed and discussed, in terms of robustness and metrological characteristics. Uncertainty budgets are also proposed and detailed.

Laser-enhanced high-intensity focused ultrasound heating in an in vivo small animal model

NASA Astrophysics Data System (ADS)

Jo, Janggun; Yang, Xinmai

2016-11-01

The enhanced heating effect during the combination of high-intensity focused ultrasound (HIFU) and low-optical-fluence laser illumination was investigated by using an in vivo murine animal model. The thighs of murine animals were synergistically irradiated by HIFU and pulsed nano-second laser light. The temperature increases in the target region were measured by a thermocouple under different HIFU pressures, which were 6.2, 7.9, and 9.8 MPa, in combination with 20 mJ/cm2 laser exposures at 532 nm wavelength. In comparison with conventional laser therapies, the laser fluence used here is at least one order of magnitude lower. The results showed that laser illumination could enhance temperature during HIFU applications. Additionally, cavitation activity was enhanced when laser and HIFU irradiation were concurrently used. Further, a theoretical simulation showed that the inertial cavitation threshold was indeed decreased when laser and HIFU irradiation were utilized concurrently.

AGR-2 and AGR-3/4 Release-to-Birth Ratio Data Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, Binh T.; Einerson, Jeffrey J.; Scates, Dawn M.

A series of Advanced Gas Reactor (AGR) irradiation tests is being conducted in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) in support of development and qualification of tristructural isotropic (TRISO) low enriched fuel used in the High Temperature Gas-cooled Reactor (HTGR). Each AGR test consists of multiple independently controlled and monitored capsules containing fuel compacts placed in a graphite cylinder shrouded by a steel shell. These capsules are instrumented with thermocouples embedded in the graphite enabling temperature control. AGR configuration and irradiation conditions are based on prismatic HTGR technology that is distinguished primarily through use of heliummore » coolant, a low-power-density ceramic core capable of withstanding very high temperatures, and TRISO coated particle fuel. Thus, these tests provide valuable irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, and support development and validation of fuel performance and fission product transport models and codes.« less

An intelligent instrument for measuring exhaust temperature of marine engine

NASA Astrophysics Data System (ADS)

Ma, Nan-Qi; Su, Hua; Liu, Jun

2006-12-01

Exhaust temperature of the marine engine is commonly measured through thermocouple. Measure deviation will occur after using the thermocouple for some time due to nonlinearity of thermocouple itself, high temperature and chemical corrosion of measure point. Frequent replacement of thermocouple will increase the operating cost. This paper designs a new intelligent instrument for solving the above-mentioned problems of the marine engine temperature measurement, which combines the conventional thermocouple temperature measurement technology and SCM(single chip microcomputer). The reading of the thermocouple is simple and precise and the calibration can be made automatically and manually.

Computer program for pulsed thermocouples with corrections for radiation effects

NASA Technical Reports Server (NTRS)

Will, H. A.

1981-01-01

A pulsed thermocouple was used for measuring gas temperatures above the melting point of common thermocouples. This was done by allowing the thermocouple to heat until it approaches its melting point and then turning on the protective cooling gas. This method required a computer to extrapolate the thermocouple data to the higher gas temperatures. A method that includes the effect of radiation in the extrapolation is described. Computations of gas temperature are provided, along with the estimate of the final thermocouple wire temperature. Results from tests on high temperature combustor research rigs are presented.

A miniature high-temperature fixed point for self-validation of type C thermocouples

NASA Astrophysics Data System (ADS)

Ongrai, O.; Pearce, J. V.; Machin, G.; Sweeney, S. J.

2011-10-01

Reliable high-temperature (>1500 °C) measurement is crucial for a wide range of industrial processes as well as specialized applications, e.g. aerospace. The most common type of sensor used for high-temperature measurement is the thermocouple. At and above 1500 °C, tungsten-rhenium (W-Re) thermocouples are the most commonly used temperature sensors due to their utility up to 2300 °C. However, the achievable accuracy of W-Re thermocouples is seriously limited by the effects of their inhomogeneity, drift and hysteresis. Furthermore, due to their embrittlement at high temperature, the removal of these thermocouples from environments such as nuclear power plants or materials processing furnaces for recalibration is generally not possible. Even if removal for recalibration were possible, this would be of, at best, very limited use due to large inhomogeneity effects. Ideally, these thermocouples require some mechanism to monitor their drift in situ. In this study, we describe a miniature Co-C eutectic fixed-point cell to evaluate the stability of type C (W5%Re/W26%Re) thermocouples by means of in situ calibration.

A setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials

NASA Astrophysics Data System (ADS)

Fu, Qiang; Xiong, Yucheng; Zhang, Wenhua; Xu, Dongyan

2017-09-01

This paper presents a setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials. The sample holder was designed to have a compact structure and can be directly mounted in a standard cryostat system for temperature-dependent measurements. For the Seebeck coefficient measurement, a thin bar-shaped sample is mounted bridging two copper bases; and two ceramic heaters are used to generate a temperature gradient along the sample. Two type T thermocouples are used to determine both temperature and voltage differences between two widely separated points on the sample. The thermocouple junction is flattened into a disk and pressed onto the sample surface by using a spring load. The flexible fixation method we adopted not only simplifies the sample mounting process but also prevents thermal contact deterioration due to the mismatch of thermal expansion coefficients between the sample and other parts. With certain modifications, the sample holder can also be used for four-probe electrical resistivity measurements. High temperature measurements are essential for thermoelectric power generation. The experimental system we developed is capable of measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials in a wide temperature range from 80 to 500 K, which can be further extended to even higher temperatures. Measurements on two standard materials, constantan and nickel, confirmed the accuracy and the reliability of the system.

Attachment of lead wires to thin film thermocouples mounted on high temperature materials using the parallel gap welding process

NASA Technical Reports Server (NTRS)

Holanda, Raymond; Kim, Walter S.; Pencil, Eric; Groth, Mary; Danzey, Gerald A.

1990-01-01

Parallel gap resistance welding was used to attach lead wires to sputtered thin film sensors. Ranges of optimum welding parameters to produce an acceptable weld were determined. The thin film sensors were Pt13Rh/Pt thermocouples; they were mounted on substrates of MCrAlY-coated superalloys, aluminum oxide, silicon carbide and silicon nitride. The entire sensor system is designed to be used on aircraft engine parts. These sensor systems, including the thin-film-to-lead-wire connectors, were tested to 1000 C.

Refractory oxide insulated thermocouple designed and analyzed for high temperature applications

NASA Technical Reports Server (NTRS)

Popper, G. F.; Zeren, T. Z.

1969-01-01

Study establishes design criteria for constructing high temperature thermocouple to measure nuclear fuel pin temperature. The study included a literature search to determine the compatibility of material useful for thermocouples, a hot zone error analysis, and a prototype design for hot junction and connector pin connections.

Error sources affecting thermocouple thermometry in RF electromagnetic fields.

PubMed

Chakraborty, D P; Brezovich, I A

1982-03-01

Thermocouple thermometry errors in radiofrequency (typically 13, 56 MHZ) electromagnetic fields such as are encountered in hyperthermia are described. RF currents capacitatively or inductively coupled into the thermocouple-detector circuit produce errors which are a combination of interference, i.e., 'pick-up' error, and genuine rf induced temperature changes at the junction of the thermocouple. The former can be eliminated by adequate filtering and shielding; the latter is due to (a) junction current heating in which the generally unequal resistances of the thermocouple wires cause a net current flow from the higher to the lower resistance wire across the junction, (b) heating in the surrounding resistive material (tissue in hyperthermia), and (c) eddy current heating of the thermocouple wires in the oscillating magnetic field. Low frequency theories are used to estimate these errors under given operating conditions and relevant experiments demonstrating these effects and precautions necessary to minimize the errors are described. It is shown that at 13.56 MHz and voltage levels below 100 V rms these errors do not exceed 0.1 degrees C if the precautions are observed and thermocouples with adequate insulation (e.g., Bailey IT-18) are used. Results of this study are being currently used in our clinical work with good success.

Temperature measurements during high flux ion beam irradiations

DOE PAGES

Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; ...

2016-02-16

A systematic study of the ion beam heating effect was performed in a temperature range of –170 to 900 °C using a 10 MeV Au 3+ ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 10 12 cm –2 s –1. Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing temperature. Comparisonmore » with numerical calculations suggests that the observed heating effect is, in reality, a predominantly electronic effect and the true temperature rise is small. Furthermore, a simple model was developed to explain this electronic effect in terms of an electrostatic potential that forms during ion irradiation. Such an artificial beam heating effect is potentially problematic in thermostated ion irradiation and ion beamanalysis apparatus, as the operation of temperature feedback systems can be significantly distorted by this effect.« less

Thin-Film Ceramic Thermocouples Fabricated and Tested

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Farmer, Serene C.; Sayir, Ali; Gregory, Otto J.; Blaha, Charles A.

2004-01-01

The Sensors and Electronics Technology Branch of the NASA Glenn Research Center is developing thin-film-based sensors for surface measurement in propulsion system research. Thin-film sensors do not require special machining of the components on which they are mounted, and they are considerably thinner than wire- or foil-based sensors. One type of sensor being advanced is the thin-film thermocouple, specifically for applications in high-temperature combustion environments. Ceramics are being demonstrated as having the potential to meet the demands of thin-film thermocouples in advanced aerospace environments. The maximum-use temperature of noble metal thin-film thermocouples, 1500 C (2700 F), may not be adequate for components used in the increasingly harsh conditions of advanced aircraft and next-generation launch vehicles. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically in the form of bulky rods or probes. As part of ASTP, Glenn's Sensors and Electronics Technology Branch is leading an in-house effort to apply ceramics as thin-film thermocouples for extremely high-temperature applications as part of ASTP. Since the purity of the ceramics is crucial for the stability of the thermocouples, Glenn's Ceramics Branch and Case Western Reserve University are developing high-purity ceramic sputtering targets for fabricating high-temperature sensors. Glenn's Microsystems Fabrication Laboratory, supported by the Akima Corporation, is using these targets to fabricate thermocouple samples for testing. The first of the materials used were chromium silicide (CrSi) and tantalum carbide (TaC). These refractory materials are expected to survive temperatures in excess of 1500 C. Preliminary results indicate that the thermoelectric voltage output of a thin-film CrSi versus TaC thermocouple is 15 times that of the standard type R (platinum-rhodium versus platinum) thermocouple, producing 20 mV with a 200 C temperature gradient. The photograph on the left shows the CrSi-TaC thermocouple in a test fixture at Glenn, and the resulting output signal is shown on the right. The temperature differential across the sample, from the center of the sample inside the oven to the sample mount outside the oven, is measured using a type R thermocouple on the sample.

In vitro pulp chamber temperature rise from irradiation and exotherm of flowable composites.

PubMed

Baroudi, Kusai; Silikas, Nick; Watts, David C

2009-01-01

The aim of this study was to investigate the pulpal temperature rise induced during the polymerization of flowable and non-flowable composites using light-emitting diode (LED) and halogen (quartz-tungsten-halogen) light-curing units (LCUs). Five flowable and three non-flowable composites were examined. Pulpal temperature changes were recorded over 10 min in a sample primary tooth by a thermocouple. A conventional quartz-tungsten-halogen source and two LEDs, one of which was programmable, were used for light curing the resin composites. Three repetitions per material were made for each LCU. There was a wide range of temperature rises among the materials (P < 0.05). Temperature rises ranged between 1.3 degrees C for Filtek Supreme irradiated by low-power LED and 4.5 degrees C for Grandio Flow irradiated by high-power LED. The highest temperature rises were observed with both the LED high-power and soft-start LCUs. The time to reach the exothermic peak varied significantly between the materials (P < 0.05). Pulpal temperature rise is related to both the radiant energy output from LCUs and the polymerization exotherm of resin composites. A greater potential risk for heat-induced pulp damage might be associated with high-power LED sources. Flowable composites exhibited higher temperature rises than non-flowable materials, because of higher resin contents.

HIGH TEMPERATURE THERMOCOUPLE

DOEpatents

Eshayu, A.M.

1963-02-12

This invention contemplates a high temperature thermocouple for use in an inert or a reducing atmosphere. The thermocouple limbs are made of rhenium and graphite and these limbs are connected at their hot ends in compressed removable contact. The rhenium and graphite are of high purity and are substantially stable and free from diffusion into each other even without shielding. Also, the graphite may be thick enough to support the thermocouple in a gas stream. (AEC)

An in vitro investigation of the temperature rises produced in dentine by Nd:YAG laser light with and without water cooling.

PubMed

Gow, A M; McDonald, A V; Pearson, G J; Setchell, D J

1999-01-01

Infrared lasers are reported to have thermal side effects which may damage pulp tissue. This study investigated the thermal effects of the pulsed Nd:YAG laser. Prepared, extracted teeth were measured prior to irradiation. Temperature was recorded using a thermocouple/data logging system. Laser irradiation was carried out with or without water spray for an exposure time of ten seconds. Results indicated that dry irradiation produced unacceptable temperature rises with dentine thicknesses used. Wet irradiation produced a significantly lower temperature rise. It was concluded that the Nd:YAG laser produced thermal effects which could potentially cause pulpal trauma. A water coolant was effective in reducing these thermal effects, but the temperature rise achieved whilst using water coolant may still cause pulpal damage.

High-temperature, long-term drift of platinum-rhodium thermocouples

NASA Technical Reports Server (NTRS)

Szaniszlo, A. J.

1970-01-01

Contamination of thermocouples is minimized by use of pure alumina insulators and a controlled low-impurity-level high-vacuum environment. Average thermal electromotive force change for platinum-rhodium thermocouples was -2.8 deg K after 3700 hours exposure to a mean temperature of 1530 deg K.

Thermoelectric Mixed Thick-/Thin Film Microgenerators Based on Constantan/Silver.

PubMed

Gierczak, Mirosław; Prażmowska-Czajka, Joanna; Dziedzic, Andrzej

2018-01-12

This paper describes the design, manufacturing and characterization of newly developed mixed thick-/thin film thermoelectric microgenerators based on magnetron sputtered constantan (copper-nickel alloy) and screen-printed silver layers. The thermoelectric microgenerator consists of sixteen thermocouples made on a 34.2 × 27.5 × 0.25 mm³ alumina substrate. One of thermocouple arms was made of magnetron-sputtered constantan (Cu-Ni alloy), the second was a Ag-based screen-printed film. The length of each thermocouple arm was equal to 27 mm, and their width 0.3 mm. The distance between the arms was equal to 0.3 mm. In the first step, a pattern mask with thermocouples was designed and fabricated. Then, a constantan layer was magnetron sputtered over the whole substrate, and a photolithography process was used to prepare the first thermocouple arms. The second arms were screen-printed onto the substrate using a low-temperature silver paste (Heraeus C8829A or ElectroScience Laboratories ESL 599-E). To avoid oxidation of constantan, they were fired in a belt furnace in a nitrogen atmosphere at 550/450 °C peak firing temperature. Thermoelectric and electrical measurements were performed using the self-made measuring system. Two pyrometers included into the system were used for temperature measurement of hot and cold junctions. The estimated Seebeck coefficient, α was from the range 35 - 41 µV/K, whereas the total internal resistances R were between 250 and 3200 ohms, depending on magnetron sputtering time and kind of silver ink (the resistance of a single thermocouple was between 15.5 and 200 ohms).

Thermoelectric Mixed Thick-/Thin Film Microgenerators Based on Constantan/Silver

PubMed Central

Gierczak, Mirosław; Prażmowska-Czajka, Joanna; Dziedzic, Andrzej

2018-01-01

This paper describes the design, manufacturing and characterization of newly developed mixed thick-/thin film thermoelectric microgenerators based on magnetron sputtered constantan (copper-nickel alloy) and screen-printed silver layers. The thermoelectric microgenerator consists of sixteen thermocouples made on a 34.2 × 27.5 × 0.25 mm3 alumina substrate. One of thermocouple arms was made of magnetron-sputtered constantan (Cu-Ni alloy), the second was a Ag-based screen-printed film. The length of each thermocouple arm was equal to 27 mm, and their width 0.3 mm. The distance between the arms was equal to 0.3 mm. In the first step, a pattern mask with thermocouples was designed and fabricated. Then, a constantan layer was magnetron sputtered over the whole substrate, and a photolithography process was used to prepare the first thermocouple arms. The second arms were screen-printed onto the substrate using a low-temperature silver paste (Heraeus C8829A or ElectroScience Laboratories ESL 599-E). To avoid oxidation of constantan, they were fired in a belt furnace in a nitrogen atmosphere at 550/450 °C peak firing temperature. Thermoelectric and electrical measurements were performed using the self-made measuring system. Two pyrometers included into the system were used for temperature measurement of hot and cold junctions. The estimated Seebeck coefficient, α was from the range 35 − 41 µV/K, whereas the total internal resistances R were between 250 and 3200 ohms, depending on magnetron sputtering time and kind of silver ink (the resistance of a single thermocouple was between 15.5 and 200 ohms). PMID:29329203

Welding Wires To Thin Thermocouple Films

NASA Technical Reports Server (NTRS)

Holanda, Raymond; Kim, Walter S.; Danzey, Gerald A.; Pencil, Eric; Wadel, Mary

1993-01-01

Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

Simulating the Gradually Deteriorating Performance of an RTG

NASA Technical Reports Server (NTRS)

Wood, Eric G.; Ewell, Richard C.; Patel, Jagdish; Hanks, David R.; Lozano, Juan A.; Snyder, G. Jeffrey; Noon, Larry

2008-01-01

Degra (now in version 3) is a computer program that simulates the performance of a radioisotope thermoelectric generator (RTG) over its lifetime. Degra is provided with a graphical user interface that is used to edit input parameters that describe the initial state of the RTG and the time-varying loads and environment to which it will be exposed. Performance is computed by modeling the flows of heat from the radioactive source and through the thermocouples, also allowing for losses, to determine the temperature drop across the thermocouples. This temperature drop is used to determine the open-circuit voltage, electrical resistance, and thermal conductance of the thermocouples. Output power can then be computed by relating the open-circuit voltage and the electrical resistance of the thermocouples to a specified time-varying load voltage. Degra accounts for the gradual deterioration of performance attributable primarily to decay of the radioactive source and secondarily to gradual deterioration of the thermoelectric material. To provide guidance to an RTG designer, given a minimum of input, Degra computes the dimensions, masses, and thermal conductances of important internal structures as well as the overall external dimensions and total mass.

Thin film thermocouples for high temperature measurement on ceramic materials

NASA Technical Reports Server (NTRS)

Holanda, Raymond

1992-01-01

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high-heating-rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

Development of Thin Film Ceramic Thermocouples for High Temperature Environments

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Farmer, Serene C.; Sayir, Ali; Blaha, Charles A.; Gonzalez, Jose M.

2004-01-01

The maximum use temperature of noble metal thin film thermocouples of 1100 C (2000 F) may not be adequate for use on components in the increasingly harsh conditions of advanced aircraft and next generation launch technology. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically found in the form of rods or probes. NASA Glenn Research Center is investigating the feasibility of ceramics as thin film thermocouples for extremely high temperature applications to take advantage of the stability and robustness of ceramics and the non-intrusiveness of thin films. This paper will discuss the current state of development in this effort.

NEUTRONIC REACTOR CORE INSTRUMENT

DOEpatents

Mims, L.S.

1961-08-22

A multi-purpose instrument for measuring neutron flux, coolant flow rate, and coolant temperature in a nuclear reactor is described. The device consists essentially of a hollow thimble containing a heat conducting element protruding from the inner wall, the element containing on its innermost end an amount of fissionsble materinl to function as a heat source when subjected to neutron flux irradiation. Thermocouple type temperature sensing means are placed on the heat conducting element adjacent the fissionable material and at a point spaced therefrom, and at a point on the thimble which is in contact with the coolant fluid. The temperature differentials measured between the thermocouples are determinative of the neutron flux, coolant flow, and temperature being measured. The device may be utilized as a probe or may be incorporated in a reactor core. (AE C)

Contact Thermocouple Methodology and Evaluation for Temperature Measurement in the Laboratory

NASA Technical Reports Server (NTRS)

Brewer, Ethan J.; Pawlik, Ralph J.; Krause, David L.

2013-01-01

Laboratory testing of advanced aerospace components very often requires highly accurate temperature measurement and control devices, as well as methods to precisely analyze and predict the performance of such components. Analysis of test articles depends on accurate measurements of temperature across the specimen. Where possible, this task is accomplished using many thermocouples welded directly to the test specimen, which can produce results with great precision. However, it is known that thermocouple spot welds can initiate deleterious cracks in some materials, prohibiting the use of welded thermocouples. Such is the case for the nickel-based superalloy MarM-247, which is used in the high temperature, high pressure heater heads for the Advanced Stirling Converter component of the Advanced Stirling Radioisotope Generator space power system. To overcome this limitation, a method was developed that uses small diameter contact thermocouples to measure the temperature of heater head test articles with the same level of accuracy as welded thermocouples. This paper includes a brief introduction and a background describing the circumstances that compelled the development of the contact thermocouple measurement method. Next, the paper describes studies performed on contact thermocouple readings to determine the accuracy of results. It continues on to describe in detail the developed measurement method and the evaluation of results produced. A further study that evaluates the performance of different measurement output devices is also described. Finally, a brief conclusion and summary of results is provided.

Base metal thermocouples drift rate dependence from thermoelement diameter

NASA Astrophysics Data System (ADS)

Pavlasek, P.; Duris, S.; Palencar, R.

2015-02-01

Temperature measurements are one of the key factors in many industrial applications that directly affect the quality, effectiveness and safety of manufacturing processes. In many industrial applications these temperature measurements are realized by thermocouples. Accuracy of thermocouples directly affects the quality of the final product of manufacturing and their durability determines the safety margins required. One of the significant effects that affect the precision of the thermocouples is short and long term stability of their voltage output. This stability issue occurs in every type of thermocouples and is caused by multiple factors. In general these factors affect the Seebeck coefficient which is a material constant, which determines the level of generated voltage when exposed to a temperature gradient. Changes of this constant result in the change of the thermocouples voltage output thus indicated temperature which can result in production quality issues, safety and health hazards. These alternations can be caused by physical and chemical changes within the thermocouple lead material. Modification of this material constant can be of temporary nature or permanent. This paper concentrates on the permanent, or irreversible changes of the Seebeck coefficient that occur in commonly used swaged MIMS Type N thermocouples. These permanent changes can be seen as systematic change of the EMF of the thermocouple when it is exposed to a high temperature over a period of time. This change of EMF by time is commonly known as the drift of the thermocouple. This work deals with the time instability of thermocouples EMF at temperatures above 1200 °C. Instability of the output voltage was taken into relation with the lead diameter of the tested thermocouples. This paper concentrates in detail on the change of voltage output of thermocouples of different diameters which were tested at high temperatures for the overall period of more than 210 hours. The gather data from this testing was used to establish the relation between the level of EMF drift and the lead diameter of the thermocouple thermoelements. Furthermore this data was also used to create a drift function which mathematically expresses the dependency between the drift rate and the diameter of the thermocouple leads.

Validation diagnostics for defective thermocouple circuits

NASA Astrophysics Data System (ADS)

Reed, R. P.

Thermocouples, properly used under favorable conditions, can measure temperature with an accepted tolerance. However, when improperly applied or exposed to hostile mechanical, chemical, thermal, or radiation environments, they often fail without the error being evident in the temperature record. Conversely, features that appear to be unreasonable in temperature records can be authentic. When hidden failure occurs during measurement, deliberate recording of supplementary information is necessary to distinguish valid from faulty data. Loop resistance change, circuit isolation, isolated noise potential, and other measures can reveal symptoms of developing defects. Monitored continually along with temperature, they can reveal the occurrence, location, and natures of damage incurred during measurement. Special multiterminal branched thermocouple circuits and combinatorial multiplex switching allow detection of dc measurement noise and decalibration. Symptoms of insidious failure, often consequential, are illustrated by examples from field experience in measuring temperature of a propagating retorting front in underground coal gasification.

Problems encountered in fluctuating flame temperature measurements by thermocouple.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donaldson, A. Burl; Lucero, Ralph E.; Gill, Walter

2008-11-01

Some thermocouple experiments were carried out in order to obtain sensitivity of thermocouple readings to fluctuations in flames and to determine if the average thermocouple reading was representative of the local volume temperature for fluctuating flames. The thermocouples considered were an exposed junction thermocouple and a fully sheathed thermocouple with comparable time constants. Either the voltage signal or indicated temperature for each test was recorded at sampling rates between 300-4,096 Hz. The trace was then plotted with respect to time or sample number so that time variation in voltage or temperature could be visualized and the average indicated temperature couldmore » be determined. For experiments where high sampling rates were used, the signal was analyzed using Fast Fourier Transforms (FFT) to determine the frequencies present in the thermocouple signal. This provided a basic observable as to whether or not the probe was able to follow flame oscillations. To enhance oscillations, for some experiments, the flame was forced. An analysis based on thermocouple time constant, coupled with the transfer function for a sinusoidal input was tested against the experimental results.« less

Problems Encountered in Fluctuating Flame Temperature Measurements by Thermocouple

PubMed Central

Yilmaz, Nadir; Gill, Walt; Donaldson, A. Burl; Lucero, Ralph E.

2008-01-01

Some thermocouple experiments were carried out in order to obtain sensitivity of thermocouple readings to fluctuations in flames and to determine if the average thermocouple reading was representative of the local volume temperature for fluctuating flames. The thermocouples considered were an exposed junction thermocouple and a fully sheathed thermocouple with comparable time constants. Either the voltage signal or indicated temperature for each test was recorded at sampling rates between 300-4,096 Hz. The trace was then plotted with respect to time or sample number so that time variation in voltage or temperature could be visualized and the average indicated temperature could be determined. For experiments where high sampling rates were used, the signal was analyzed using Fast Fourier Transforms (FFT) to determine the frequencies present in the thermocouple signal. This provided a basic observable as to whether or not the probe was able to follow flame oscillations. To enhance oscillations, for some experiments, the flame was forced. An analysis based on thermocouple time constant, coupled with the transfer function for a sinusoidal input was tested against the experimental results. PMID:27873964

Problems Encountered in Fluctuating Flame Temperature Measurements by Thermocouple.

PubMed

Yilmaz, Nadir; Gill, Walt; Donaldson, A Burl; Lucero, Ralph E

2008-12-04

Some thermocouple experiments were carried out in order to obtain sensitivity of thermocouple readings to fluctuations in flames and to determine if the average thermocouple reading was representative of the local volume temperature for fluctuating flames. The thermocouples considered were an exposed junction thermocouple and a fully sheathed thermocouple with comparable time constants. Either the voltage signal or indicated temperature for each test was recorded at sampling rates between 300-4,096 Hz. The trace was then plotted with respect to time or sample number so that time variation in voltage or temperature could be visualized and the average indicated temperature could be determined. For experiments where high sampling rates were used, the signal was analyzed using Fast Fourier Transforms (FFT) to determine the frequencies present in the thermocouple signal. This provided a basic observable as to whether or not the probe was able to follow flame oscillations. To enhance oscillations, for some experiments, the flame was forced. An analysis based on thermocouple time constant, coupled with the transfer function for a sinusoidal input was tested against the experimental results.

Fe, Co, Ni: Electrical Resistivity Along their Melting Boundaries

NASA Astrophysics Data System (ADS)

Silber, R. E.; Ezenwa, I.; Secco, R.; Yong, W.

2017-12-01

Electrical resistivity of Fe, Co, and Ni was measured at pressures up to 11 GPa and temperatures into their liquid states in multi-anvil and cubic-anvil presses. Two thermocouples placed at opposite ends of the wire sample served as T probes as well as 4-wire resistance electrodes in a switched circuit. A polarity switch was also used to remove any bias associated with current flow and voltage measurement using thermocouple legs. Post experimental examination of recovered and sectioned samples was done using electron microprobe analyses to check for diffusion in our samples. The observed large jumps in resistivity at the high P melting T of each metal is consistent with its known P,T phase diagram and with post-run compositional analyses. The electrical resistivity behavior in these late transition metals as a function of increasing P and T shows expected trends consistent with 1atm data. Within the error of measurement, the resistivity values at the melting T at high P of Co and Ni appear to mimic their 1 atm value suggesting constant resistivity along the melting boundary. For liquid Fe, resistivity decreases along the melting boundary up to the triple point at 5.2 GPa, and then is nearly constant at higher pressures. The results are compared to prediction by Stacey and Loper (PEPI, 2007).

Applications of Thin Film Thermocouples for Surface Temperature Measurement

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Holanda, Raymond

1994-01-01

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

Use of a soft sensor for the fast estimation of dried cake resistance during a freeze-drying cycle.

PubMed

Bosca, Serena; Barresi, Antonello A; Fissore, Davide

2013-07-15

This paper deals with the determination of dried cake resistance in a freeze-drying process using the Smart Soft Sensor, a process analytical technology recently proposed by the authors to monitor the primary drying stage of a freeze-drying process. This sensor uses the measurement of product temperature, a mathematical model of the process, and the Kalman filter algorithm to estimate the residual amount of ice in the vial as a function of time, as well as the coefficient of heat transfer between the shelf and the product and the resistance of the dried cake to vapor flow. It does not require expensive (additional) hardware in a freeze-dryer, provided that thermocouples are available. At first, the effect of the insertion of the thermocouple in a vial on the structure of the product is investigated by means of experimental tests, comparing both sublimation rate and cake structure in vials with and without thermocouple. This is required to assess that the temperature measured by the thermocouple is the same of the product in the non-monitored vials, at least in a non-GMP environment, or when controlled nucleation methods are used. Then, results about cake resistance obtained in an extended experimental campaign with aqueous solutions containing different excipients (sucrose, mannitol and polyvinylpyrrolidone), processed in various operating conditions, are presented, with the goal to point out the accuracy of the proposed methodology. Copyright © 2013 Elsevier B.V. All rights reserved.

Blind system identification of two-thermocouple sensor based on cross-relation method.

PubMed

Li, Yanfeng; Zhang, Zhijie; Hao, Xiaojian

2018-03-01

In dynamic temperature measurement, the dynamic characteristics of the sensor affect the accuracy of the measurement results. Thermocouples are widely used for temperature measurement in harsh conditions due to their low cost, robustness, and reliability, but because of the presence of the thermal inertia, there is a dynamic error in the dynamic temperature measurement. In order to eliminate the dynamic error, two-thermocouple sensor was used to measure dynamic gas temperature in constant velocity flow environments in this paper. Blind system identification of two-thermocouple sensor based on a cross-relation method was carried out. Particle swarm optimization algorithm was used to estimate time constants of two thermocouples and compared with the grid based search method. The method was validated on the experimental equipment built by using high temperature furnace, and the input dynamic temperature was reconstructed by using the output data of the thermocouple with small time constant.

Blind system identification of two-thermocouple sensor based on cross-relation method

NASA Astrophysics Data System (ADS)

Li, Yanfeng; Zhang, Zhijie; Hao, Xiaojian

2018-03-01

In dynamic temperature measurement, the dynamic characteristics of the sensor affect the accuracy of the measurement results. Thermocouples are widely used for temperature measurement in harsh conditions due to their low cost, robustness, and reliability, but because of the presence of the thermal inertia, there is a dynamic error in the dynamic temperature measurement. In order to eliminate the dynamic error, two-thermocouple sensor was used to measure dynamic gas temperature in constant velocity flow environments in this paper. Blind system identification of two-thermocouple sensor based on a cross-relation method was carried out. Particle swarm optimization algorithm was used to estimate time constants of two thermocouples and compared with the grid based search method. The method was validated on the experimental equipment built by using high temperature furnace, and the input dynamic temperature was reconstructed by using the output data of the thermocouple with small time constant.

Seebeck Coefficient of Thermocouples from Nickel-Coated Carbon Fibers: Theory and Experiment.

PubMed

Hardianto, Hardianto; De Mey, Gilbert; Ciesielska-Wrόbel, Izabela; Hertleer, Carla; Van Langenhove, Lieva

2018-05-30

Thermocouples made of etched and non-etched nickel-coated carbon yarn (NiCCY) were investigated. Theoretic Seebeck coefficients were compared to experimental results from measurements of generated electric voltage by these thermocouples. The etching process for making thermocouples was performed by immersion of NiCCY in the solution containing a mixture of hydrochloric acid (HCl) (37% of concentration), and hydrogen peroxide (H₂O₂) in three different concentrations-3%, 6%, and 10%. Thirty minutes of etching to remove Ni from NiCCY was followed by washing and drying. Next, the ability to generate electrical voltage by the thermocouples (being a junction of the etched and the non-etched NiCCY) was measured in different ranges of temperatures, both a cold junction (291.15⁻293.15 K) and a hot junction (293.15⁻325.15 K). A formula predicting the Seebeck coefficient of this thermocouple was elaborated, taking into consideration resistance values of the tested samples. It was proven that there is a good agreement between the theoretical and experimental data, especially for the yarns etched with 6% and 10% peroxide (both were mixed with HCl). The electrical resistance of non-fully etched nickel remaining on the carbon fiber surface ( R 1 ) can have a significant effect on the thermocouples' characteristics.

Instrument for stable high temperature Seebeck coefficient and resistivity measurements under controlled oxygen partial pressure

DOE PAGES

Ihlefeld, Jon F.; Brown-Shaklee, Harlan James; Sharma, Peter Anand

2015-04-28

The transport properties of ceramic materials strongly depend on oxygen activity, which is tuned by changing the partial oxygen pressure (pO 2) prior to and during measurement. Within, we describe an instrument for highly stable measurements of Seebeck coefficient and electrical resistivity at temperatures up to 1300 K with controlled oxygen partial pressure. An all platinum construction is used to avoid potential materials instabilities that can cause measurement drift. Two independent heaters are employed to establish a small temperature gradient for Seebeck measurements, while keeping the average temperature constant and avoiding errors associated with pO 2-induced drifts in thermocouple readings.more » Oxygen equilibrium is monitored using both an O 2 sensor and the transient behavior of the resistance as a proxy. A pO 2 range of 10 -25–10 0 atm can be established with appropriate gas mixtures. Seebeck measurements were calibrated against a high purity platinum wire, Pt/Pt–Rh thermocouple wire, and a Bi 2Te3 Seebeck coefficient Standard Reference Material. To demonstrate the utility of this instrument for oxide materials we present measurements as a function of pO 2 on a 1 % Nb-doped SrTiO 3 single crystal, and show systematic changes in properties consistent with oxygen vacancy defect chemistry. Thus, an approximately 11% increase in power factor over a pO 2 range of 10 -19–10 -8 atm at 973 K for the donor-doped single crystals is observed.« less

Lower operational costs in heat treatment and process engineering through improved temperature measurement

NASA Astrophysics Data System (ADS)

Furniss, C. P.

New metal-sheathed thermocouple systems are described which have lowered operational heat treatment costs and process engineering. The improvements which these thermocouples represent over conventional ones with regard to chemical composition, thermomechanical properties, oxidation resistance, weldability, and coefficient of linear expansion are pointed out. Experimentally determined cost savings for a variety of applications are reported.

Metallic and Ceramic Thin Film Thermocouples for Gas Turbine Engines

PubMed Central

Tougas, Ian M.; Amani, Matin; Gregory, Otto J.

2013-01-01

Temperatures of hot section components in today's gas turbine engines reach as high as 1,500 °C, making in situ monitoring of the severe temperature gradients within the engine rather difficult. Therefore, there is a need to develop instrumentation (i.e., thermocouples and strain gauges) for these turbine engines that can survive these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have excellent chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings commonly employed in today's engines, they have greater sensitivity than conventional wire thermocouples, and they are non-invasive to combustion aerodynamics in the engine. Thin film thermocouples based on platinum:palladium and indium oxynitride:indium tin oxynitride as well as their oxide counterparts have been developed for this purpose and have proven to be more stable than conventional type-S and type-K thin film thermocouples. The metallic and ceramic thin film thermocouples described within this paper exhibited remarkable stability and drift rates similar to bulk (wire) thermocouples. PMID:24217356

Metallic and ceramic thin film thermocouples for gas turbine engines.

PubMed

Tougas, Ian M; Amani, Matin; Gregory, Otto J

2013-11-08

Temperatures of hot section components in today's gas turbine engines reach as high as 1,500 °C, making in situ monitoring of the severe temperature gradients within the engine rather difficult. Therefore, there is a need to develop instrumentation (i.e., thermocouples and strain gauges) for these turbine engines that can survive these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have excellent chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings commonly employed in today's engines, they have greater sensitivity than conventional wire thermocouples, and they are non-invasive to combustion aerodynamics in the engine. Thin film thermocouples based on platinum:palladium and indium oxynitride:indium tin oxynitride as well as their oxide counterparts have been developed for this purpose and have proven to be more stable than conventional type-S and type-K thin film thermocouples. The metallic and ceramic thin film thermocouples described within this paper exhibited remarkable stability and drift rates similar to bulk (wire) thermocouples.

Ecophysiological function of leaf 'windows' in Lithops species - 'Living Stones' that grow underground.

PubMed

Martin, C E; Brandmeyer, E A; Ross, R D

2013-01-01

Leaf temperatures were lower when light entry at the leaf tip window was prevented through covering the window with reflective tape, relative to leaf temperatures of plants with leaf tip windows covered with transparent tape. This was true when leaf temperatures were measured with an infrared thermometer, but not with a fine-wire thermocouple. Leaf tip windows of Lithops growing in high-rainfall regions of southern Africa were larger than the windows of plants (numerous individuals of 17 species) growing in areas with less rainfall and, thus, more annual insolation. The results of this study indicate that leaf tip windows of desert plants with an underground growth habit can allow entry of supra-optimal levels of radiant energy, thus most likely inhibiting photosynthetic activity. Consequently, the size of the leaf tip windows correlates inversely with habitat solar irradiance, minimising the probability of photoinhibition, while maximising the absorption of irradiance in cloudy, high-rainfall regions. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Thermocouple, multiple junction reference oven

NASA Technical Reports Server (NTRS)

Leblanc, L. P. (Inventor)

1981-01-01

An improved oven for maintaining the junctions of a plurality of reference thermocouples at a common and constant temperature is described. The oven is characterized by a cylindrical body defining a heat sink with axially extended-cylindrical cavity a singularized heating element which comprises a unitary cylindrical heating element consisting of a resistance heating coil wound about the surface of metallic spool with an axial bore defined and seated in the cavity. Other features of the oven include an annular array of radially extended bores defined in the cylindrical body and a plurality of reference thermocouple junctions seated in the bores in uniformly spaced relation with the heating element, and a temperature sensing device seated in the axial bore for detecting temperature changes as they occur in the spool and circuit to apply a voltage across the coil in response to detected drops in temperatures of the spool.

Critical heat flux test apparatus

DOEpatents

Welsh, Robert E.; Doman, Marvin J.; Wilson, Edward C.

1992-01-01

An apparatus for testing, in situ, highly irradiated specimens at high temperature transients is provided. A specimen, which has a thermocouple device attached thereto, is manipulated into test position in a sealed quartz heating tube by a robot. An induction coil around a heating portion of the tube is powered by a radio frequency generator to heat the specimen. Sensors are connected to monitor the temperatures of the specimen and the induction coil. A quench chamber is located below the heating portion to permit rapid cooling of the specimen which is moved into this quench chamber once it is heated to a critical temperature. A vacuum pump is connected to the apparatus to collect any released fission gases which are analyzed at a remote location.

Temperature distributions measurement of high intensity focused ultrasound using a thin-film thermocouple array and estimation of thermal error caused by viscous heating.

PubMed

Matsuki, Kosuke; Narumi, Ryuta; Azuma, Takashi; Yoshinaka, Kiyoshi; Sasaki, Akira; Okita, Kohei; Takagi, Shu; Matsumoto, Yoichiro

2013-01-01

To improve the throughput of high intensity focused ultrasound (HIFU) treatment, we have considered a focus switching method at two points. For this method, it is necessary to evaluate the thermal distribution under exposure to ultrasound. The thermal distribution was measured using a prototype thin-film thermocouple array, which has the advantage of minimizing the influence of the thermocouple on the acoustic and temperature fields. Focus switching was employed to enlarge the area of temperature increase and evaluate the proposed evaluation parameters with respect to safety and uniformity. The results indicate that focus switching can effectively expand the thermal lesion while maintaining a steep thermal boundary. In addition, the influence caused by the thin-film thermocouple array was estimated experimentally. This thermocouple was demonstrated to be an effective tool for the measurement of temperature distributions induced by HIFU.

Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

2017-01-01

A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.

Incidences of esophageal injury during esophageal temperature monitoring: a comparative study of a multi-thermocouple temperature probe and a deflectable temperature probe in atrial fibrillation ablation.

PubMed

Kuwahara, Taishi; Takahashi, Atsushi; Takahashi, Yoshihide; Okubo, Kenji; Takagi, Katsumasa; Fujino, Tadashi; Kusa, Shigeki; Takigawa, Masateru; Watari, Yuji; Yamao, Kazuya; Nakashima, Emiko; Kawaguchi, Naohiko; Hikita, Hiroyuki; Sato, Akira; Aonuma, Kazutaka

2014-04-01

The study aim was to compare the incidence of esophageal injuries between different temperature probes in the monitoring of esophageal temperature during atrial fibrillation (AF) ablation. One hundred patients with drug-resistant AF were prospectively and randomly assigned into two groups according to the esophageal temperature probe used: the multi-thermocouple probe group (n = 50) and the deflectable temperature probe group (n = 50). Extensive pulmonary vein (PV) isolation was performed with a 3.5-mm open irrigated tip ablation catheter by using a radiofrequency (RF) power of 25-30 W. In both groups, the esophageal temperature thermocouple was placed on the area of the esophagus adjacent to the ablation site. When the esophageal temperature reached 42 °C, the RF energy delivery was stopped. Esophageal endoscopy was performed 1 day after the catheter ablation. No differences existed between the two groups in terms of clinical background and various parameters related to the catheter ablation, including RF delivery time and number of RF deliveries at an esophageal temperature of >42 °C. Esophageal lesions, such as esophagitis and esophageal ulcers, occurred in 10/50 (20 %) and 15/50 (30 %) patients in the multi-thermocouple and deflectable temperature probe groups, respectively (P = 0.25). Most lesions were mild to moderate injuries, and all were cured using conservative treatment. The incidence of esophageal injury was almost equal between the multi-thermocouple temperature probe and the deflectable temperature probe during esophageal temperature monitoring. Most of the esophageal lesions that developed during esophageal temperature monitoring were mild to moderate and reversible.

Introducing Temperature Scales.

ERIC Educational Resources Information Center

McIldowie, Eric

1998-01-01

Ignoring the interpretive problems of temperature measurement deprives students of a beneficial, positive educational experience. Suggests experimenting with different thermometers including a copper resistance thermometer, a thermistor, a thermocouple, and a constant-volume air thermometer. Provides guidance for the classroom discussion of…

Microstructural stability and mechanical behavior of FeNiMnCr high entropy alloy under ion irradiation

DOE PAGES

Leonard, Keith J.; Bei, Hongbin; Zinkle, Steven J.; ...

2016-05-13

In recent years, high entropy alloys (HEAs) have attracted significant attention due to their excellent mechanical properties and good corrosion resistance, making them potential candidates for high temperature fission and fusion structural applications. However there is very little known about their radiation resistance, particularly at elevated temperatures relevant for energy applications. In the present study, a single phase (face centered cubic) concentrated solid solution alloy of composition 27%Fe-28%Ni-27%Mn-18%Cr was irradiated with 3 or 5.8 MeV Ni ions at temperatures ranging from room temperature to 700 °C and midrange doses from 0.03 to 10 displacements per atom (dpa). Transmission electron microscopymore » (TEM), scanning transmission electron microscopy with energy dispersive x-ray spectrometry (STEM/EDS) and X-ray diffraction (XRD) were used to characterize the radiation defects and microstructural changes. Irradiation at higher temperatures showed evidence of relatively sluggish solute diffusion with limited solute depletion or enrichment at grain boundaries. The main microstructural feature at all temperatures was high-density small dislocation loops. Voids were not observed at any irradiation condition. Nano-indentation tests on specimens irradiated at room temperature showed a rapid increase in hardness ~35% and ~80% higher than the unirradiated value at 0.03 and 0.3 dpa midrange doses, respectively. The irradiation-induced hardening was less pronounced for 500 °C irradiations (<20% increase after 3 dpa). Overall, the examined HEA material exhibits superior radiation resistance compared to conventional single phase Fe-Cr-Ni austenitic alloys such as stainless steels. Furthermore, the present study provides insight on the fundamental irradiation behavior of a single phase HEA material over a broad range of irradiation temperatures.« less

Vapor deposition process provides new method for fabricating high temperature thermocouples

NASA Technical Reports Server (NTRS)

Remley, G. A.; Zellner, G. J.

1967-01-01

Fabrication techniques for high temperature thermocouples bind all components so that differential thermal expansion and contraction do not result in mechanical slippage and localized stress concentrations. Installation space is reduced or larger thermoelements and thicker insulation can be used to improve temperature measurement accuracy.

Measuring Thermal Diffusivity Of A High-Tc Superconductor

NASA Technical Reports Server (NTRS)

Powers, Charles E.; Oh, Gloria; Leidecker, Henning

1992-01-01

Technique for measuring thermal diffusivity of superconductor of high critical temperature based on Angstrom's temperature-wave method. Peltier junction generates temperature oscillations, which propagate with attenuation up specimen. Thermal diffusivity of specimen calculated from distance between thermocouples and amplitudes and phases of oscillatory components of thermocouple readings.

Experimental investigation of transient temperature characteristic in high power fiber laser cutting of a thick steel plate

NASA Astrophysics Data System (ADS)

Phi Long, Nguyen; Matsunaga, Yukihiro; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu

2016-10-01

Experiment of temperature measurement was performed to investigate the transient temperature characteristics of molten metal during laser cutting. The aim of this study was to establish a method for measuring the surface temperature variation near the molten pool correlated with changes in cutting parameters. The relationship between temperature inside the kerf cut and characteristic of the cut surface was investigated by using thermography and thermocouples. Results show strong correlations between the transient temperatures and the thermal image for different cutting conditions. In addition, two-color thermometer has been used to obtain radiation intensity emitted from the irradiating zone as a function of operating conditions. Experiments have shown that one can detect the cutting quality by characterization of the surface temperature during laser cutting process.

Modified thermocouple is effective from minus 250 deg to 5000 deg F

NASA Technical Reports Server (NTRS)

Moen, W. K.

1966-01-01

Modified, commercially available thermocouple which measures the temperature of a spacecraft heat shield, is capable of continuous measurement in the range of minus 250 deg to 5000 deg F. The modified thermocouples may be used inside metal treating furnaces in high temperature technology, and in certain corrosive environments.

Multispectral pyrometry for surface temperature measurement of oxidized Zircaloy claddings

NASA Astrophysics Data System (ADS)

Bouvry, B.; Cheymol, G.; Ramiandrisoa, L.; Javaudin, B.; Gallou, C.; Maskrot, H.; Horny, N.; Duvaut, T.; Destouches, C.; Ferry, L.; Gonnier, C.

2017-06-01

Non-contact temperature measurement in a nuclear reactor is still a huge challenge because of the numerous constraints to consider, such as the high temperature, the steam atmosphere, and irradiation. A device is currently developed at CEA to study the nuclear fuel claddings behavior during a Loss-of-Coolant Accident. As a first step of development, we designed and tested an optical pyrometry procedure to measure the surface temperature of nuclear fuel claddings without any contact, under air, in the temperature range 700-850 °C. The temperature of Zircaloy-4 cladding samples was retrieved at various temperature levels. We used Multispectral Radiation Thermometry with the hypothesis of a constant emissivity profile in the spectral ranges 1-1.3 μm and 1.45-1.6 μm. To allow for comparisons, a reference temperature was provided by a thermocouple welded on the cladding surface. Because of thermal losses induced by the presence of the thermocouple, a heat transfer simulation was also performed to estimate the bias. We found a good agreement between the pyrometry measurement and the temperature reference, validating the constant emissivity profile hypothesis used in the MRT estimation. The expanded measurement uncertainty (k = 2) of the temperature obtained by the pyrometry method was ±4 °C, for temperatures between 700 and 850 °C. Emissivity values, between 0.86 and 0.91 were obtained.

Development of Thin Film Thermocouples on Ceramic Materials for Advanced Propulsion System Applications

NASA Technical Reports Server (NTRS)

Holanda, R.

1992-01-01

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 c. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperature of 1500 C depending on the stability of the particular ceramic substrate.

Development of thin film thermocouples on ceramic materials for advanced propulsion system applications

NASA Technical Reports Server (NTRS)

Holanda, Raymond

1993-01-01

Thin film thermocouples were developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hr or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

Refractory thermowell for continuous high temperature measurement of molten metal

DOEpatents

Thiesen, Todd J.

1992-01-01

An apparatus for the continuous high temperature measurement of materials in vessels lined with rammed or cast refractory materials. A refractory housing member is integral with the refractory lining of the vessel and contains a plurality of high temperature sensing means, such as thermocouples. A face of the housing is flush with the refractory lining and contacts the high temperature material contained in the vessel. Continuous temperature measurement is achieved by a means which is coupled to the thermocouples for indicating the temperature.

Steady-state low thermal resistance characterization apparatus: The bulk thermal tester

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burg, Brian R.; Kolly, Manuel; Blasakis, Nicolas

The reliability of microelectronic devices is largely dependent on electronic packaging, which includes heat removal. The appropriate packaging design therefore necessitates precise knowledge of the relevant material properties, including thermal resistance and thermal conductivity. Thin materials and high conductivity layers make their thermal characterization challenging. A steady state measurement technique is presented and evaluated with the purpose to characterize samples with a thermal resistance below 100 mm{sup 2} K/W. It is based on the heat flow meter bar approach made up by two copper blocks and relies exclusively on temperature measurements from thermocouples. The importance of thermocouple calibration is emphasizedmore » in order to obtain accurate temperature readings. An in depth error analysis, based on Gaussian error propagation, is carried out. An error sensitivity analysis highlights the importance of the precise knowledge of the thermal interface materials required for the measurements. Reference measurements on Mo samples reveal a measurement uncertainty in the range of 5% and most accurate measurements are obtained at high heat fluxes. Measurement techniques for homogeneous bulk samples, layered materials, and protruding cavity samples are discussed. Ultimately, a comprehensive overview of a steady state thermal characterization technique is provided, evaluating the accuracy of sample measurements with thermal resistances well below state of the art setups. Accurate characterization of materials used in heat removal applications, such as electronic packaging, will enable more efficient designs and ultimately contribute to energy savings.« less

Temperature monitoring device and thermocouple assembly therefor

DOEpatents

Grimm, Noel P.; Bauer, Frank I.; Bengel, Thomas G.; Kothmann, Richard E.; Mavretish, Robert S.; Miller, Phillip E.; Nath, Raymond J.; Salton, Robert B.

1991-01-01

A temperature monitoring device for measuring the temperature at a surface of a body, composed of: at least one first thermocouple and a second thermocouple; support members supporting the thermocouples for placing the first thermocouple in contact with the body surface and for maintaining the second thermocouple at a defined spacing from the body surface; and a calculating circuit connected to the thermocouples for receiving individual signals each representative of the temperature reading produced by a respective one of the first and second thermocouples and for producing a corrected temperature signal having a value which represents the temperature of the body surface and is a function of the difference between the temperature reading produced by the first thermocouple and a selected fraction of the temperature reading provided by the second thermocouple.

Modelling and control of a diffusion/LPCVD furnace

NASA Astrophysics Data System (ADS)

Dewaard, H.; Dekoning, W. L.

1988-12-01

Heat transfer inside a cylindrical resistance diffusion/Low Pressure Chemical Vapor Deposition (LPCVD) furnace is studied with the aim of developing an improved temperature controller. A model of the thermal behavior is derived, which covers the important class of furnaces equipped with semitransparent quartz process tubes. The model takes into account the thermal behavior of the thermocouples. Currently used temperature controllers are shown to be highly inefficient for very large scale integration applications. Based on the model an alternative temperature controller of the LQG (linear quadratic Gaussian) type is proposed which features direct wafer temperature control. Some simulation results are given.

16 CFR 1505.8 - Maximum acceptable material temperatures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... heat-resistant properties, or if the insulation meets the thermal requirements. 4 40 less than melting... 105 insulation on windings or relays, solenoids, etc.: Thermocouple method 2 90 194 Resistance method 110 230 Class 130 insulation system 110 230 Insulation: Varnished-cloth insulation 85 185 Fiber used...

16 CFR 1505.8 - Maximum acceptable material temperatures.

Code of Federal Regulations, 2010 CFR

2010-01-01

... heat-resistant properties, or if the insulation meets the thermal requirements. 4 40 less than melting... 105 insulation on windings or relays, solenoids, etc.: Thermocouple method 2 90 194 Resistance method 110 230 Class 130 insulation system 110 230 Insulation: Varnished-cloth insulation 85 185 Fiber used...

16 CFR 1505.8 - Maximum acceptable material temperatures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... heat-resistant properties, or if the insulation meets the thermal requirements. 4 40 less than melting... 105 insulation on windings or relays, solenoids, etc.: Thermocouple method 2 90 194 Resistance method 110 230 Class 130 insulation system 110 230 Insulation: Varnished-cloth insulation 85 185 Fiber used...

16 CFR 1505.8 - Maximum acceptable material temperatures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... heat-resistant properties, or if the insulation meets the thermal requirements. 4 40 less than melting... 105 insulation on windings or relays, solenoids, etc.: Thermocouple method 2 90 194 Resistance method 110 230 Class 130 insulation system 110 230 Insulation: Varnished-cloth insulation 85 185 Fiber used...

Heat-Conducting Anchors for Thermocouples

NASA Technical Reports Server (NTRS)

Macdavid, Kenton S.

1987-01-01

Metal particles in adhesive aid heat transfer. Aluminum caps containing silver-filled epoxy used as high-thermal-conductance anchors for thermocouples, epoxy providing thermal path between mounting surfaces and thermocouple measuring junctions. Normally, epoxy-filled aluminum caps used when measuring steady-state temperatures. Silver-filled epoxy used when thermocouple not isolated electrically from surface measured.

Unique thermocouple to measure the temperatures of squibs, igniters, propellants, and rocket nozzles

NASA Astrophysics Data System (ADS)

Nanigian, Jacob; Nanigian, Dan

2006-05-01

The temperatures produced by the various components in the propulsion system of rockets and missiles determine the performance of the rocket. Since these temperatures occur very rapidly and under extreme conditions, standard thermocouples fail before any meaningful temperatures are measured. This paper describes the features of a special family of high performance thermocouples, which can measure these transient temperatures with millisecond response times and under the most severe conditions of erosion. Examples of igniter, propellant and rocket nozzle temperatures are included in this paper. Also included is heat flux measurements made by these sensors in rocket applications.

16 CFR § 1505.8 - Maximum acceptable material temperatures.

Code of Federal Regulations, 2013 CFR

2013-01-01

... heat-resistant properties, or if the insulation meets the thermal requirements. 4 40 less than melting... 105 insulation on windings or relays, solenoids, etc.: Thermocouple method 2 90 194 Resistance method 110 230 Class 130 insulation system 110 230 Insulation: Varnished-cloth insulation 85 185 Fiber used...

Material Problems in Using High-Temperature Thermocouples

NASA Astrophysics Data System (ADS)

Edler, F.

2011-08-01

The material compatibility and thermal stability of ceramic-composite coatings of different oxide ceramics deposited on alumina tubes to prevent the reduction of the alumina were investigated in the high-temperature range between 1750 °C and 1850 °C. It turned out that the coatings were thermally unstable and did not provide adequate protection against the reduction of the alumina tubes. The oxide ceramics formed eutectic compositions with low melting temperatures and were also prone to reduction to elementary metals by carbon. A new type of high-temperature thermocouple on the basis of refractory and noble metals was tested in the temperature range between 1325 °C and 1800 °C. Two metal-sheathed prototypes were constructed. The thermoelectric behavior of the tungsten5%rhenium/iridium thermocouples (W5%Re/Ir) was investigated by different high-temperature exposures, and the thermoelectric stability was checked by repeated measurements at the ice point.

System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages

NASA Technical Reports Server (NTRS)

Anderson, Karl F. (Inventor); Parker, Allen R., Jr. (Inventor)

1993-01-01

A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reverser generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reverser, and determining the temperature of the sensor responsive to the first and second measured voltages.

Temperature Sensor

NASA Technical Reports Server (NTRS)

1980-01-01

Weed Instrument Inc. produces a line of thermocouples - temperature sensors - for a variety of industrial and research uses. One of the company's newer products is a thermocouple specially designed for high accuracy at extreme temperatures above 3,000 degrees Fahrenheit. Development of sensor brought substantial increases in Weed Instrument sales and employment.

Self-validating type C thermocouples to 2300 °C using high temperature fixed points

NASA Astrophysics Data System (ADS)

Pearce, J. V.; Elliott, C. J.; Machin, G.; Ongrai, O.

2013-09-01

Above 1500 °C, tungsten-rhenium (W-Re) thermocouples are the most commonly used contact thermometers because they are practical and inexpensive. However in general loss of calibration is very rapid, and, due to their embrittlement at high temperature, it is generally not possible to remove them for recalibration from the process environments in which they are used. Even if removal for recalibration was possible this would be of, at best, very limited use due to large inhomogeneity effects. Ideally, these thermocouples require some mechanism to monitor their drift in-situ. In this study, we describe self-validation of Type C (W5%Re/W26%Re) thermocouples by means of miniature high temperature fixed points comprising crucibles containing respectively Co-C, Pt-C, Ru-C, and Ir-C eutectic alloys. An overview of developments in this area is presented.

Design and Operation of a Fast, Thin-Film Thermocouple Probe on a Turbine Engine

NASA Technical Reports Server (NTRS)

Meredith, Roger D.; Wrbanek, John D.; Fralick, Gustave C.; Greer, Lawrence C., III; Hunter, Gary W.; Chen, Liang-Yu

2014-01-01

As a demonstration of technology maturation, a thin-film temperature sensor probe was fabricated and installed on a F117 turbofan engine via a borescope access port to monitor the temperature experienced in the bleed air passage of the compressor area during an engine checkout test run. To withstand the harsh conditions experienced in this environment, the sensor probe was built from high temperature materials. The thin-film thermocouple sensing elements were deposited by physical vapor deposition using pure metal elements, thus avoiding the inconsistencies of sputter-depositing particular percentages of materials to form standardized alloys commonly found in thermocouples. The sensor probe and assembly were subjected to a strict protocol of multi-axis vibrational testing as well as elevated temperature pressure testing to be qualified for this application. The thin-film thermocouple probe demonstrated a faster response than a traditional embedded thermocouple during the engine checkout run.

Improved Blackbody Temperature Sensors for a Vacuum Furnace

NASA Technical Reports Server (NTRS)

Farmer, Jeff; Coppens, Chris; O'Dell, J. Scott; McKechnie, Timothy N.; Schofield, Elizabeth

2009-01-01

Some improvements have been made in the design and fabrication of blackbody sensors (BBSs) used to measure the temperature of a heater core in a vacuum furnace. Each BBS consists of a ring of thermally conductive, high-melting-temperature material with two tantalum-sheathed thermocouples attached at diametrically opposite points. The name "blackbody sensor" reflects the basic principle of operation. Heat is transferred between the ring and the furnace heater core primarily by blackbody radiation, heat is conducted through the ring to the thermocouples, and the temperature of the ring (and, hence, the temperature of the heater core) is measured by use of the thermocouples. Two main requirements have guided the development of these BBSs: (1) The rings should have as high an emissivity as possible in order to maximize the heat-transfer rate and thereby maximize temperature-monitoring performance and (2) the thermocouples must be joined to the rings in such a way as to ensure long-term, reliable intimate thermal contact. The problem of fabricating a BBS to satisfy these requirements is complicated by an application-specific prohibition against overheating and thereby damaging nearby instrumentation leads through the use of conventional furnace brazing or any other technique that involves heating the entire BBS and its surroundings. The problem is further complicated by another application-specific prohibition against damaging the thin tantalum thermocouple sheaths through the use of conventional welding to join the thermocouples to the ring. The first BBS rings were made of graphite. The tantalum-sheathed thermocouples were attached to the graphite rings by use of high-temperature graphite cements. The ring/thermocouple bonds thus formed were found to be weak and unreliable, and so graphite rings and graphite cements were abandoned. Now, each BBS ring is made from one of two materials: either tantalum or a molybdenum/titanium/zirconium alloy. The tantalum-sheathed thermocouples are bonded to the ring by laser brazing. The primary advantage of laser brazing over furnace brazing is that in laser brazing, it is possible to form a brazed connection locally, without heating nearby parts to the flow temperature of the brazing material. Hence, it is possible to comply with the prohibition against overheating nearby instrumentation leads. Also, in laser brazing, unlike in furnace brazing, it is possible to exert control over the thermal energy to such a high degree that it becomes possible to braze the thermocouples to the ring without burning through the thin tantalum sheaths on the thermocouples. The brazing material used in the laser brazing process is a titanium-boron paste. This brazing material can withstand use at temperatures up to about 1,400 C. In thermal-cycling tests performed thus far, no debonding between the rings and thermocouples has been observed. Emissivity coatings about 0.001 in. (.0.025 mm) thick applied to the interior surfaces of the rings have been found to improve the performance of the BBS sensors by raising the apparent emissivities of the rings. In thermal-cycling tests, the coatings were found to adhere well to the rings.

Intrapulpal temperatures during pulsed Nd:YAG laser treatment of dentin, in vitro.

PubMed

White, J M; Fagan, M C; Goodis, H E

1994-03-01

Lasers are being used for soft tissue removal, caries removal, and treatment of root surface sensitivity. One concern for laser safety is that the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occur during gingival excision, superficial caries removal, and modification of the dentin surface for treatment of root surface sensitivity, a 2 mm2 area of the external root surface was uniformly irradiated with a pulsed Nd:YAG laser using a 320 microns diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high speed handpiece with air coolant were also recorded. Repeated measures ANOVA (P < or = 0.05) indicated that intrapulpal temperatures increased as a function of power, frequency, and time. Intrapulpal temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd:YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, should not cause devitalizing intrapulpal temperature rises.

Thermocouple-Signal-Conditioning Circuit

NASA Technical Reports Server (NTRS)

Simon, Richard A.

1991-01-01

Thermocouple-signal-conditioning circuit acting in conjunction with thermocouple, exhibits electrical behavior of voltage in series with resistance. Combination part of input bridge circuit of controller. Circuit configured for either of two specific applications by selection of alternative resistances and supply voltages. Includes alarm circuit detecting open circuit in thermocouple and provides off-scale output to signal malfunctions.

Modeling and control of diffusion and low-pressure chemical vapor deposition furnaces

NASA Astrophysics Data System (ADS)

De Waard, H.; De Koning, W. L.

1990-03-01

In this paper a study is made of the heat transfer inside cylindrical resistance diffusion and low-pressure chemical vapor deposition furnaces, aimed at developing an improved temperature controller. A model of the thermal behavior is derived which also covers the important class of furnaces equipped with semitransparent quartz process tubes. The model takes into account the thermal behavior of the thermocouples. It is shown that currently used temperature controllers are highly inefficient for very large scale integration applications. Based on the model an alternative temperature controller of the linear-quadratic-Gaussian type is proposed which features direct wafer temperature control. Some simulation results are given.

High temperature thermocouple development program, part A and part B

NASA Technical Reports Server (NTRS)

Toenshoff, D. A.; Zysk, E. D.; Fleischner, P. L.

1972-01-01

The problem of extending the useful life of thermocouples intended for in-core and out-of-core thermionic applications in a vacuum environment at temperatures up to 2273 K for periods of time up to 10,000 hours was investigated. Many factors that may influence this useful life were examined, and a basic probe design was developed. With a few modifications, twenty-three thermocouple assemblies were fabricated. Generally the finished thermocouple consisted of solid doped W-3% Re and W-25% Re wires and high purity and high density BeO insulators, and was sheathed in a high purity tantalum tube. In a few probes, stranded thermocouple wires were substituted; commercial grade BeO was used; and in two cases, CVD W-22% Re tubing was used. Each of the components was made of the highest purity materials available; was subjected to special cleaning steps, and was assembled in a class 10,000 clean room. Pertinent physical and chemical properties were determined on each of the components. Special processing techniques were used in the fabrication of the high purity (99.95%), high density (over 95% of theoretical) BeO.

Annealing Increases Stability Of Iridium Thermocouples

NASA Technical Reports Server (NTRS)

Germain, Edward F.; Daryabeigi, Kamran; Alderfer, David W.; Wright, Robert E.; Ahmed, Shaffiq

1989-01-01

Metallurgical studies carried out on samples of iridium versus iridium/40-percent rhodium thermocouples in condition received from manufacturer. Metallurgical studies included x-ray, macroscopic, resistance, and metallographic studies. Revealed large amount of internal stress caused by cold-working during manufacturing, and large number of segregations and inhomogeneities. Samples annealed in furnace at temperatures from 1,000 to 2,000 degree C for intervals up to 1 h to study effects of heat treatment. Wire annealed by this procedure found to be ductile.

Attaching Thermocouples by Peening or Crimping

NASA Technical Reports Server (NTRS)

Murtland, Kevin; Cox, Robert; Immer, Christopher

2006-01-01

Two simple, effective techniques for attaching thermocouples to metal substrates have been devised for high-temperature applications in which attachment by such conventional means as welding, screws, epoxy, or tape would not be effective. The techniques have been used successfully to attach 0.005- in. (0.127-mm)-diameter type-S thermocouples to substrates of niobium alloy C-103 and stainless steel 416 for measuring temperatures up to 2,600 F (1,427 C). The techniques are equally applicable to other thermocouple and substrate materials. In the first technique, illustrated in the upper part of the figure, a hole slightly wider than twice the diameter of one thermocouple wire is drilled in the substrate. The thermocouple is placed in the hole, then the edge of the hole is peened in one or more places by use of a punch (see figure). The deformed material at the edge secures the thermocouple in the hole. In the second technique a hole is drilled as in the first technique, then an annular relief area is machined around the hole, resulting in structure reminiscent of a volcano in a crater. The thermocouple is placed in the hole as in the first technique, then the "volcano" material is either peened by use of a punch or crimped by use of sidecutters to secure the thermocouple in place. This second technique is preferable for very thin thermocouples [wire diameter .0.005 in. (.0.127 mm)] because standard peening poses a greater risk of clipping one or both of the thermocouple wires. These techniques offer the following advantages over prior thermocouple-attachment techniques: . Because these techniques involve drilling of very small holes, they are minimally invasive . an important advantage in that, to a first approximation, the thermal properties of surrounding areas are not appreciably affected. . These techniques do not involve introduction of any material, other than the substrate and thermocouple materials, that could cause contamination, could decompose, or oxidize at high measurement temperatures. . The simplicity of these techniques makes it possible to attach thermocouples quickly. . These techniques can be used to attach thermocouples at locations where access is somewhat restricted by the surrounding objects.

46 CFR 164.009-11 - Furnace apparatus.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., and three thermocouples (a furnace thermocouple to measure furnace temperature, a surface thermocouple to measure temperature at the surface of a specimen, and a specimen thermocouple to measure... apparatus may be obtained from the Commandant (CG-521). (b) Temperatures measured by the thermocouples are...

46 CFR 164.009-11 - Furnace apparatus.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., and three thermocouples (a furnace thermocouple to measure furnace temperature, a surface thermocouple to measure temperature at the surface of a specimen, and a specimen thermocouple to measure... apparatus may be obtained from the Commandant (CG-521). (b) Temperatures measured by the thermocouples are...

46 CFR 164.009-11 - Furnace apparatus.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., and three thermocouples (a furnace thermocouple to measure furnace temperature, a surface thermocouple to measure temperature at the surface of a specimen, and a specimen thermocouple to measure... apparatus may be obtained from the Commandant (CG-521). (b) Temperatures measured by the thermocouples are...

Characterization of a Method for Inverse Heat Conduction Using Real and Simulated Thermocouple Data

NASA Technical Reports Server (NTRS)

Pizzo, Michelle E.; Glass, David E.

2017-01-01

It is often impractical to instrument the external surface of high-speed vehicles due to the aerothermodynamic heating. Temperatures can instead be measured internal to the structure using embedded thermocouples, and direct and inverse methods can then be used to estimate temperature and heat flux on the external surface. Two thermocouples embedded at different depths are required to solve direct and inverse problems, and filtering schemes are used to reduce noise in the measured data. Accuracy in the estimated surface temperature and heat flux is dependent on several factors. Factors include the thermocouple location through the thickness of a material, the sensitivity of the surface solution to the error in the specified location of the embedded thermocouples, and the sensitivity to the error in thermocouple data. The effect of these factors on solution accuracy is studied using the methodology discussed in the work of Pizzo, et. al.1 A numerical study is performed to determine if there is an optimal depth at which to embed one thermocouple through the thickness of a material assuming that a second thermocouple is installed on the back face. Solution accuracy will be discussed for a range of embedded thermocouple depths. Moreover, the sensitivity of the surface solution to (a) the error in the specified location of the embedded thermocouple and to (b) the error in the thermocouple data are quantified using numerical simulation, and the results are discussed.

Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

NASA Astrophysics Data System (ADS)

Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; Deck, Christian P.; Katoh, Yutai; Terrani, Kurt A.

2017-08-01

The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300-350 °C under a representative high heat flux (∼0.66 MW/m2) during one cycle of irradiation in an un-instrumented ;rabbit; capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. The success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.

Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.

The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300–350 °C under a representative high heat flux (~0.66 MW/m 2) during one cycle of irradiation in an un-instrumented “rabbit” capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb themore » expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. Furthermore, the success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.« less

Self-Validating Thermocouples for Assured Measurement Confidence and Extended Useful Life

NASA Astrophysics Data System (ADS)

Elliott, C. J.; Pearce, J. V.; Machin, G.; Schwarz, C.; Lindner, R.

2012-07-01

Accurate measurements of temperatures above 1500 °C pose unique and challenging requirements in space. Tungsten-rhenium (W-Re) thermocouples, which are commonly used, quickly exhibit significant thermoelectric inhomogeneity and drift. To address this issue, the National Physical Laboratory in cooperation with ESA/ESTEC is developing an innovative method of validating the performance of high-temperature thermocouples in-situ. The results of measurements using eutectic metal-carbon fixed-point cells containing Co-C (~1324 °C), Pt-C (~1738 °C), Ru-C (~1953 °C) and Ir-C (~2292°C) ingots incorporated onto the thermocouple in use are presented. By monitoring the thermoelectric signal each time the thermal environment passes through the melting temperature of the ingot, the user observes the degree of drift. This assures measurement confidence and extends the useful life of the thermocouple as the drift may be corrected for, if necessary. This approach opens the possibility for improved temperature measurement for ESA/ESTEC research applications and industrial use.

Development of an Integrated Thermocouple for the Accurate Sample Temperature Measurement During High Temperature Environmental Scanning Electron Microscopy (HT-ESEM) Experiments.

PubMed

Podor, Renaud; Pailhon, Damien; Ravaux, Johann; Brau, Henri-Pierre

2015-04-01

We have developed two integrated thermocouple (TC) crucible systems that allow precise measurement of sample temperature when using a furnace associated with an environmental scanning electron microscope (ESEM). Sample temperatures measured with these systems are precise (±5°C) and reliable. The TC crucible systems allow working with solids and liquids (silicate melts or ionic liquids), independent of the gas composition and pressure. These sample holder designs will allow end users to perform experiments at high temperature in the ESEM chamber with high precision control of the sample temperature.

High Speed Surface Thermocouples Interface to Wireless Transmitters

DTIC Science & Technology

2017-03-15

Government and/or Private Sector Use Being able to measure high-speed surface temperatures in hostile environments where wireless transmission of the data...09/16/2016 See Item 16 Draft Reg Repro 16. REMARKS Eric Gingrich, COR I Item 0: High Speed Surface Thermocouples Interface to Wireless ...Speed Surface Thermocouples Interface to Wireless Transmitters W56HZV-16-C-0149 Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT

Thermal Stability of RP-2 for Hydrocarbon Boost Regenerative Cooling

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie E.; Deans, Matthew C.; Stiegemeier, Benjamin R.; Psaras, Peter M.

2013-01-01

A series of tests were performed in the NASA Glenn Research Centers Heated Tube Facility to study the heat transfer and thermal stability behavior of RP-2 under conditions similar to those found in rocket engine cooling channels. It has long been known that hydrocarbon fuels, such as RP-2, can decompose at high temperature to form deposits (coke) which can adversely impact rocket engine cooling channel performance. The heated tube facility provides a simple means to study these effects. Using resistively heated copper tubes in a vacuum chamber, flowing RP-2 was heated to explore thermal effects at a range of test conditions. Wall temperature (850-1050F) and bulk fluid temperature (300-500F) were varied to define thermal decomposition and stability at each condition. Flow velocity and pressure were fixed at 75 fts and 1000 psia, respectively. Additionally, five different batches of RP-2 were tested at identical conditions to examine any thermal stability differences resulting from batch to batch compositional variation. Among these tests was one with a potential coke reducing additive known as 1,2,3,4-Tetrahydroquinoline (THQ). While copper tubes were used for the majority of tests, two exploratory tests were performed with a copper alloy known as GRCop-42. Each tube was instrumented with 15 thermocouples to examine the temperature profile, and carbon deposition at each thermocouple location was determined post-test in an oxidation furnace. In many tests, intermittent local temperature increases were observed visually and in the thermocouple data. These hot spots did not appear to correspond with a higher carbon deposition.

46 CFR 164.007-6 - Test report.

Code of Federal Regulations, 2012 CFR

2012-10-01

... temperature, for each thermocouple together with curves of average temperature for the unexposed surface of the insulation and the thermocouple recording the highest temperature. In addition, for § 164.007-9(g... and each surface of insulation thermocouple together with the initial temperature of each thermocouple...

46 CFR 164.007-6 - Test report.

Code of Federal Regulations, 2013 CFR

2013-10-01

... temperature, for each thermocouple together with curves of average temperature for the unexposed surface of the insulation and the thermocouple recording the highest temperature. In addition, for § 164.007-9(g... and each surface of insulation thermocouple together with the initial temperature of each thermocouple...

Temperature Rise during Primer, Adhesive, and Composite Resin Photopolymerization of a Low-Shrinkage Composite Resin under Caries-Like Dentin Lesions

PubMed Central

Mousavinasab, Sayed-Mostafa; Khoroushi, Maryam; Moharreri, Mohammadreza

2012-01-01

Objective. This study evaluated temperature rise of low-shrinkage (LS) self-etch primer (P), LS self-etch adhesive (A), and P90 silorane-based composite resin systems, photopolymerized under normal and artificially demineralized dentin. Methods. Forty 1.5 mm-thick dentin discs were prepared from sound human molars, half of which were demineralized. Temperature rise was measured during photopolymerization using a K-type thermocouple under the discs: 10 s and 40 s irradiation of the discs (controls/groups 1 and 2); 10 s irradiation of primer (P), 10 s irradiation of adhesive (A), 40 s irradiation of P90 without P and A, and 40 s irradiation of P90 with P and A (groups 3 to 6, resp.). The samples were photopolymerized using an LED unit under 550 mW/cm2 light intensity. Data was analyzed using repeated measures ANOVA and paired-sample t-test (α = 0.05). Results. There were no significant differences in temperature rise means between the two dentin samples for each irradiation duration (P > 0.0001), with significant differences between the two irradiation durations (P > 0.0001). Temperature rise measured with 40 s irradiation was significantly higher than that of 10 s duration for undemineralized and demineralized dentin P < 0.0001). Conclusions. Light polymerization of P90 low-shrinkage composite resin resulted in temperature rise approaching threshold value under artificially demineralized and undemineralized dentin. PMID:23320185

Probe with integrated heater and thermocouple pack

DOEpatents

McCulloch, Reginald W.; Dial, Ralph E.; Finnell, Wilber K. R.

1988-01-01

A probe for measuring heat includes an elongate rod fitted within a sheath, and a plurality of annular recesses are formed on the surface of the rod in a spaced-apart relationship to form annular chambers that are resistant to heat flow. A longitudinal bore extends axially into the rod and within the cylinders defined by the annular chambers, and an integrated heater and thermocouple pack is dimensioned to fit within the bore. In construction, the integrated pack includes a plurality of wires disposed in electrical insulation within a sheath and a heater cable. These wires include one common wire and a plurality of thermocouple wires. The common wire is constructed of one type of conductive material while the thermocouple wires are each constructed of two types of materials so that at least one thermocouple junction is formed therein. All of the wires extend the length of the integrated pack and are connected together at their ends. The thermocouple wires are constructed to form thermocouple junctions proximate to each annular chamber for producing electromotive forces corresponding to the temperature of the rod within the annular chambers relative to outside the chambers. In the preferred embodiment, each thermocouple wire forms two thermocouple junctions, one junction being disposed within an annular chamber and the second junction being disposed outside of, but proximate to, the same annular chamber. In one embodiment two thermocouple wires are configured to double the sensitivity of the probe in one region.

[Problems of using a thermocouple for measurements of skin temperature rise during the exposure to millimeter waves].

PubMed

Alekseev, S I; Ziskin, M S; Fesenko, E E

2011-01-01

The possibility of using thermocouples for the artifact-free measurements of skin temperature during millimeter wave exposure was studied. The distributions of the specific absorption rate (SAR) in the human skin were calculated for different orientations of the thermocouple relative to the E-field of exposure. It was shown that, at the parallel orientation of a thermocouple relative to the E-field, SAR significantly increased at the tip of the thermocouple. This can result in an overheating of the thermocouple. At the perpendicular orientation of a thermocouple, the distortions of the SAR were insignificant. The data obtained confirm that the skin temperature can be measured with a thermocouple during exposure under the condition that the thermocouple is located perpendicular to the E-vector of the electromagnetic field. For the accurate determination of SAR from the rate of the initial temperature rise, it is necessary to fit the temperature kinetics measured with the thermocouple to the solution of the bio-heat transfer equation.

In situ field measurement of leaf water potential using thermocouple psychrometers.

PubMed

Savage, M J; Wiebe, H H; Cass, A

1983-11-01

Thermocouple psychrometers are the only instruments which can measure the in situ water potential of intact leaves, and which can possibly be used to monitor leaf water potential. Unfortunately, their usefulness is limited by a number of difficulties, among them fluctuating temperatures and temperature gradients within the psychrometer, sealing of the psychrometer chamber to the leaf, shading of the leaf by the psychrometer, and resistance to water vapor diffusion by the cuticle when the stomates are closed. Using Citrus jambhiri, we have tested several psychrometer design and operational modifications and showed that in situ psychrometric measurements compared favorably with simultaneous Scholander pressure chamber measurements on neighboring leaves when the latter were corrected for the osmotic potential.

Effects of high-energy proton irradiation on the superconducting properties of Fe(Se,Te) thin films

NASA Astrophysics Data System (ADS)

Sylva, G.; Bellingeri, E.; Ferdeghini, C.; Martinelli, A.; Pallecchi, I.; Pellegrino, L.; Putti, M.; Ghigo, G.; Gozzelino, L.; Torsello, D.; Grimaldi, G.; Leo, A.; Nigro, A.; Braccini, V.

2018-05-01

In this paper we explore the effects of 3.5 MeV proton irradiation on Fe(Se,Te) thin films grown on CaF2. In particular, we carry out an experimental investigation with different irradiation fluences up to 7.30 · 1016 cm‑2 and different proton implantation depths, in order to clarify whether and to what extent the critical current is enhanced or suppressed, what are the effects of irradiation on the critical temperature, resistivity, and critical magnetic fields, and finally what is the role played by the substrate in this context. We find that the effect of irradiation on superconducting properties is generally small compared to the case of other iron-based superconductors. The irradiation effect is more evident on the critical current density Jc, while it is minor on the transition temperature Tc, normal state resistivity ρ, and on the upper critical field Hc2 up to the highest fluences explored in this work. In more detail, our analysis shows that when protons implant in the substrate far from the superconducting film, the critical current can be enhanced up to 50% of the pristine value at 7 T and 12 K; meanwhile, there is no appreciable effect on critical temperature and critical fields together with a slight decrease in resistivity. On the contrary, when the implantation layer is closer to the film–substrate interface, both critical current and temperature show a decrease accompanied by an enhancement of the resistivity and lattice strain. This result evidences that possible modifications induced by irradiation in the substrate may affect the superconducting properties of the film via lattice strain. The robustness of the Fe(Se,Te) system to irradiation-induced damage makes it a promising compound for the fabrication of magnets in high-energy accelerators.

A coaxial thermocouple for shock tunnel applications.

PubMed

Menezes, Viren; Bhat, Sandeep

2010-10-01

A chromel-constantan coaxial surface junction thermocouple has been designed, fabricated, calibrated, and tested to measure the temperature-time history on the surface of a body in a hypersonic freestream of Mach 8 in a shock tunnel. The coaxial thermocouple with a diameter of 3.25 mm was flush mounted in the surface of a hemisphere of 25 mm diameter. The hypersonic freestream was of a very low temperature and density, and had a flow time of about a millisecond. Preliminary test results indicate that the thermocouple is quite sensitive to low temperature-rarefied freestreams, and also has a response time of a few microseconds (≈5 μs) to meet the requirements of short duration transient measurements. The sensor developed is accurate, robust, reproducible, and is highly inexpensive.

A Portable, Shock-Proof, Surface-Heated Droplet PCR System for Escherichia coli Detection

PubMed Central

Angus, Scott V.; Cho, Soohee; Harshman, Dustin K.; Song, Jae-Young; Yoon, Jeong-Yeol

2015-01-01

A novel polymerase chain reaction (PCR) device was developed that uses wire-guided droplet manipulation (WDM) to guide a droplet over three different heating chambers. After PCR amplification, end-point detection is achieved using a smartphone-based fluorescence microscope. The device was tested for identification of the 16S rRNA gene V3 hypervariable region from Escherichia coli genomic DNA. The lower limit of detection was 103 genome copies per sample. The device is portable with smartphone-based end-point detection and provides the assay results quickly (15 min for a 30-cycle amplification) and accurately. The system is also shock and vibration resistant, due to the multiple points of contact between the droplet and the thermocouple and the Teflon film on the heater surfaces. The thermocouple also provides realtime droplet temperature feedback to ensure it reaches the set temperature before moving to the next chamber/step in PCR. The device is equipped to use either silicone oil or coconut oil. Coconut oil provides additional portability and ease of transportation by eliminating spilling because its high melting temperature means it is solid at room temperature. PMID:26164008

In vitro photodynamic antimicrobial chemotherapy in dentine contaminated by cariogenic bacteria

NASA Astrophysics Data System (ADS)

Melo, M. A. S.; de-Paula, D. M.; Lima, J. P. M.; Borges, F. M. C.; Steiner-Oliveira, C.; Nobre-Dos-Santos, M.; Zanin, I. C. J.; Barros, E. B.; Rodrigues, L. K. A.

2010-06-01

The development of a method to ensure bacterial-free substrates without extensive cavity preparation would be highly useful to dentistry, since there is no currently available effective method for killing residual bacteria in dentinal tissue. This randomized in vitro study determined parameters for using toluidine blue O (TBO) with a light-emitting diode (LED) for dentine caries disinfection and monitored intrapulpal/periodontal temperatures during irradiation. Occlusal human dentine slabs were immersed in Streptococcus mutans culture for demineralization induction. Slabs were allocated to 10 groups ( n = 15), which were treated with 0.1 mg ml-1 TBO with 5 min of incubation time or 0.9% NaCl solution for 5, 10 or 15 min, and submitted or not to irradiation for 5, 10 or 15 min (47, 94, and 144 J/cm2). Before and after treatments, dentine samples were analyzed with regard to S. mutans counts. In whole teeth, temperature in pulp and periodontium was measured by thermocouples during irradiation. Kruskal-Wallis/Student-Newman-Keuls, and ANOVA/Tukey test were respectively utilized to compare log reductions and temperature rises between groups. Bacterial reduction was observed when dentine was exposed to both TBO and LED at all irradiation times, as well as to LED alone for 10 and 15 min. Temperature increases lower than 2°C were observed for either pulp or periodontium. Concluding, LED combined with TBO is a safe and effective approach for dentine caries disinfection. Nevertheless, additional studies should be conducted to determine the influence of the irradiation in S. mutans viability in dentinal surface/tubules.

Improved performance characteristics of a high temperature superconductor bolometer using photo-thermoelectrical feedback

NASA Astrophysics Data System (ADS)

Kaila, M. M.; Russell, G. J.

2000-12-01

We have designed a liquid nitrogen cooled detector where a thermoelectric feedback is combined with electrothermal feedback to produce an improvement of three orders of magnitude in the response time of the detector. We have achieved this by considering a parallel resistance combination of thermoelectric and High Temperature Superconductor (HTSC) material legs of an approximate geometry 1mm /spl times/ 2 mm /spl times/ 1micron operated at 80K. One end of this thermocouple acts as the sensitive area where the radiation is absorbed. The other end remains unexposed and stays basically at substrate temperature. It is found that micron thick films in our bolometer produce characteristics very close to those found for nanometer thick films required in semiconductor detectors and Low Temperature Superconductor (LTSC) bolometers.

High Accuracy Temperature Measurements Using RTDs with Current Loop Conditioning

NASA Technical Reports Server (NTRS)

Hill, Gerald M.

1997-01-01

To measure temperatures with a greater degree of accuracy than is possible with thermocouples, RTDs (Resistive Temperature Detectors) are typically used. Calibration standards use specialized high precision RTD probes with accuracies approaching 0.001 F. These are extremely delicate devices, and far too costly to be used in test facility instrumentation. Less costly sensors which are designed for aeronautical wind tunnel testing are available and can be readily adapted to probes, rakes, and test rigs. With proper signal conditioning of the sensor, temperature accuracies of 0.1 F is obtainable. For reasons that will be explored in this paper, the Anderson current loop is the preferred method used for signal conditioning. This scheme has been used in NASA Lewis Research Center's 9 x 15 Low Speed Wind Tunnel, and is detailed.

Comparisons of Gas-phase Temperature Measurements in a Flame Using Thin-Filament Pyrometry and Thermocouples

NASA Technical Reports Server (NTRS)

Struk, Peter; Dietrich, Daniel; Valentine, Russell; Feier, Ioan

2003-01-01

Less-intrusive, fast-responding, and full-field temperature measurements have long been a desired tool for the research community. Recently, the emission of a silicon-carbide (SiC) fiber placed in a flowing hot (or reacting) gas has been used to measure the temperature profile along the length of the fiber. The relationship between the gas and fiber temperature comes from an energy balance on the fiber. In the present work, we compared single point flame temperature measurements using thin-filament pyrometry (TFP) and thermocouples. The data was from vertically traversing a thermocouple and a SiC fiber through a methanol/air diffusion flame of a porous-metal wick burner. The results showed that the gas temperature using the TFP technique agreed with the thermocouple measurements (25.4 m diameter wire) within 3.5% for temperatures above 1200 K. Additionally, we imaged the entire SiC fiber (with a spatial resolution of 0.14 mm) while it was in the flame using a high resolution CCD camera. The intensity level along the fiber length is a function of the temperature. This results in a one-dimensional temperature profiles at various heights above the burner wick. This temperature measurement technique, while having a precision of less than 1 K, showed data scatter as high as 38 K. Finally, we discuss the major sources of uncertainty in gas temperature measurement using TFP.

Irradiation effect of the insulating materials for fusion superconducting magnets at cryogenic temperature

NASA Astrophysics Data System (ADS)

Kobayashi, Koji; Akiyama, Yoko; Nishijima, Shigehiro

2017-09-01

In ITER, superconducting magnets should be used in such severe environment as high fluence of fast neutron, cryogenic temperature and large electromagnetic forces. Insulating material is one of the most sensitive component to radiation. So radiation resistance on mechanical properties at cryogenic temperature are required for insulating material. The purpose of this study is to evaluate irradiation effect of insulating material at cryogenic temperature by gamma-ray irradiation. Firstly, glass fiber reinforced plastic (GFRP) and hybrid composite were prepared. After irradiation at room temperature (RT) or liquid nitrogen temperature (LNT, 77 K), interlaminar shear strength (ILSS) and glass-transition temperature (Tg) measurement were conducted. It was shown that insulating materials irradiated at room temperature were much degraded than those at cryogenic temperature.

Probe with integrated heater and thermocouple pack

DOEpatents

McCulloch, Reg W.; Dial, Ralph E.; Finnell, Wilber K. R.

1990-01-01

A probe for measuring heat includes an elongate rod fitted within a sheath, and a plurality of annular recesses are formed on the surface of the rod in a spaced-apart relationship to form annular chambers that are resistant to heat flow. A longitudinal bore extends axially into the rod and within the cylinders defined by the annular chambers, and an integrated heater and thermocouple pack is dimensioned to fit within the bore. In construction, the integrated pack includes a plurality of wires disposed in electrical insulation within a sheath and a heater cable. These wires include one common wire and a plurality of thermocuple wires. The common wire is constructed of one type of conductive material while the thermocouple wires are each constructed of two types of materials so that at least one thermocouple junction is formed therein. All of the wires extend the length of the integrated pack and are connected together at their ends. The thermocouple wires are constructed to form thermocouple junctions proximate to each annular chamber for producing electromotive forces corresponding to the temperature of the rod within the annular chambers relative to outside the chambers. In the preferred embodiment, each thermocouple wire forms two thermocouple junctions, one junction being disposed within an annular chamber and the second junction being disposed outside of, but proximate to, the same annular chamber. In one embodiment two thermocouple wires are configured to double the sensitivity of the probe in one region.

Reliability of High-Temperature Fixed-Point Installations over 8 Years

NASA Astrophysics Data System (ADS)

Elliott, C. J.; Ford, T.; Ongrai, O.; Pearce, J. V.

2017-12-01

At NPL, high-temperature metal-carbon eutectic fixed points have been set up for thermocouple calibration purposes since 2006, for realising reference temperatures above the highest point specified in the International Temperature Scale of 1990 for contact thermometer calibrations. Additionally, cells of the same design have been provided by NPL to other national measurement institutes (NMIs) and calibration laboratories over this period, creating traceable and ISO 17025 accredited facilities around the world for calibrating noble metal thermocouples at 1324 {°}C (Co-C) and 1492 {°}C (Pd-C). This paper shows collections of thermocouple calibration results obtained during use of the high-temperature fixed-point cells at NPL and, as further examples, the use of cells installed at CCPI Europe (UK) and NIMT (Thailand). The lifetime of the cells can now be shown to be in excess of 7 years, whether used on a weekly or monthly basis, and whether used in an NMI or industrial calibration laboratory.

A Thermoelectric Generator Using Porous Si Thermal Isolation

PubMed Central

Hourdakis, Emmanouel; Nassiopoulou, Androula G.

2013-01-01

In this paper we report on a thermoelectric generator (TEG) using thermal isolation provided by a thick porous Si layer locally formed on the Si wafer and thermocouples composed of p-doped polycrystalline Si/Al. The “hot” contacts of the thermocouples lie on the porous Si layer, while the “cold” contacts lie on bulk crystalline Si. A housing was also designed and fabricated in order to transfer any external temperature change on the “hot” contacts of the thermocouples, the “cold” contacts being isolated from the “hot” contacts by a thick resist layer. The fabrication of the sensing element (Si die) is fully compatible with batch Si processing. The output power of the thermoelectric generator depends on the porous Si isolation layer thickness, porosity, structure and morphology. For a mesoporous Si layer of 60% porosity and a macroscopic temperature differential of 10 K, an output power of 0.39 μW/cm2 was measured for a 50 μm thick porous Si layer. PMID:24152923

Evaluation of Piecewise Polynomial Equations for Two Types of Thermocouples

PubMed Central

Chen, Andrew; Chen, Chiachung

2013-01-01

Thermocouples are the most frequently used sensors for temperature measurement because of their wide applicability, long-term stability and high reliability. However, one of the major utilization problems is the linearization of the transfer relation between temperature and output voltage of thermocouples. The linear calibration equation and its modules could be improved by using regression analysis to help solve this problem. In this study, two types of thermocouple and five temperature ranges were selected to evaluate the fitting agreement of different-order polynomial equations. Two quantitative criteria, the average of the absolute error values |e|ave and the standard deviation of calibration equation estd, were used to evaluate the accuracy and precision of these calibrations equations. The optimal order of polynomial equations differed with the temperature range. The accuracy and precision of the calibration equation could be improved significantly with an adequate higher degree polynomial equation. The technique could be applied with hardware modules to serve as an intelligent sensor for temperature measurement. PMID:24351627

The Effect of Grain Size on the Radiation Response of Silicon Carbide and its Dependence on Irradiation Species and Temperature

NASA Astrophysics Data System (ADS)

Jamison, Laura

In recent years the push for green energy sources has intensified, and as part of that effort accident tolerant and more efficient nuclear reactors have been designed. These reactors demand exceptional material performance, as they call for higher temperatures and doses. Silicon carbide (SiC) is a strong candidate material for many of these designs due to its low neutron cross-section, chemical stability, and high temperature resistance. The possibility of improving the radiation resistance of SiC by reducing the grain size (thus increasing the sink density) is explored in this work. In-situ electron irradiation and Kr ion irradiation was utilized to explore the radiation resistance of nanocrystalline SiC (nc-SiC), SiC nanopowders, and microcrystalline SiC. Electron irradiation simplifies the experimental results, as only isolated Frenkel pairs are produced so any observed differences are simply due to point defect interactions with the original microstructure. Kr ion irradiation simulates neutron damage, as large radiation cascades with a high concentration of point defects are produced. Kr irradiation studies found that radiation resistance decreased with particle size reduction and grain refinement (comparing nc-SiC and microcrystalline SiC). This suggests that an interface-dependent amorphization mechanism is active in SiC, suggested to be interstitial starvation. However, under electron irradiation it was found that nc-SiC had improved radiation resistance compared to single crystal SiC. This was found to be due to several factors including increased sink density and strength and the presence of stacking faults. The stacking faults were found to improve radiation response by lowering critical energy barriers. The change in radiation response between the electron and Kr ion irradiations is hypothesized to be due to either the change in ion type (potential change in amorphization mechanism) or a change in temperature (at the higher temperatures of the Kr ion irradiation, critical energy barriers can be overcome without the assistance of stacking faults). The dependence of the radiation response of SiC on grain size is not as straight forward as initially presumed. The stacking faults present in many nc-SiC materials boost radiation resistance, but an increased number of interfaces may lead to a reduction in radiation response.

INTRAPUPAL TEMPERATURE VARIATION DURING ER,CR:YSGG ENAMEL IRRADIATION ON CARIES PREVENTION

PubMed Central

de Freitas, Patrícia Moreira; Soares-Geraldo, Débora; Biella-Silva, Ana Cristina; Silva, Amanda Verna; da Silveira, Bruno Lopes; Eduardo, Carlos de Paula

2008-01-01

Studies have shown the cariostatic effect of Er,Cr:YSGG (2.78 μm) laser irradiation on human enamel and have suggested its use on caries prevention. However there are still no reports on the intrapulpal temperature increase during enamel irradiation using parameters for caries prevention. The aim of this in vitro study was to evaluate the temperature variation in the pulp chamber during human enamel irradiation with Er,Cr:YSGG laser at different energy densities. Fifteen enamel blocks obtained from third molars (3 x 3 x 3 mm) were randomly assigned to 3 groups (n=5): G1 – Er,Cr:YSGG laser 0.25 W, 20 Hz, 2.84 J/cm2, G2 – Er,Cr:YSGG laser 0.50 W, 20 Hz, 5.68 J/cm2, G3 – Er,Cr:YSGG laser 0.75 W, 20 Hz, 8.52 J/cm2. During enamel irradiation, two thermocouples were fixed in the inner surface of the specimens and a thermal conducting paste was used. One-way ANOVA did not show statistically significant difference among the experimental groups (α=0.05). There was intrapulpal temperature variation ≤0.1°C for all irradiation parameters. In conclusion, under the tested conditions, the use of Er,Cr:YSGG laser with parameters set for caries prevention lead to an acceptable temperature increase in the pulp chamber. PMID:19089198

Insulating Behavior in Graphene with Irradiation-induced Lattice Defects

NASA Astrophysics Data System (ADS)

Chen, Jian-Hao; Williams, Ellen; Fuhrer, Michael

2010-03-01

We irradiated cleaned graphene on silicon dioxide in ultra-high vacuum with low energy inert gas ions to produce lattice defects [1], and investigated in detail the transition from metallic to insulating temperature dependence of the conductivity as a function of defect density. We measured the low field magnetoresistance and temperature-dependent resistivity in situ and find that weak localization can only account for a small correction of the resistivity increase with decreasing temperature. We will discuss possible origins of the insulating temperature dependent resistivity in defected graphene in light of our recent experiments. [4pt] [1] Jian-Hao Chen, W. G. Cullen, C. Jang, M. S. Fuhrer, E. D. Williams, PRL 102, 236805 (2009)

Highly uniform resistive switching properties of amorphous InGaZnO thin films prepared by a low temperature photochemical solution deposition method.

PubMed

Hu, Wei; Zou, Lilan; Chen, Xinman; Qin, Ni; Li, Shuwei; Bao, Dinghua

2014-04-09

We report on highly uniform resistive switching properties of amorphous InGaZnO (a-IGZO) thin films. The thin films were fabricated by a low temperature photochemical solution deposition method, a simple process combining chemical solution deposition and ultraviolet (UV) irradiation treatment. The a-IGZO based resistive switching devices exhibit long retention, good endurance, uniform switching voltages, and stable distribution of low and high resistance states. Electrical conduction mechanisms were also discussed on the basis of the current-voltage characteristics and their temperature dependence. The excellent resistive switching properties can be attributed to the reduction of organic- and hydrogen-based elements and the formation of enhanced metal-oxide bonding and metal-hydroxide bonding networks by hydrogen bonding due to UV irradiation, based on Fourier-transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and Field emission scanning electron microscopy analysis of the thin films. This study suggests that a-IGZO thin films have potential applications in resistive random access memory and the low temperature photochemical solution deposition method can find the opportunity for further achieving system on panel applications if the a-IGZO resistive switching cells were integrated with a-IGZO thin film transistors.

Study on structural recovery of graphite irradiated with swift heavy ions at high temperature

NASA Astrophysics Data System (ADS)

Pellemoine, F.; Avilov, M.; Bender, M.; Ewing, R. C.; Fernandes, S.; Lang, M.; Li, W. X.; Mittig, W.; Schein, M.; Severin, D.; Tomut, M.; Trautmann, C.; Zhang, F. X.

2015-12-01

Thin graphite foils bombarded with an intense high-energy (8.6 MeV/u) gold beam reaching fluences up to 1 × 1015 ions/cm2 lead to swelling and electrical resistivity changes. As shown earlier, these effects are diminished with increasing irradiation temperature. The work reported here extends the investigation of beam induced changes of these samples by structural analysis using synchrotron X-ray diffraction and transmission electron microscope. A nearly complete recovery from swelling at irradiation temperatures above about 1500 °C is identified.

Performance Analysis and Optimization of Concentrating Solar Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Lamba, Ravita; Manikandan, S.; Kaushik, S. C.

2018-06-01

A thermodynamic model for a concentrating solar thermoelectric generator considering the Thomson effect combined with Fourier heat conduction, Peltier, and Joule heating has been developed and optimized in MATLAB environment. The temperatures at the hot and cold junctions of the thermoelectric generator were evaluated by solving the energy balance equations at both junctions. The effects of the solar concentration ratio, input electrical current, number of thermocouples, and electrical load resistance ratio on the power output and energy and exergy efficiencies of the system were studied. Optimization studies were carried out for the STEG system, and the optimum number of thermocouples, concentration ratio, and resistance ratio determined. The results showed that the optimum values of these parameters are different for conditions of maximum power output and maximum energy and exergy efficiency. The optimum values of the concentration ratio and load resistance ratio for maximum energy efficiency of 5.85% and maximum exergy efficiency of 6.29% were found to be 180 and 1.3, respectively, with corresponding power output of 4.213 W. Furthermore, at higher concentration ratio (C = 600), the optimum number of thermocouples was found to be 101 for maximum power output of 13.75 W, maximum energy efficiency of 5.73%, and maximum exergy efficiency of 6.16%. Moreover, the optimum number of thermocouple was the same for conditions of maximum power output and energy and exergy efficiency. The results of this study may provide insight for design of actual concentrated solar thermoelectric generator systems.

Development of a Sheathed Miniature Aerothermal Reentry Thermocouple for Thermal Protection System Materials

NASA Technical Reports Server (NTRS)

Martinez, Edward R.; Weber, Carissa Tudryn; Oishi, Tomo; Santos, Jose; Mach, Joseph

2011-01-01

The Sheathed Miniature Aerothermal Reentry Thermocouple is a micro-miniature thermocouple for high temperature measurement in extreme environments. It is available for use in Thermal Protection System materials for ground testing and flight. This paper discusses the heritage, and design of the instrument. Experimental and analytical methods used to verify its performance and limitations are described.

An Automated Thermocouple Calibration System

NASA Technical Reports Server (NTRS)

Bethea, Mark D.; Rosenthal, Bruce N.

1992-01-01

An Automated Thermocouple Calibration System (ATCS) was developed for the unattended calibration of type K thermocouples. This system operates from room temperature to 650 C and has been used for calibration of thermocouples in an eight-zone furnace system which may employ as many as 60 thermocouples simultaneously. It is highly efficient, allowing for the calibration of large numbers of thermocouples in significantly less time than required for manual calibrations. The system consists of a personal computer, a data acquisition/control unit, and a laboratory calibration furnace. The calibration furnace is a microprocessor-controlled multipurpose temperature calibrator with an accuracy of +/- 0.7 C. The accuracy of the calibration furnace is traceable to the National Institute of Standards and Technology (NIST). The computer software is menu-based to give the user flexibility and ease of use. The user needs no programming experience to operate the systems. This system was specifically developed for use in the Microgravity Materials Science Laboratory (MMSL) at the NASA LeRC.

Establishment of the Co-C Eutectic Fixed-Point Cell for Thermocouple Calibrations at NIMT

NASA Astrophysics Data System (ADS)

Ongrai, O.; Elliott, C. J.

2017-08-01

In 2015, NIMT first established a Co-C eutectic temperature reference (fixed-point) cell measurement capability for thermocouple calibration to support the requirements of Thailand's heavy industries and secondary laboratories. The Co-C eutectic fixed-point cell is a facility transferred from NPL, where the design was developed through European and UK national measurement system projects. In this paper, we describe the establishment of a Co-C eutectic fixed-point cell for thermocouple calibration at NIMT. This paper demonstrates achievement of the required furnace uniformity, the Co-C plateau realization and the comparison data between NIMT and NPL Co-C cells by using the same standard Pt/Pd thermocouple, demonstrating traceability. The NIMT measurement capability for noble metal type thermocouples at the new Co-C eutectic fixed point (1324.06°C) is estimated to be within ± 0.60 K (k=2). This meets the needs of Thailand's high-temperature thermocouple users—for which previously there has been no traceable calibration facility.

In Situ Field Measurement of Leaf Water Potential Using Thermocouple Psychrometers 1

PubMed Central

Savage, Michael J.; Wiebe, Herman H.; Cass, Alfred

1983-01-01

Thermocouple psychrometers are the only instruments which can measure the in situ water potential of intact leaves, and which can possibly be used to monitor leaf water potential. Unfortunately, their usefulness is limited by a number of difficulties, among them fluctuating temperatures and temperature gradients within the psychrometer, sealing of the psychrometer chamber to the leaf, shading of the leaf by the psychrometer, and resistance to water vapor diffusion by the cuticle when the stomates are closed. Using Citrus jambhiri, we have tested several psychrometer design and operational modifications and showed that in situ psychrometric measurements compared favorably with simultaneous Scholander pressure chamber measurements on neighboring leaves when the latter were corrected for the osmotic potential. PMID:16663267

Comparing the transient response of a resistive-type sensor with a thin film thermocouple during the post-exposure bake process

NASA Astrophysics Data System (ADS)

Kreider, Kenneth G.; DeWitt, David P.; Fowler, Joel B.; Proctor, James E.; Kimes, William A.; Ripple, Dean C.; Tsai, Benjamin K.

2004-04-01

Recent studies on dynamic temperature profiling and lithographic performance modeling of the post-exposure bake (PEB) process have demonstrated that the rate of heating and cooling may have an important influence on resist lithographic response. Measuring the transient surface temperature during the heating or cooling process with such accuracy can only be assured if the sensors embedded in or attached to the test wafer do not affect the temperature distribution in the bare wafer. In this paper we report on an experimental and analytical study to compare the transient response of embedded platinum resistance thermometer (PRT) sensors with surface-deposited, thin-film thermocouples (TFTC). The TFTCs on silicon wafers have been developed at NIST to measure wafer temperatures in other semiconductor thermal processes. Experiments are performed on a test bed built from a commercial, fab-qualified module with hot and chill plates using wafers that have been instrumented with calibrated type-E (NiCr/CuNi) TFTCs and commercial PRTs. Time constants were determined from an energy-balance analysis fitting the temperature-time derivative to the wafer temperature during the heating and cooling processes. The time constants for instrumented wafers ranged from 4.6 s to 5.1 s on heating for both the TFTC and PRT sensors, with an average difference less than 0.1 s between the TFTCs and PRTs and slightly greater differences on cooling.

A new approach for breeding low-temperature-resistant Volvariella volvacea strains: Genome shuffling in edible fungi.

PubMed

Zhu, Ziping; Wu, Xiao; Lv, Beibei; Wu, Guogan; Wang, Jinbin; Jiang, Wei; Li, Peng; He, Jianhua; Chen, Jianzhong; Chen, Mingjie; Bao, Dapeng; Zhang, Jinsong; Tan, Qi; Tang, Xueming

2016-09-01

Volvariella volvacea is difficult to store fresh because of the lack of low-temperature resistance. Many traditional mutagenic strategies have been applied in order to select out strains resistant to low temperature, but few commercially efficient strains have been produced. In order to break through the bottleneck of traditional breeding and significantly improve low-temperature resistance of the edible fungus V. volvacea, strains resistant to low temperature were constructed by genome shuffling. The optimum conditions of V. volvacea strain mutation, protoplast regeneration, and fusion were determined. After protoplasts were treated with 1% (v/v) ethylmethylsulfonate (EMS), 40 Sec of ultraviolet (UV) irradiation, 600 Gy electron beam implantation, and 750 Gy 60 Co-γ irradiation, separately, the lethality was within 70%-80%, which favored generating protoplasts being used in following forward mutation. Under these conditions, 16 strains of V. volvacea mutated by EMS, electron beam, UV irradiation, and 60 Co-γ irradiation were obtained. The 16 mutated protoplasts were selected to serve as the shuffling pool based on their excellent low-temperature resistance. After four rounds of genome shuffling and low-temperature resistance testing, three strains (VF 1 , VF 2 , and VF 3 ) with high genetic stability were screened. VF 1 , VF 2 , and VF 3 significantly enhanced fruit body shelf life to 20, 28, and 28 H at 10 °C, respectively, which exceeded 25%, 75%, and 75%, respectively, compared with the storage time of V23, the most low-temperature-resistant strain. Genome shuffling greatly improved the low-temperature resistance of V. volvacea, and shortened the course of screening required to generate desirable strains. To our knowledge, this is the first paper to apply genome shuffling to breeding new varieties of mushroom, and offers a new approach for breeding edible fungi with optimized phenotype. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

A comparison of thermocouple and infrared thermographic analysis of temperature rise on the root surface during the continuous wave of condensation technique.

PubMed

Mc Cullagh, J J; Setchell, D J; Gulabivala, K; Hussey, D L; Biagioni, P; Lamey, P J; Bailey, G

2000-07-01

This study was designed to use two methods of temperature measurement to analyse and quantify the in vitro root surface temperature changes during the initial stage of the continuous wave technique of obturation of 17 single-rooted premolar teeth with standard canal preparations. A model was designed to allow simultaneous temperature measurement with both thermocouples and an infrared thermal imaging system. Two thermocouples were placed on the root surface, one coronally and the other near the root apex. A series of thermal images were recorded by an infrared thermal imaging camera during the downpack procedure. The mean temperature rises on the root surface, as measured by the two thermocouples, averaged 13.9 degrees C over the period of study, whilst the infrared thermal imaging system measured an average rise of 28.4 degrees C at the same sites. Temperatures at the more apical point were higher than those measured coronally. After the first wave of condensation, the second activation of the plugger in the canal prior to its removal always resulted in a secondary rise in temperature. The thermal imaging system detected areas of greater temperature change distant from the two selected thermocouple sites. The continuous wave technique of obturation may result in high temperatures on the external root surface. Infrared thermography is a useful device for mapping patterns of temperature change over a large area.

Evaluation of miniature single-wire sheathed thermocouples for turbine blade temperature measurement

NASA Technical Reports Server (NTRS)

Hollanda, R.

1979-01-01

Chromel Alumel thermocouples were used, with sheath diameters of 0.15 and 0.25 mm. Tests were conducted at temperatures ranging from 750 to 1250 K. Both steady state and thermal cycling tests were performed for times up to 200 hours. Initial testing was performed in a low velocity gas stream for long time periods using a Meker-type burner. Additional testing was done in a high velocity gas stream for short time periods using a hot gas tunnel and also in a J75 jet engine. A total of eleven 0.15 mm diameter thermocouples and six 0.25 mm diameter thermocouples were tested. Drift rates up to 2.5% in 10 hours were observed. Photomicrographs show that this design is near the limit of miniaturization based on present manufacturing capabilities. Results indicate that the effects of miniaturization on reliability and accuracy must be considered when choosing thermocouples for a particular application.

Simultaneous measurement of temperature and strain using four connecting wires

NASA Technical Reports Server (NTRS)

Parker, Allen R., Jr.

1993-01-01

This paper describes a new signal-conditioning technique for measuring strain and temperature which uses fewer connecting wires than conventional techniques. Simultaneous measurement of temperature and strain has been achieved by using thermocouple wire to connect strain gages to signal conditioning. This signal conditioning uses a new method for demultiplexing sampled analog signals and the Anderson current loop circuit. Theory is presented along with data to confirm that strain gage resistance change is sensed without appreciable error because of thermoelectric effects. Furthermore, temperature is sensed without appreciable error because of voltage drops caused by strain gage excitation current flowing through the gage resistance.

Prototype thin-film thermocouple/heat-flux sensor for a ceramic-insulated diesel engine

NASA Technical Reports Server (NTRS)

Kim, Walter S.; Barrows, Richard F.

1988-01-01

A platinum versus platinum-13 percent rhodium thin-film thermocouple/heat-flux sensor was devised and tested in the harsh, high-temperature environment of a ceramic-insulated, low-heat-rejection diesel engine. The sensor probe assembly was developed to provide experimental validation of heat transfer and thermal analysis methodologies applicable to the insulated diesel engine concept. The thin-film thermocouple configuration was chosen to approximate an uninterrupted chamber surface and provide a 1-D heat-flux path through the probe body. The engine test was conducted by Purdue University for Integral Technologies, Inc., under a DOE-funded contract managed by NASA Lewis Research Center. The thin-film sensor performed reliably during 6 to 10 hr of repeated engine runs at indicated mean surface temperatures up to 950 K. However, the sensor suffered partial loss of adhesion in the thin-film thermocouple junction area following maximum cyclic temperature excursions to greater than 1150 K.

Effect of diode lasers with wavelength of 445 and 980 nm on a temperature rise when uncovering implants for second stage surgery: An ex-vivo study in pigs.

PubMed

Matys, Jacek; Flieger, Rafał; Dominiak, Marzena

2017-07-01

Many surgical procedures in soft tissue are performed using diode lasers. Recently, a novel diode laser operating at 445 nm wavelength was introduced in dentistry. The aim of our study was to evaluate the time of surgery and an increase in temperature of titanium implants during its uncovering using 445 and 980 nm wavelengths. The research included 45 pig mandibles (n = 45). The specimens were randomly divided into 3 groups (n = 15) according to the laser irradiation mode and wavelength; G1 - 445 nm laser, power: 3 W, continuous wave (CW), distance: 2 mm, power density: 7460 W/cm2, fiber: 320 μm, noncontact mode; G2 - 445 nm laser (power: 2 W, CW, power density: 4970 W/cm2, fiber: 320 μm, contact mode; G3 (control) - 980 nm laser, power: 2.5 W, CW, power density: 15920 W/cm2, fiber: 200 μm, contact mode. The temperature was measured with a 2 K-type thermocouples (a P1 at collar and a P2 at mid height of the implant). The mean temperature rises measured by the P1 thermocouple were 16.9°C, 36.1°C and 21.6°C in the G1, G2 and G3 group, respectively. Significant differences in temperature rise were found between the G1 and G2 group (p = 0.0007) and the G2 and G3 group (p = 0.01). The mean temperature rises measured by the P2 thermocouple were 1.8°C, 1.4°C and 5.6°C in the G1, G2 and G3 group, respectively. Significant differences in temperature rise were found between the G1 and the G2 or G3 group (p = 0.0001). The significant differences among the study groups in average time necessary for uncovering the implants amounted to 69.7, 54.4 and 83.6 s, respectively (p < 0.05). The application of the 445 nm diode laser in non-contact mode reduced the temperature rise of the implants. The additional pulse intervals during laser irradiation with wavelength of 445 nm when operating in contact mode are needed.

Thermal and microstructural effects of nanosecond pulsed Nd:YAG laser irradiation on tooth root surface

NASA Astrophysics Data System (ADS)

Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.; Grill, G.; Liaw, Lih-Huei L.; Berns, Michael W.

1995-05-01

Plaque, calculus and altered cementum removal by scaling and root planing is a fundamental procedure in periodontal treatment. However, the residual smear layer contains cytotoxic and inflammatory mediators which adversely affect healing. Chemical smear layer removal is also problematic. In previous investigations effective smear layer removal was achieved using long pulsed irradiation at 1.06 (mu) . However, laser irradiation was not adequate as an alternative to scaling and root planing procedures and concurrent temperature rises exceeded thermal thresholds for pulpal and periodontal safety. It was the aim of this study to determine whether nanosecond pulsed irradiation at 1.06 (mu) could be used as an alternative or an adjunct to scaling and root planing. Sixty freshly extracted teeth were divided as follows: 5 control, 5 root planed only, 25 irradiated only, 25 root planed and irradiated. Irradiation was performed at fluences of 0.5 - 2.7 J/cm2, total energy densities of 12 - 300 J/cm2, frequencies of 2 - 10 Hz using the Medlite (Continuum) laser. Irradiation-induced thermal events were recorded using a thermocouple within the root canal and a thermal camera to monitor surface temperatures. SEM demonstrated effective smear layer removal with minimal microstructural effects. Surface temperatures increased minimally (< 3 C) at all parameters, intrapulpal temperature rises remained below 4 C at 2 and 5 Hz, F < 0.5 J/cm2. Without prior scaling and root planing, laser effects did not provide an adequately clean root surface.

Surface microstructure and high temperature corrosion resistance of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam

NASA Astrophysics Data System (ADS)

Hao, Shengzhi; Zhao, Limin; He, Dongyun

2013-10-01

The surface microstructure of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam (HCPEB) with long pulse duration of 200 μs was characterized by using optical microscopy, scanning electron microscopy and X-ray diffractometry. The distribution of chemical composition in modified surface layer was measured with electron probe micro-analyzer. The high temperature corrosion resistance of FeCrAl coating was tested in a saturated Na2SO4 and K2SO4 solution at 650 °C. After HCPEB irradiation, the coarse surface of arc-sprayed coating was changed as discrete bulged nodules with smooth and compact appearance. When using low energy density of 20 J/cm2, the surface modified layer was continuous entirely with an average melting depth of ˜30 μm. In the surface remelted layer, Fe and Cr elements gave a uniform distribution, while Al and O elements agglomerated particularly at the concave part between nodule structures to form α-Al2O3 phase. After high temperature corrosion tests, the FeCrAl coating treated with HCPEB of 20 J/cm2 remained a glossy surface with weight increment of ˜51 mg/cm2, decreased by 20% as compared to the initial sample. With the increasing energy density of HCPEB irradiation, the integrity of surface modified layer got segmented due to the formation of larger bulged nodules and cracks at the concave parts. For the HCPEB irradiation of 40 J/cm2, the high temperature corrosion resistance of FeCrAl coating was deteriorated drastically.

Seebeck Changes Due to Residual Cold-Work and Reversible Effects in Type K Bare-Wire Thermocouples

NASA Astrophysics Data System (ADS)

Webster, E. S.

2017-09-01

Type K thermocouples are the most commonly used thermocouple for industrial measurements because of their low cost, wide temperature range, and durability. As with all base-metal thermocouples, Type K is made to match a mathematical temperature-to-emf relationship and not a prescribed alloy formulation. Because different manufacturers use varying alloy formulations and manufacturing techniques, different Type K thermocouples exhibit a range of drift and hysteresis characteristics, largely due to ordering effects in the positive (K+) thermoelement. In this study, these effects are assessed in detail for temperatures below 700°C in the Type K wires from nine manufacturers. A linear gradient furnace and a high-resolution homogeneity scanner combined with the judicious use of annealing processes allow measurements that separately identify the effects of cold-work, ordering, and oxidation to be made. The results show most K+ alloys develop significant errors, but the magnitudes of the contributions of each process vary substantially between the different K+ wires. In practical applications, the measurement uncertainties achievable with Type K therefore depend not only on the wire formulation but also on the temperature, period of exposure, and, most importantly, the thermal treatments prior to use.

Grain Size Threshold for Enhanced Irradiation Resistance in Nanocrystalline and Ultrafine Tungsten

DOE PAGES

El Atwani, Osman; Hinks, Jonathan; Greaves, Graeme; ...

2017-02-21

Nanocrystalline metals are considered highly radiation-resistant materials due to their large grain boundary areas. Here, the existence of a grain size threshold for enhanced irradiation resistance in high-temperature helium-irradiated nanocrystalline and ultrafine tungsten is demonstrated. Average bubble density, projected bubble area and the corresponding change in volume were measured via transmission electron microscopy and plotted as a function of grain size for two ion fluences. Nanocrystalline grains of less than 35 nm size possess ~10–20 times lower change in volume than ultrafine grains and this is discussed in terms of the grain boundaries defect sink efficiency.

A joint computational and experimental study to evaluate Inconel-sheathed thermocouple performance in flames.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brundage, Aaron L.; Nicolette, Vernon F.; Donaldson, A. Burl

2005-09-01

A joint experimental and computational study was performed to evaluate the capability of the Sandia Fire Code VULCAN to predict thermocouple response temperature. Thermocouple temperatures recorded by an Inconel-sheathed thermocouple inserted into a near-adiabatic flat flame were predicted by companion VULCAN simulations. The predicted thermocouple temperatures were within 6% of the measured values, with the error primarily attributable to uncertainty in Inconel 600 emissivity and axial conduction losses along the length of the thermocouple assembly. Hence, it is recommended that future thermocouple models (for Inconel-sheathed designs) include a correction for axial conduction. Given the remarkable agreement between experiment and simulation,more » it is recommended that the analysis be repeated for thermocouples in flames with pollutants such as soot.« less

Performance evaluation of an infrared thermocouple.

PubMed

Chen, Chiachung; Weng, Yu-Kai; Shen, Te-Ching

2010-01-01

The measurement of the leaf temperature of forests or agricultural plants is an important technique for the monitoring of the physiological state of crops. The infrared thermometer is a convenient device due to its fast response and nondestructive measurement technique. Nowadays, a novel infrared thermocouple, developed with the same measurement principle of the infrared thermometer but using a different detector, has been commercialized for non-contact temperature measurement. The performances of two-kinds of infrared thermocouples were evaluated in this study. The standard temperature was maintained by a temperature calibrator and a special black cavity device. The results indicated that both types of infrared thermocouples had good precision. The error distribution ranged from -1.8 °C to 18 °C as the reading values served as the true values. Within the range from 13 °C to 37 °C, the adequate calibration equations were the high-order polynomial equations. Within the narrower range from 20 °C to 35 °C, the adequate equation was a linear equation for one sensor and a two-order polynomial equation for the other sensor. The accuracy of the two kinds of infrared thermocouple was improved by nearly 0.4 °C with the calibration equations. These devices could serve as mobile monitoring tools for in situ and real time routine estimation of leaf temperatures.

46 CFR 164.008-5 - Test report.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., including initial temperature, for each thermocouple together with curves of average temperature for the unexposed surface of the insulation and the thermocouple recording the highest temperature. In addition, for... each furnace and each surface of insulation thermocouple together with the initial temperature of each...

46 CFR 164.008-5 - Test report.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., including initial temperature, for each thermocouple together with curves of average temperature for the unexposed surface of the insulation and the thermocouple recording the highest temperature. In addition, for... each furnace and each surface of insulation thermocouple together with the initial temperature of each...

Threaded average temperature thermocouple

NASA Technical Reports Server (NTRS)

Ward, Stanley W. (Inventor)

1990-01-01

A threaded average temperature thermocouple 11 is provided to measure the average temperature of a test situs of a test material 30. A ceramic insulator rod 15 with two parallel holes 17 and 18 through the length thereof is securely fitted in a cylinder 16, which is bored along the longitudinal axis of symmetry of threaded bolt 12. Threaded bolt 12 is composed of material having thermal properties similar to those of test material 30. Leads of a thermocouple wire 20 leading from a remotely situated temperature sensing device 35 are each fed through one of the holes 17 or 18, secured at head end 13 of ceramic insulator rod 15, and exit at tip end 14. Each lead of thermocouple wire 20 is bent into and secured in an opposite radial groove 25 in tip end 14 of threaded bolt 12. Resulting threaded average temperature thermocouple 11 is ready to be inserted into cylindrical receptacle 32. The tip end 14 of the threaded average temperature thermocouple 11 is in intimate contact with receptacle 32. A jam nut 36 secures the threaded average temperature thermocouple 11 to test material 30.

Thermocouple Errors when Mounted on Cylindrical Surfaces in Abnormal Thermal Environments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakos, James T.; Suo-Anttila, Jill M.; Zepper, Ethan T.

Mineral-insulated, metal-sheathed, Type-K thermocouples are used to measure the temperature of various items in high-temperature environments, often exceeding 1000degC (1273 K). The thermocouple wires (chromel and alumel) are protected from the harsh environments by an Inconel sheath and magnesium oxide (MgO) insulation. The sheath and insulation are required for reliable measurements. Due to the sheath and MgO insulation, the temperature registered by the thermocouple is not the temperature of the surface of interest. In some cases, the error incurred is large enough to be of concern because these data are used for model validation, and thus the uncertainties of themore » data need to be well documented. This report documents the error using 0.062" and 0.040" diameter Inconel sheathed, Type-K thermocouples mounted on cylindrical surfaces (inside of a shroud, outside and inside of a mock test unit). After an initial transient, the thermocouple bias errors typically range only about +-1-2% of the reading in K. After all of the uncertainty sources have been included, the total uncertainty to 95% confidence, for shroud or test unit TCs in abnormal thermal environments, is about +-2% of the reading in K, lower than the +-3% typically used for flat shrouds. Recommendations are provided in Section 6 to facilitate interpretation and use of the results. .« less

A Highly Thermostable In₂O₃/ITO Thin Film Thermocouple Prepared via Screen Printing for High Temperature Measurements.

PubMed

Liu, Yantao; Ren, Wei; Shi, Peng; Liu, Dan; Zhang, Yijun; Liu, Ming; Ye, Zuo-Guang; Jing, Weixuan; Tian, Bian; Jiang, Zhuangde

2018-03-23

An In₂O₃/ITO thin film thermocouple was prepared via screen printing. Glass additives were added to improve the sintering process and to increase the density of the In₂O₃/ITO films. The surface and cross-sectional images indicate that both the grain size and densification of the ITO and In₂O₃ films increased with the increase in annealing time. The thermoelectric voltage of the In₂O₃/ITO thermocouple was 53.5 mV at 1270 °C at the hot junction. The average Seebeck coefficient of the thermocouple was calculated as 44.5 μV/°C. The drift rate of the In₂O₃/ITO thermocouple was 5.44 °C/h at a measuring time of 10 h at 1270 °C.

Measurement of pulp temperature increase to externally applied heat (argon laser, hot water, drilling).

PubMed

Renneboog-Squilbin, C; Nammour, S; Coomans, D; Barel, A; Carleer, M; Dourov, N

1989-09-01

In order to weld cracks in tooth enamel, it is necessary to bring the surface of the tooth to the fusion temperature of the enamel (greater than 1,000 degrees C). The study investigated whether this increase in surface temperature can cause damage to the vitality of the tooth by recording, using a thermocouple, the temperature in the pulp chamber of teeth exposed to argon laser irradiation (power density after focusing: 4000 W/cm2; duration of continuous irradiation: 1-5 seconds). These pulp temperature increases were compared with those considered safe for the tooth, i.e., contact with a hot drink, drilling of cavities with air + water cooling. It was shown that punctual irradiations with an argon laser for periods of 2 or 4 seconds generated temperature increases in the pulp chamber which were less than inferior to those caused by contact with water at 54-55 degrees C for 1 or 2 seconds, and were of the same order as those caused by the drilling of class III or V cavities of 1 mm in depth and 1 mm in diameter. These results suggest that it is worth continuing research into applying the technique in the mouth.

Temperature measurement reliability and validity with thermocouple extension leads or changing lead temperature.

PubMed

Jutte, Lisa S; Long, Blaine C; Knight, Kenneth L

2010-01-01

Thermocouples' leads are often too short, necessitating the use of an extension lead. To determine if temperature measures were influenced by extension-lead use or lead temperature changes. Descriptive laboratory study. Laboratory. Experiment 1: 10 IT-21 thermocouples and 5 extension leads. Experiment 2: 5 IT-21 and PT-6 thermocouples. In experiment 1, temperature data were collected on 10 IT-21 thermocouples in a stable water bath with and without extension leads. In experiment 2, temperature data were collected on 5 IT-21 and PT-6 thermocouples in a stable water bath before, during, and after ice-pack application to extension leads. In experiment 1, extension leads did not influence IT-21 validity (P  =  .45) or reliability (P  =  .10). In experiment 2, postapplication IT-21 temperatures were greater than preapplication and application measures (P < .05). Extension leads had no influence on temperature measures. Ice application to leads may increase measurement error.

Gold ink coating of thermocouple sheaths

DOEpatents

Ruhl, H. Kenneth

1992-01-01

A method is provided for applying a gold ink coating to a thermocouple sheath which includes the steps of electropolishing and oxidizing the surface of the thermocouple sheath, then dipping the sheath into liquid gold ink, and finally heat curing the coating. The gold coating applied in this manner is highly reflective and does not degrade when used for an extended period of time in an environment having a temperature over 1000.degree. F. Depending on the application, a portion of the gold coating covering the tip of the thermocouple sheath is removed by abrasion.

Fabrication and Characterization of Miniaturized Thermocouples

NASA Astrophysics Data System (ADS)

Munzel, Marco; Peinke, Joachim; Kittel, Achim

2002-11-01

The measurement of thermal fluctuations is important for discovering transport features of a passive scalar in fluids. We present a thermal sensor based on a miniaturized thermocouple. Its coaxial setup results from the fabrication as a micropipette normally used in neurobiology. The glass micropipettes contain a core of gold, antimony, or resistance wire and are coated with platinum. The core material is inserted as molten metal or wire and thinned during the fabrication process. The achieved tip diameters are 1μm and less which enhance the spatial and temporal resolution significantly. Because of its chemically inert coating, these sensors are applicative for detecting temperature fluctuations in large variety of liquids and gases. In addition, such thermocouples are intrinsically suitable for applications in scanning probe microscopy. The characterization of these sensors and first results from turbulent free-jet measurements are presented.

All-optical technique for measuring thermal properties of materials at static high pressure

NASA Astrophysics Data System (ADS)

Pangilinan, G. I.; Ladouceur, H. D.; Russell, T. P.

2000-10-01

The development and implementation of an all-optical technique for measuring thermal transport properties of materials at high pressure in a gem anvil cell are reported. Thermal transport properties are determined by propagating a thermal wave in a material subjected to high pressures, and measuring the temperature as a function of time using an optical sensor embedded downstream in the material. Optical beams are used to deposit energy and to measure the sensor temperature and replace the resistive heat source and the thermocouples of previous methods. This overcomes the problems introduced with pressure-induced resistance changes and the spatial limitations inherent in previous high-pressure experimentation. Consistent with the heat conduction equation, the material's specific heat, thermal conductivity, and thermal diffusivity (κ) determine the sensor's temperature rise and its temporal profile. The all-optical technique described focuses on room-temperature thermal properties but can easily be applied to a wide temperature range (77-600 K). Measurements of thermal transport properties at pressure up to 2.0 GPa are reported, although extension to much higher pressures are feasible. The thermal properties of NaCl, a commonly used material for high-pressure experiments are measured and shown to be consistent with those obtained using the traditional methods.

The effects of cooling systems on CO2-lased human enamel.

PubMed

Lian, H J; Lan, W H; Lin, C P

1996-12-01

The thermal effects on dentin during CO2 laser irradiation on human enamel were investigated. To simulate the clinical practice, two cooling methods (air and water spray) were applied immediately after laser exposure, whereas one group without cooling was served as control. Three hundred and sixty uniform tooth blocks were obtained from freshly extracted human third molars. Temperature change measurements were made via electrical thermocouple implanted within the tooth block 2 mm away from the enamel surface. Experimental treatments consisted of lasing without cooling, lasing with 0.5-ml/sec water cooling, and lasing with 15-psi air cooling. Our results indicated that (1) both air- and water-cooling groups could reduce temperature elevation significantly; (2) the larger power energy resulted in the higher temperature elevation. In conclusion, for CO2 laser irradiation on human enamel both water- and air-cooling methods may be effective on prevention of thermal damage of pulp.

Irradiation effects on thermal properties of LWR hydride fuel

NASA Astrophysics Data System (ADS)

Terrani, Kurt; Balooch, Mehdi; Carpenter, David; Kohse, Gordon; Keiser, Dennis; Meyer, Mitchell; Olander, Donald

2017-04-01

Three hydride mini-fuel rods were fabricated and irradiated at the MIT nuclear reactor with a maximum burnup of 0.31% FIMA or ∼5 MWd/kgU equivalent oxide fuel burnup. Fuel rods consisted of uranium-zirconium hydride (U (30 wt%)ZrH1.6) pellets clad inside a LWR Zircaloy-2 tubing. The gap between the fuel and the cladding was filled with lead-bismuth eutectic alloy to eliminate the gas gap and the large temperature drop across it. Each mini-fuel rod was instrumented with two thermocouples with tips that are axially located halfway through the fuel centerline and cladding surface. In-pile temperature measurements enabled calculation of thermal conductivity in this fuel as a function of temperature and burnup. In-pile thermal conductivity at the beginning of test agreed well with out-of-pile measurements on unirradiated fuel and decreased rapidly with burnup.

Temperature measurement of burning aluminum powder based on the double line method of atomic emission spectra

NASA Astrophysics Data System (ADS)

Tang, Huijuan; Hao, Xiaojian; Hu, Xiaotao

2018-01-01

In the case of conventional contact temperature measurement, there is a delay phenomenon and high temperature resistant materials limitation. By using the faster response speed and theoretically no upper limit of the non-contact temperature method, the measurement system based on the principle of double line atomic emission spectroscopy temperature measurement is put forward, the structure and theory of temperature measuring device are introduced. According to the atomic spectrum database (ASD), Aluminum(Al) I 690.6 nm and Al I 708.5 nm are selected as the two lines in the temperature measurement. The intensity ratio of the two emission lines was measured by a spectrometer to obtain the temperature of Al burning in pure oxygen, and the result compared to the temperature measured by the thermocouple. It turns out that the temperature correlation between the two methods is good, and it proves the feasibility of the method.

Electrical Resistivity Measurement of Cu and Zn on the Pressure-Dependent Melting Boundary

NASA Astrophysics Data System (ADS)

Secco, R. A.; Ezenwa, I.; Yong, W.

2016-12-01

Understanding how the core cools through heat conduction and modelling the geodynamo requires knowledge of the thermal and electrical conductivity of solid and liquid Fe and its relevant alloys at high pressures. It has been proposed that electrical resistivity of a pure metal is constant along its P-dependent melting boundary (Stacey and Anderson, PEPI, 2001). If confirmed, this invariant behavior could serve as a practical tool for low P studies to assess electrical resistivity of Earth's core. Since Earth's inner core boundary (ICB) is a melting boundary of mainly Fe, measurements of electrical resistivity of Fe at the melting boundary, under any P, would serve as a proxy for the resistivity at the ICB. A revised treatment (Stacey and Loper, PEPI, 2007) accounted for s-d scattering in transition metals with unfilled d-bands and limited the proposal to metals with electrons of the same type in filled d-band metals. To test this proposal, we made high P, T measurements of electrical resistivity of d-band filled Cu and Zn in solid and liquid states. Experiments were carried out in a 1000 ton cubic anvil press up to 5 GPa and 300K above melting temperatures. Two thermocouples placed at opposite ends of the wire sample served as T probes as well as 4-wire resistance electrodes in a switched circuit. A polarity switch was used to remove any bias voltage measurement using thermocouple legs. Electron microprobe analyses were used to check the compositions of the recovered samples. The expected resistivity decrease with P and increase with T were found and comparisons with 1atm data are in very good agreement. Within the error of measurement, the resistivity values of Cu decrease along the melting boundary while Zn appears to support the hypothesis of constant resistivity along the melting boundary.

An integrated photo-thermal sensing system for rapid and direct diagnosis of anemia.

PubMed

Kwak, Bong Seop; Kim, Hyung Joon; Kim, Hyun Ok; Jung, Hyo-Il

2010-12-15

This article presents a thermal biosensor to diagnose the anemia without chemical treatments using temperature increase of red blood cells (RBC) when hemoglobin molecules absorb specific wavelength of photons and convert them to thermal energy. For measuring temperature change of red blood cell, the micro-scaled platinum resistance temperature detector (Pt RTD) was developed. For maintenance of constant ambient temperature, we designed and fabricated a thermostat system. The thermostat system consists of a K-type thermocouple and two electric heaters that serve to increase the system temperature, which is monitored by the thermocouple. Both heaters and the thermocouple were connected to a proportional-integral-derivative (PID) controller and enabled to maintain the temperature constant (<±0.1°C). For specific heating of red blood cell, 8.0 W/cm(2) diode pumped solid state (DPSS) continuous wave (CW) laser module was used with 532 nm wavelength. Using this system, we successfully measured the temperature variations (from 66.33±2.72°C to 74.16±2.06°C) of whole blood samples from 10 anemic patients and subsequently determined the concentration of hemoglobin (from 7.2 g/dL to 9.8 g/dL). The method proposed in this paper requires significantly less amount of whole blood sample (6 μl) compared with the conventional methods (175 μl) and allows instantaneous diagnosis (3 s) of anemia. Copyright © 2010 Elsevier B.V. All rights reserved.

Mounting a thermocouple of type E onto a Cu single crystal for use in a magnetically sensitive environment below 77 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potzuweit, Alexander; Schaffner, Anuschka; Jänsch, Heinz Julius, E-mail: heinz.jaensch@physik.uni-marburg.de

2014-09-01

Type E thermocouples show magnetic effects at liquid nitrogen temperature and below. This may cause trouble in experiments that are sensitive to magnetic stray fields like nuclear magnetic resonance, photoemission or high resolution electron energy loss spectroscopy. Here, a solution for the temperature measurement of a single crystal is presented. The authors weld a copper rod onto the back side of the single crystal, thereby relocating the sensitive sample from the thermocouple attachment position. They show that it is possible to measure the crystal temperature at the end of the rod while significantly reducing the ferromagnetic influence due to themore » increased distance.« less

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level.

PubMed

Vines, L; Bhoodoo, C; von Wenckstern, H; Grundmann, M

2017-12-13

The evolution of sheet resistance of n-type In 2 O 3 and Ga 2 O 3 exposed to bombardment with MeV 12 C and 28 Si ions at 35 K is studied in situ. While the sheet resistance of Ga 2 O 3 increased by more than eight orders of magnitude as a result of ion irradiation, In 2 O 3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga 2 O 3 remained highly resistive, while In 2 O 3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to [Formula: see text] cm -2 . A model where larger defect complexes preferentially produce donor like defects in In 2 O 3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level

NASA Astrophysics Data System (ADS)

Vines, L.; Bhoodoo, C.; von Wenckstern, H.; Grundmann, M.

2018-01-01

The evolution of sheet resistance of n-type In2O3 and Ga2O3 exposed to bombardment with MeV 12C and 28Si ions at 35 K is studied in situ. While the sheet resistance of Ga2O3 increased by more than eight orders of magnitude as a result of ion irradiation, In2O3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga2O3 remained highly resistive, while In2O3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to 2 × 1012 cm-2. A model where larger defect complexes preferentially produce donor like defects in In2O3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

High-Temperature Properties of Mold Flux Observed and Measured In Situ by Single/Double Hot-Thermocouple Technique

NASA Astrophysics Data System (ADS)

Wang, Wanlin; Lyu, Peisheng; Zhou, Lejun; Li, Huan; Zhang, Tongsheng

2018-05-01

Mold flux plays very important roles in the continuous casting process, and its high-temperature properties affect the quality of the final as-cast product greatly. Investigations on the melting, isothermal and nonisothermal crystallization, and phase evolution behaviors under a simulated temperature field for the mold flux system using the single/double hot-thermocouple technique (S/DHTT) were reviewed. Meanwhile, further in situ observations on the wetting behavior and heat transfer ability of the mold flux system were also carried out using the S/DHTT. The results summarized here provide a clear understanding of both the high-temperature properties of mold flux and the detailed application of advanced real-time visual high-temperature S/DHTT to this molten slag system.

Thermocouple Extension-Wire-Connections and Low Temperatures

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Mitchell, Mark; Richardson, Gregory

2000-01-01

Experiments were carried out to determine the casue of erroneous readings from thermocouples of type K when measuring temperatures of liquid hydrogen. It was believed to be linked to te temperature of the connector used to extend the thermocouple wires to the voltage meter.

Measuring Subsurface Water Fluxes Using a Heat Pulse Sensor

NASA Astrophysics Data System (ADS)

Ochsner, T. E.; Wang, Q.; Horton, R.

2001-12-01

Subsurface water flux is an important parameter in studies of runoff, infiltration, groundwater recharge, and subsurface chemical transport. Heat pulse sensors have been proposed as promising tools for measuring subsurface water fluxes. Our heat pulse probe consists of three 4-cm stainless-steel needles embedded in a waterproof epoxy body. The needles contain resistance heaters and thermocouples. The probes are connected to an external datalogger and power supply and then installed in soil. To measure the water flux, a 15-s heat pulse is generated at the middle needle using the power supply and the resistance heater, and the temperature increases at the needles 6-mm upstream and downstream from the heater are recorded using the thermocouples and datalogger. To date, heat pulse methods have required cumbersome mathematical analysis to calculate soil water flux from this measured data. We present a new mathematical analysis showing that a simple relationship exists between water flux and the ratio of the temperature increase downstream from the line heat source to the temperature increase upstream from the line heat source. The simplicity of this relationship makes heat pulse sensors a more attractive option for measuring subsurface water fluxes.

Measurement of respiratory rate and timing using a nasal thermocouple.

PubMed

Marks, M K; South, M; Carter, B G

1995-05-01

The aims of this study were to assess aspects of the response of a small thermocouple to temperature change, and to evaluate whether such a thermocouple could be used intermittently to measure respiratory rate and timing by detecting the changes in nasal temperature occurring with breathing. The study had three parts. First, three similar, fast-responding thermocouples were immersed repeatedly in warm water. Second, the influence of atmospheric temperature on the signal of a thermocouple placed at different sites within the nasal orifice was studied. The signals produced were continuously displayed and analyzed using a laptop computer to allow evaluation of the thermocouples' response characteristics. Third, simultaneous respiratory recordings were acquired using a nasal thermocouple and a nasal pneumotachograph in 12 teenaged subjects. The respiratory rate and the periods of time taken for inspiration (Ti) and expiration (Te) were calculated and compared. The thermocouples' responses to the temperature changes associated with breathing and immersion into water were rapid and consistent. The rate of the signals' decay, following the peak signal marking expiration, was influenced by the atmospheric temperature. The time constants of the thermocouples were similar (mean time constant = 0.41 sec, standard deviation (SD) = 0.07). Optimal respiratory recordings were obtained, with least discomfort, when the thermocouple was positioned at 0 to 4 mm within the nasal orifice. In comparing the respiratory recordings acquired simultaneously with a thermocouple and pneumotachograph, the respiratory rates were identical, and the Ti and Te values were similar (mean difference 0.04 sec (95% CI: -0.11 to 0.21 sec) and -0.04 sec (95% CI: -0.20 to 0.12 sec), respectively). Intermittent measurements of respiratory rate and timing using a nasal thermocouple accurately reflected measurements obtained from nasal airflow using a pneumotachograph.

Performance Evaluation of an Infrared Thermocouple

PubMed Central

Chen, Chiachung; Weng, Yu-Kai; Shen, Te-Ching

2010-01-01

The measurement of the leaf temperature of forests or agricultural plants is an important technique for the monitoring of the physiological state of crops. The infrared thermometer is a convenient device due to its fast response and nondestructive measurement technique. Nowadays, a novel infrared thermocouple, developed with the same measurement principle of the infrared thermometer but using a different detector, has been commercialized for non-contact temperature measurement. The performances of two-kinds of infrared thermocouples were evaluated in this study. The standard temperature was maintained by a temperature calibrator and a special black cavity device. The results indicated that both types of infrared thermocouples had good precision. The error distribution ranged from −1.8 °C to 18 °C as the reading values served as the true values. Within the range from 13 °C to 37 °C, the adequate calibration equations were the high-order polynomial equations. Within the narrower range from 20 °C to 35 °C, the adequate equation was a linear equation for one sensor and a two-order polynomial equation for the other sensor. The accuracy of the two kinds of infrared thermocouple was improved by nearly 0.4 °C with the calibration equations. These devices could serve as mobile monitoring tools for in situ and real time routine estimation of leaf temperatures. PMID:22163458

An extremely simple thermocouple made of a single layer of metal.

PubMed

Liu, Haixiao; Sun, Weiqiang; Xu, Shengyong

2012-06-26

A novel temperature sensor consisting of a single layer of metal (Ni, Pd, W, or Pt) is constructed. Its configuration challenges a long-established concept and may lead to development of a new category of devices. Reliable two-dimensional mapping of local temperatures is demonstrated using an array of these sensors. These single-metal thermocouples (SMTCs) can be readily applied on flexible substrates or at high temperatures. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature dependence of the radiation tolerance of nanocrystalline pyrochlores A 2Ti 2O 7 (A = Gd, Ho and Lu)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, J.; Sun, C.; Dholabhai, P. P.

A potentially enhanced radiation resistance of nanocrystalline materials, as a consequence of the high density of interfaces and surfaces, has attracted much attention both to understand the fundamental role of these defect sinks and to develop them for high-radiation environments. Here, irradiation response of nanocrystalline A 2Ti 2O 7 (A = Gd, Ho and Lu) pyrochlore powders with grain sizes of 20–30 nm was investigated by 1-MeV Kr 2+ ion bombardment. In situ transmission electron microscopy (TEM) revealed that the critical amorphization fluence for each nanocrystalline compound at room temperature was greater than that for their coarse-grained counterparts, indicating anmore » enhanced amorphization resistance. The effect of temperature on the irradiation response of one of these compounds, nanocrystalline Lu 2Ti 2O 7, was further examined by performing ion irradiation at an elevated temperature range of 480–600 K. The critical amorphization temperature (T c) was found to be noticeably higher in nanocrystalline Lu 2Ti 2O 7 (610 K) than its coarse-grained counterpart (480 K), revealing that nanocrystalline Lu 2Ti 2O 7 is less resistant to amorphization compared to its coarse-grained phase under high temperatures. We interpret these results with the aid of atomistic simulations. Molecular statics calculations find that cation antisite defects are less energetically costly to form near surfaces than in the bulk, suggesting that the nanocrystalline form of these materials is generally less susceptible to amorphization than coarse-grained counterparts at low temperatures where defect kinetics are negligible. In contrast, at high temperatures, the annealing efficiency of antisite defects by cation interstitials is significantly reduced due to the sink properties of the surfaces in the nanocrystalline pyrochlore, which contributes to the observed higher amorphization temperature in the nano-grained phase than in coarse-grained counterpart. Altogether, these results provide new insight into the behavior of nanocrystalline materials under irradiation.« less

Temperature dependence of the radiation tolerance of nanocrystalline pyrochlores A 2Ti 2O 7 (A = Gd, Ho and Lu)

DOE PAGES

Wen, J.; Sun, C.; Dholabhai, P. P.; ...

2016-03-21

A potentially enhanced radiation resistance of nanocrystalline materials, as a consequence of the high density of interfaces and surfaces, has attracted much attention both to understand the fundamental role of these defect sinks and to develop them for high-radiation environments. Here, irradiation response of nanocrystalline A 2Ti 2O 7 (A = Gd, Ho and Lu) pyrochlore powders with grain sizes of 20–30 nm was investigated by 1-MeV Kr 2+ ion bombardment. In situ transmission electron microscopy (TEM) revealed that the critical amorphization fluence for each nanocrystalline compound at room temperature was greater than that for their coarse-grained counterparts, indicating anmore » enhanced amorphization resistance. The effect of temperature on the irradiation response of one of these compounds, nanocrystalline Lu 2Ti 2O 7, was further examined by performing ion irradiation at an elevated temperature range of 480–600 K. The critical amorphization temperature (T c) was found to be noticeably higher in nanocrystalline Lu 2Ti 2O 7 (610 K) than its coarse-grained counterpart (480 K), revealing that nanocrystalline Lu 2Ti 2O 7 is less resistant to amorphization compared to its coarse-grained phase under high temperatures. We interpret these results with the aid of atomistic simulations. Molecular statics calculations find that cation antisite defects are less energetically costly to form near surfaces than in the bulk, suggesting that the nanocrystalline form of these materials is generally less susceptible to amorphization than coarse-grained counterparts at low temperatures where defect kinetics are negligible. In contrast, at high temperatures, the annealing efficiency of antisite defects by cation interstitials is significantly reduced due to the sink properties of the surfaces in the nanocrystalline pyrochlore, which contributes to the observed higher amorphization temperature in the nano-grained phase than in coarse-grained counterpart. Altogether, these results provide new insight into the behavior of nanocrystalline materials under irradiation.« less

Temperature rise induced by some light emitting diode and quartz-tungsten-halogen curing units.

PubMed

Asmussen, Erik; Peutzfeldt, Anne

2005-02-01

Because of the risk of thermal damage to the pulp, the temperature rise induced by light-curing units should not be too high. LED (light emitting diode) curing units have the main part of their irradiation in the blue range and have been reported to generate less heat than QTH (quartz-tungsten-halogen) curing units. This study had two aims: first, to measure the temperature rise induced by ten LED and three QTH curing units; and, second, to relate the measured temperature rise to the power density of the curing units. The light-induced temperature rise was measured by means of a thermocouple embedded in a small cylinder of resin composite. The power density was measured by using a dental radiometer. For LED units, the temperature rise increased with increasing power density, in a statistically significant manner. Two of the three QTH curing units investigated resulted in a higher temperature rise than LED curing units of the same power density. Previous findings, that LED curing units induce less temperature rise than QTH units, does not hold true in general.

Thermal Recovery from Cold-Working in Type K Bare-Wire Thermocouples

NASA Astrophysics Data System (ADS)

Greenen, A. D.; Webster, E. S.

2017-12-01

Cold-working of most thermocouples has a significant, direct impact on the Seebeck coefficient which can lead to regions of thermoelectric inhomogeneity and accelerated drift. Cold-working can occur during the wire swaging process, when winding the wire onto a bobbin, or during handling by the end user—either accidentally or deliberately. Swaging-induced cold-work in thermocouples, if uniformly applied, may result in a high level of homogeneity. However, on exposure to elevated temperatures, the subsequent recovery process from the cold-working can then result in significant drift, and this can in turn lead to erroneous temperature measurements, often in excess of the specified manufacturer tolerances. Several studies have investigated the effects of cold-work in Type K thermocouples usually by bending, or swaging. However, the amount of cold-work applied to the thermocouple is often difficult to quantify, as the mechanisms for applying the strains are typically nonlinear when applied in this fashion. A repeatable level of cold-working is applied to the different wires using a tensional loading apparatus to apply a known yield displacement to the thermoelements. The effects of thermal recovery from cold-working can then be accurately quantified as a function of temperature, using a linear gradient furnace and a high-resolution homogeneity scanner. Variation in these effects due to differing alloy compositions in Type K wire is also explored, which is obtained by sourcing wire from a selection of manufacturers. The information gathered in this way will inform users of Type K thermocouples about the potential consequences of varying levels of cold-working and its impact on the Seebeck coefficient at a range of temperatures between ˜ 70°C and 600° C. This study will also guide users on the temperatures required to rapidly alleviate the effects of cold-working using thermal annealing treatments.

Response of thermocouples interfaced to electrothermometers when immersed in 5 water bath temperatures.

PubMed

Long, Blaine C; Jutte, Lisa S; Knight, Kenneth L

2010-01-01

Thermocouples and electrothermometers are used in therapeutic modality research. Until recently, researchers assumed that these instruments were valid and reliable. To examine 3 different thermocouple types in 5 degrees C, 15 degrees C, 18.4 degrees C, 25 degrees C, and 35 degrees C water baths. Randomized controlled trial. Therapeutic modality laboratory. Eighteen thermocouple leads were inserted through the wall of a foamed polystyrene cooler. The cooler was filled with water. Six thermocouples (2 of each model) were plugged into the 6 channels of the Datalogger and 6 randomly selected channels in the 2 Iso-Thermexes. A mercury thermometer was immersed into the water and was read every 10 seconds for 4 minutes during each of 6 trials. The entire process was repeated for each of 5 water bath temperatures (5 degrees C, 15 degrees C, 18.4 degrees C, 25 degrees C, 35 degrees C). Temperature and absolute temperature differences among 3 thermocouple types (IT-21, IT-18, PT-6) and 3 electrothermometers (Datalogger, Iso-Thermex calibrated from -50 degrees C to 50 degrees C, Iso-Thermex calibrated from -20 degrees C to 80 degrees C). Validity and reliability were dependent on thermocouple type, electrothermometer, and water bath temperature (P < .001; modified Levene P < .05). Statistically, the IT-18 and PT-6 thermocouples were not reliable in each electrothermometer; however, these differences were not practically different from each other. The PT-6 thermocouples were more valid than the IT-18s, and both thermocouple types were more valid than the IT-21s, regardless of water bath temperature (P < .001). The validity and reliability of thermocouples interfaced to an electrothermometer under experimental conditions should be tested before data collection. We also recommend that investigators report the validity, the reliability, and the calculated uncertainty (validity + reliability) of their temperature measurements for therapeutic modalities research. With this information, investigators and clinicians will be better able to interpret and compare results and conclusions.

Characterisation of electrical resistance for CMC Materials up to 1200 °C

NASA Astrophysics Data System (ADS)

Stäbler, T.; Böhrk, H.; Voggenreiter, H.

2017-12-01

Damage to thermal protection systems (TPS) during atmospheric re-entry is a severe safety issue, especially when considering re-usability of space transportation systems. There is a need for structural health monitoring systems and non-destructive inspection methods. However, damages are hard to detect. When ceramic matrix composites, in this case carbon fibre reinforced silicon carbide (C/C-SiC), are used as a TPS, the electrical properties of the present semiconductor material can be used for health monitoring, since the resistivity changes with damage, strain and temperature. In this work the electrical resistivity as a function of the material temperature is analysed eliminating effects of thermal electricity and the thermal coefficient of electrical resistance is determined. A sensor network is applied for locally and time resolved monitoring of the 300 mm x 120 mm x 3 mm panel shaped samples. Since the material is used for atmospheric re-entry it needs to be characterised for a wide range of temperatures, in this case as high as 1200 °C. Therefore, experiments in an inductively heated test bench were conducted. Firstly, a reference sample was used with thermocouples for characterising the temperature distribution across the sample surface. Secondly, electrical resistance under heat load was measured, time and spatially resolved. Results will be shown and discussed in terms of resistance dependence on temperature, thermal coefficient of electrical resistance, thermal electricity and electrical path orientation including an analysis on effective conducting cross section. Conversely, the thermal coefficient can also be used to determine the material temperature as a function of electrical resistance.

Vapor chamber with hollow condenser tube heat sink

NASA Astrophysics Data System (ADS)

Ong, K. S.; Haw, P. L.; Lai, K. C.; Tan, K. H.

2017-04-01

Heat pipes are heat transfer devices capable of transferring large quantities of heat effectively and efficiently. A vapor chamber (VC) is a flat heat pipe. A novel VC with hollow condenser tubes embedded on the top of it is proposed. This paper reports on the experimental thermal performance of three VC devices embedded with hollow tubes and employed as heat sinks. The first device consisted of a VC with a single hollow tube while the other two VCs had an array of multi-tubes with different tube lengths. All three devices were tested under natural and force air convection cooling. An electrical resistance heater was employed to provide power inputs of 10 and 40 W. Surface temperatures were measured with thermocouple probes at different locations around the devices. The results show that temperatures increased with heater input while total device thermal resistances decreased. Force convection results in lower temperatures and lower resistance. Dry-out occurs at high input power and with too much condensing area. There appears to be an optimum fill ratio which depended upon dimensions of the VC and also heating power.

Development of ex vivo model for determining temperature distribution in tumor tissue during photothermal therapy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Doughty, Austin; Liu, Shaojie; Zhou, Feifan; Liu, Hong; Chen, Wei R.

2017-02-01

We have recently developed Laser Immunotherapy (LIT), a targeted cancer treatment modality using synergistic application of near-infrared laser irradiation and in situ immunological stimulation. This study further investigates the principles underlying the immune response to LIT treatment by studying immunological impact of the laser photothermal effect in vivo, in vitro, and ex vivo. Tumor cells were stressed in vitro, and samples were collected to analyze protein expression with a Western Blot. Additionally, a tumor model was designed using bovine liver tissue suspended in agarose gel which was treated using laser interstitially and monitored with both proton-resonance frequency shift MR thermometry and thermocouples. From the bovine liver tumor model, we were able to develop the correlation between tissue temperature elevation and laser power and distance from the fiber tip. Similar data was collected by monitoring the temperature of a metastatic mammary tumor in a rat during laser irradiation. Ultimately, these results show that the laser irradiation of LIT leads to clear immunological effects for an effective combination therapy to treat metastatic cancers.

Fatigue crack propagation resistance of virgin and highly crosslinked, thermally treated ultra-high molecular weight polyethylene.

PubMed

Gencur, Sara J; Rimnac, Clare M; Kurtz, Steven M

2006-03-01

To prolong the life of total joint replacements, highly crosslinked ultra-high molecular weight polyethylenes (UHMWPEs) have been introduced to improve the wear resistance of the articulating surfaces. However, there are concerns regarding the loss of ductility and potential loss in fatigue crack propagation (FCP) resistance. The objective of this study was to evaluate the effects of gamma radiation-induced crosslinking with two different post-irradiation thermal treatments on the FCP resistance of UHMWPE. Two highly crosslinked and one virgin UHMWPE treatment groups (ram-extruded, orthopedic grade, GUR 1050) were examined. For the two highly crosslinked treatment groups, UHMWPE rods were exposed to 100 kGy and then underwent post-irradiation thermal processing either above the melt temperature or below the melt temperature (2 h-150 degrees C, 110 degrees C). Compact tension specimens were cyclically loaded to failure and the fatigue crack growth rate, da/dN, vs. cyclic stress intensity factor, DeltaK, behavior was determined and compared between groups. Scanning electron microscopy was used to examine fracture surface characteristics. Crosslinking was found to decrease the ability of UHMWPE to resist crack inception and propagation under cyclic loading. The findings also suggested that annealing as a post-irradiation treatment may be somewhat less detrimental to FCP resistance of UHMWPE than remelting. Scanning electron microscopy examination of the fracture surfaces demonstrated that the virgin treatment group failed in a more ductile manner than the two highly crosslinked treatment groups.

Polarization effects associated with thermal processing of HY-80 structural steel using high-power laser diode array

NASA Astrophysics Data System (ADS)

Wu, Sheldon S. Q.; Baker, Bradford W.; Rotter, Mark D.; Rubenchik, Alexander M.; Wiechec, Maxwell E.; Brown, Zachary M.; Beach, Raymond J.; Matthews, Manyalibo J.

2017-12-01

Localized heating of roughened steel surfaces using highly divergent laser light emitted from high-power laser diode arrays was experimentally demonstrated and compared with theoretical predictions. Polarization dependence was analyzed using Fresnel coefficients to understand the laser-induced temperature rise of HY-80 steel plates under 383- to 612-W laser irradiation. Laser-induced, transient temperature distributions were directly measured using bulk thermocouple probes and thermal imaging. Finite-element analysis yielded quantitative assessment of energy deposition and heat transport in HY-80 steel using absorptivity as a tuning parameter. The extracted absorptivity values ranged from 0.62 to 0.75 for S-polarized and 0.63 to 0.85 for P-polarized light, in agreement with partially oxidized iron surfaces. Microstructural analysis using electron backscatter diffraction revealed a heat affected zone for the highest temperature conditions (612 W, P-polarized) as evidence of rapid quenching and an austenite to martensite transformation. The efficient use of diode arrays for laser-assisted advanced manufacturing technologies, such as hybrid friction stir welding, is discussed.

A systematic study on the effect of electron beam irradiation on structural, electrical, thermo-electric power and magnetic property of LaCoO3

NASA Astrophysics Data System (ADS)

Benedict, Christopher J.; Rao, Ashok; Sanjeev, Ganesh; Okram, G. S.; Babu, P. D.

2016-01-01

In this communication, the effect of electron beam irradiation on the structural, electrical, thermo-electric power and magnetic properties of LaCoO3 cobaltites have been investigated. Rietveld refinement of XRD data reveals that all samples are single phased with rhombohedral structure. Increase in electrical resistivity data is observed with increase in dosage of electron beam irradiation. Analysis of the measured electrical resistivity data indicates that the small polaron hopping model is operative in the high temperature regime for all samples. The Seebeck coefficient (S) of the pristine and the irradiated samples exhibits a crossover from positive to negative values, and a colossal value of Seebeck coefficient (32.65 mV/K) is obtained for pristine sample, however, the value of S decreases with increase in dosage of irradiation. The analysis of Seebeck coefficient data confirms that the small polaron hopping model is operative in the high temperature region. The magnetization results give clear evidence of increase in effective magnetic moment due to increase in dosage of electron beam irradiation.

High level gamma radiation effects on Cernox™ cryogenic temperature sensors

NASA Astrophysics Data System (ADS)

Courts, S. S.

2017-12-01

Cryogenic temperature sensors are used in high energy particle colliders to monitor the temperatures of superconducting magnets, superconducting RF cavities, and cryogen infrastructure. While not intentional, these components are irradiated by leakage radiation during operation of the collider. A common type of cryogenic thermometer used in these applications is the Cernox™ resistance thermometer (CxRT) manufactured by Lake Shore Cryotronics, Inc. This work examines the radiation-induced calibration offsets on CxRT models CX-1050-SD-HT and CX-1080-SD-HT resulting from exposure to very high levels of gamma radiation. Samples from two different wafers of each of the two models tested were subjected to a gamma radiation dose ranging from 10 kGy to 5 MGy. Data were analysed in terms of the temperature-equivalent resistance change between pre- and post-irradiation calibrations. The data show that the resistance of these devices decreased following irradiation resulting in positive temperature offsets across the 1.4 K to 330 K temperature range. Variations in response were observed between wafers of the same CxRT model. Overall, the offsets increased with increasing temperature and increasing gamma radiation dose. At 1.8 K, the average offset increased from 0 mK to +13 mK as total dose increased from 10 kGy to 5 MGy. At 4.2 K, the average offset increased from +4 mK to +33 mK as total dose increased from 10 kGy to 5 MGy. Equivalent temperature offset data are presented over the 1.4 K to 330 K temperature range by CxRT model, wafer, and total gamma dose.

A Highly Thermostable In2O3/ITO Thin Film Thermocouple Prepared via Screen Printing for High Temperature Measurements

PubMed Central

Liu, Yantao; Ren, Wei; Shi, Peng; Liu, Dan; Zhang, Yijun; Liu, Ming; Jing, Weixuan; Tian, Bian; Jiang, Zhuangde

2018-01-01

An In2O3/ITO thin film thermocouple was prepared via screen printing. Glass additives were added to improve the sintering process and to increase the density of the In2O3/ITO films. The surface and cross-sectional images indicate that both the grain size and densification of the ITO and In2O3 films increased with the increase in annealing time. The thermoelectric voltage of the In2O3/ITO thermocouple was 53.5 mV at 1270 °C at the hot junction. The average Seebeck coefficient of the thermocouple was calculated as 44.5 μV/°C. The drift rate of the In2O3/ITO thermocouple was 5.44 °C/h at a measuring time of 10 h at 1270 °C. PMID:29570680

Thermal property change of MOX and UO2 irradiated up to high burnup of 74 GWd/t

NASA Astrophysics Data System (ADS)

Nakae, Nobuo; Akiyama, Hidetoshi; Miura, Hiromichi; Baba, Toshikazu; Kamimura, Katsuichiro; Kurematsu, Shigeru; Kosaka, Yuji; Yoshino, Aya; Kitagawa, Takaaki

2013-09-01

Thermal property is important because it controls fuel behavior under irradiation. The thermal property change at high burnup of more than 70 GWd/t is examined. Two kinds of MOX fuel rods, which were fabricated by MIMAS and SBR methods, and one referenced UO2 fuel rod were used in the experiment. These rods were taken from the pre-irradiated rods (IFA 609/626, of which irradiation test were carried out by Japanese PWR group) and re-fabricated and re-irradiated in HBWR as IFA 702 by JNES. The specification of fuel corresponds to that of 17 × 17 PWR type fuel and the axially averaged linear heat rates (LHR) of MOX rods are 25 kW/m (BOL of IFA 702) and 20 kW/m (EOL of IFA 702). The axial peak burnups achieved are about 74 GWd/t for both of MOX and UO2. Centerline temperature and plenum gas pressure were measured in situ during irradiation. The measured centerline temperature is plotted against LHR at the position where thermocouples are fixed. The slopes of MOX are corresponded to each other, but that of UO2 is higher than those of MOX. This implies that the thermal conductivity of MOX is higher than that of UO2 at high burnup under the condition that the pellet-cladding gap is closed during irradiation. Gap closure is confirmed by the metallography of the postirradiation examinations. It is understood that thermal conductivity of MOX is lower than that of UO2 before irradiation since phonon scattering with plutonium in MOX becomes remarkable. A phonon scattering with plutonium decreases in MOX when burnup proceeds. Thus, thermal conductivity of MOX becomes close to that of UO2. A reverse phenomenon is observed at high burnup region. The phonon scattering with fission products such as Nd and Zr causes a degradation of thermal conductivity of burnt fuel. It might be speculated that this scattering effect causes the phenomenon and the mechanism is discussed here.

Reliability and validity of electrothermometers and associated thermocouples.

PubMed

Jutte, Lisa S; Knight, Kenneth L; Long, Blaine C

2008-02-01

Examine thermocouple model uncertainty (reliability+validity). First, a 3x3 repeated measures design with independent variables electrothermometers and thermocouple model. Second, a 1x3 repeated measures design with independent variable subprobe. Three electrothermometers, 3 thermocouple models, a multi-sensor probe and a mercury thermometer measured a stable water bath. Temperature and absolute temperature differences between thermocouples and a mercury thermometer. Thermocouple uncertainty was greater than manufactures'claims. For all thermocouple models, validity and reliability were better in the Iso-Themex than the Datalogger, but there were no practical differences between models within an electrothermometers. Validity of multi-sensor probes and thermocouples within a probe were not different but were greater than manufacturers'claims. Reliability of multiprobes and thermocouples within a probe were within manufacturers claims. Thermocouple models vary in reliability and validity. Scientists should test and report the uncertainty of their equipment rather than depending on manufactures' claims.

Beam localization in HIFU temperature measurements using thermocouples, with application to cooling by large blood vessels.

PubMed

Dasgupta, Subhashish; Banerjee, Rupak K; Hariharan, Prasanna; Myers, Matthew R

2011-02-01

Experimental studies of thermal effects in high-intensity focused ultrasound (HIFU) procedures are often performed with the aid of fine wire thermocouples positioned within tissue phantoms. Thermocouple measurements are subject to several types of error which must be accounted for before reliable inferences can be made on the basis of the measurements. Thermocouple artifact due to viscous heating is one source of error. A second is the uncertainty regarding the position of the beam relative to the target location or the thermocouple junction, due to the error in positioning the beam at the junction. This paper presents a method for determining the location of the beam relative to a fixed pair of thermocouples. The localization technique reduces the uncertainty introduced by positioning errors associated with very narrow HIFU beams. The technique is presented in the context of an investigation into the effect of blood flow through large vessels on the efficacy of HIFU procedures targeted near the vessel. Application of the beam localization method allowed conclusions regarding the effects of blood flow to be drawn from previously inconclusive (because of localization uncertainties) data. Comparison of the position-adjusted transient temperature profiles for flow rates of 0 and 400ml/min showed that blood flow can reduce temperature elevations by more than 10%, when the HIFU focus is within a 2mm distance from the vessel wall. At acoustic power levels of 17.3 and 24.8W there is a 20- to 70-fold decrease in thermal dose due to the convective cooling effect of blood flow, implying a shrinkage in lesion size. The beam-localization technique also revealed the level of thermocouple artifact as a function of sonication time, providing investigators with an indication of the quality of thermocouple data for a given exposure time. The maximum artifact was found to be double the measured temperature rise, during initial few seconds of sonication. Copyright © 2010 Elsevier B.V. All rights reserved.

Miniature sheathed thermocouples for turbine blade temperature measurement

NASA Technical Reports Server (NTRS)

Holanda, R.; Glawe, G. E.; Krause, L. N.

1974-01-01

An investigation was made of sheathed thermocouples for turbine blade temperature measurements. Tests were performed on the Chromel-Alumel sheathed thermocouples with both two-wire and single-wire configurations. Sheath diameters ranged from 0.25 to 0.76 mm, and temperatures ranged from 1080 to 1250 K. Both steady-state and thermal cycling tests were performed for times up to 450 hr. Special-order and commercial-grade thermocouples were tested. The tests showed that special-order single-wire sheathed thermocouples can be obtained that are reliable and accurate with diameters as small as 0.25 mm. However, all samples of 0.25-mm-diameter sheathed commercial-grade two-wire and single-wire thermocouples that were tested showed unacceptable drift rates for long-duration engine testing programs. The drift rates were about 1 percent in 10 hr. A thermocouple drift test is recommended in addition to the normal acceptance tests in order to select reliable miniature sheathed thermocouples for turbine blade applications.

Ultrasound-guided thermocouple placement for cryosurgery.

PubMed

Abramovits, W; Pruiksma, R; Bose, S

1996-09-01

Although cryosurgical methods have high cure rates, imprecise estimates of both skin lesion depth and destructive temperature front location result in subjective technique in skin malignancy treatments. We evaluated the possibility of newer ultrasound equipment to assist in the precise placement of thermocouples in human skin. DermaScan C ver. 3 ultrasonographic equipment fitted with a sharp focus probe with a frequency of 20 MHz and a scan length of 12.1 mm was used to locate thermocouples with 27- and 30-gauge needles. We successfully and reproducibly located thermocouples and thin needles, and accurately measured their distance from the skin surface. Ultrasound is a useful method for the accurate placement of thermocouples, and needles as thin as 30 gauge for monitoring in cryosurgery.

Localization of focused-ultrasound beams in a tissue phantom, using remote thermocouple arrays.

PubMed

Hariharan, Prasanna; Dibaji, Seyed Ahmad Reza; Banerjee, Rupak K; Nagaraja, Srinidhi; Myers, Matthew R

2014-12-01

In focused-ultrasound procedures such as vessel cauterization or clot lysis, targeting accuracy is critical. To investigate the targeting accuracy of the focused-ultrasound systems, tissue phantoms embedded with thermocouples can be employed. This paper describes a method that utilizes an array of thermocouples to localize the focused ultrasound beam. All of the thermocouples are located away from the beam, so that thermocouple artifacts and sensor interference are minimized. Beam propagation and temperature rise in the phantom are simulated numerically, and an optimization routine calculates the beam location that produces the best agreement between the numerical temperature values and those measured with thermocouples. The accuracy of the method was examined as a function of the array characteristics, including the number of thermocouples in the array and their orientation. For exposures with a 3.3-MHz source, the remote-thermocouple technique was able to predict the focal position to within 0.06 mm. Once the focal location is determined using the localization method, temperatures at desired locations (including the focus) can be estimated from remote thermocouple measurements by curve fitting an analytical solution to the heat equation. Temperature increases in the focal plane were predicted to within 5% agreement with measured values using this method.

Thermocouple design for measuring temperatures of small insects.

PubMed

Hanson, A A; Venette, R C

2013-01-01

Contact thermocouples often are used to measure surface body temperature changes of insects during cold exposure. However, small temperature changes of minute insects can be difficult to detect, particularly during the measurement of supercooling points. We developed two thermocouple designs, which use 0.51 mm diameter or 0.127 mm diameter copper-constantan wires, to improve our ability to resolve insect exotherms. We tested the designs with adults from three parasitoid species: Tetrastichus planipennisi, Spathius agrili, and S. floridanus. These species are <3 mm long and <0.1 mg. Mean exotherms were greater for fine-gauge thermocouples than thick-gauge thermocouples for the smallest species tested, T. planipennisi. This difference was not apparent for larger species S. agrili and S. floridanus. Thermocouple design did not affect the mean supercooling point for any of the species. The cradle thermocouple design developed with the fine gauge wire was reusable and allowed for easy insect recovery after cold exposure.

Comparison of Two Potassium-Filled Gas-Controlled Heat Pipes

NASA Astrophysics Data System (ADS)

Bertiglia, F.; Iacomini, L.; Moro, F.; Merlone, A.

2015-12-01

Calibration by comparison of platinum resistance thermometers and thermocouples requires transfer media capable of providing very good short-term temperature uniformity and temperature stability over a wide temperature range. This paper describes and compares the performance of two potassium-filled gas-controlled heat pipes (GCHP) for operation over the range from 420° C to 900° C. One of the heat pipes has been in operation for more than 10 years having been operated at temperature for thousands of hours, while the other was commissioned in 2010 following recently developed improvements to both the design, assembly, and filling processes. It was found that the two devices, despite differences in age, structure, number of wells, and filling processes, realized the same temperatures within the measurement uncertainty. The results show that the potassium-filled GCHP provides a durable and high-quality transfer medium for performing thermometer calibrations with very low uncertainties, over the difficult high-temperature range from 420° C to 900° C.

Thermocouple shield

DOEpatents

Ripley, Edward B [Knoxville, TN

2009-11-24

A thermocouple shield for use in radio frequency fields. In some embodiments the shield includes an electrically conductive tube that houses a standard thermocouple having a thermocouple junction. The electrically conductive tube protects the thermocouple from damage by an RF (including microwave) field and mitigates erroneous temperature readings due to the microwave or RF field. The thermocouple may be surrounded by a ceramic sheath to further protect the thermocouple. The ceramic sheath is generally formed from a material that is transparent to the wavelength of the microwave or RF energy. The microwave transparency property precludes heating of the ceramic sheath due to microwave coupling, which could affect the accuracy of temperature measurements. The ceramic sheath material is typically an electrically insulating material. The electrically insulative properties of the ceramic sheath help avert electrical arcing, which could damage the thermocouple junction. The electrically conductive tube is generally disposed around the thermocouple junction and disposed around at least a portion of the ceramic sheath. The concepts of the thermocouple shield may be incorporated into an integrated shielded thermocouple assembly.

Chemical coloring on stainless steel by ultrasonic irradiation.

PubMed

Cheng, Zuohui; Xue, Yongqiang; Ju, Hongbin

2018-01-01

To solve the problems of high temperature and non-uniformity of coloring on stainless steel, a new chemical coloring process, applying ultrasonic irradiation to the traditional chemical coloring process, was developed in this paper. The effects of ultrasonic frequency and power density (sound intensity) on chemical coloring on stainless steel were studied. The uniformity of morphology and colors was observed with the help of polarizing microscope and scanning electron microscopy (SEM), and the surface compositions were characterized by X-ray photoelectric spectroscopy (XPS), meanwhile, the wear resistance and the corrosion resistance were investigated, and the effect mechanism of ultrasonic irradiation on chemical coloring was discussed. These results show that in the process of chemical coloring on stainless steel by ultrasonic irradiation, the film composition is the same as the traditional chemical coloring, and this method can significantly enhance the uniformity, the wear and corrosion resistances of the color film and accelerate the coloring rate which makes the coloring temperature reduced to 40°C. The effects of ultrasonic irradiation on the chemical coloring can be attributed to the coloring rate accelerated and the coloring temperature reduced by thermal-effect, the uniformity of coloring film improved by dispersion-effect, and the wear and corrosion resistances of coloring film enhanced by cavitation-effect. Ultrasonic irradiation not only has an extensive application prospect for chemical coloring on stainless steel but also provides an valuable reference for other chemical coloring. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermocouple design for measuring temperatures of small insects

Treesearch

A.A. Hanson; R.C. Venette

2013-01-01

Contact thermocouples often are used to measure surface body temperature changes of insects during cold exposure. However, small temperature changes of minute insects can be difficult to detect, particularly during the measurement of supercooling points. We developed two thermocouple designs, which use 0.51 mm diameter or 0.127 mm diameter copper-constantan wires, to...

Method for analyzing passive silicon carbide thermometry with a continuous dilatometer to determine irradiation temperature

NASA Astrophysics Data System (ADS)

Campbell, Anne A.; Porter, Wallace D.; Katoh, Yutai; Snead, Lance L.

2016-03-01

Silicon carbide is used as a passive post-irradiation temperature monitor because the irradiation defects will anneal out above the irradiation temperature. The irradiation temperature is determined by measuring a property change after isochronal annealing, i.e., lattice spacing, dimensions, electrical resistivity, thermal diffusivity, or bulk density. However, such methods are time-consuming since the steps involved must be performed in a serial manner. This work presents the use of thermal expansion from continuous dilatometry to calculate the SiC irradiation temperature, which is an automated process requiring minimal setup time. Analysis software was written that performs the calculations to obtain the irradiation temperature and removes possible user-introduced error while standardizing the analysis. This method has been compared to an electrical resistivity and isochronal annealing investigation, and the results revealed agreement of the calculated temperatures. These results show that dilatometry is a reliable and less time-intensive process for determining irradiation temperature from passive SiC thermometry.

Study of performance characteristics of noble metal thermocouple materials to 2000 C

NASA Technical Reports Server (NTRS)

Freeze, P. D.; Thomas, D.; Edelman, S.; Stern, J.

1972-01-01

Three performance characteristics of noble metal thermocouples in various environments are discussed. Catalytic effects cause significant errors when noble metal thermocouple materials are exposed to air containing unburned gases in temperature ranges from 25 C to 1500 C. The thermoelectric stability of the iridium 40 rhodium to iridium thermocouple system at 2000 C in an oxidizing medium is described. The effects of large and small temperature gradients on the accuracy and stability of temperature measurements are analyzed.

Self-calibration of a W/Re thermocouple using a miniature Ru-C (1954 °C) eutectic cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ongrai, O.; University of Surrey, Guildford, Surrey; National Institute of Metrology, Klong 5, Klong Luang, Pathumthani

2013-09-11

Previous successful investigations of miniature cobalt-carbon (Co-C, 1324 °C) and palladium-carbon (Pd-C, 1492 °C) high temperature fixed-point cells for thermocouple self-calibration have been reported [1-2]. In the present work, we describe a series of measurements of a miniature ruthenium-carbon (Ru-C) eutectic cell (melting point 1954 °C) to evaluate the repeatability and stability of a W/Re thermocouple (type C) by means of in-situ calibration. A miniature Ru-C eutectic fixed-point cell with outside diameter 14 mm and length 30 mm was fabricated to be used as a self-calibrating device. The performance of the miniature Ru-C cell and the type C thermocouple ismore » presented, including characterization of the stability, repeatability, thermal environment influence, ITS-90 temperature realization and measurement uncertainty.« less

Rocket engine hot-spot detector

NASA Astrophysics Data System (ADS)

Collamore, F. N.

1985-04-01

On high performance devices such as rocket engines it is desirable to know if local hot spots or areas of reduced cooling margin exist. The objective of this program is to design, fabricate and test an electronic hot spot detector capable of sensing local hot spot on the exterior circumference of a regeneratively cooled combustion chamber in order to avoid hardware damage. The electronic hot spot sensor consists of an array of 120 thermocouple elements which are bonded in a flexible belt of polyimide film. The design temperature range is from +30 F to +400 F continuously with an intermittent temperature of 500 F maximum. The thermocouple belt consists of 120 equally spaced copper-Constantan thermocouple junctions which is wrapped around the OMS liquid rocket engine combustion chamber, to monitor temperatures of individual cooling channels. Each thermocouple is located over a cooling channel near the injector end of the combustion chamber. The thermocouple array sensor is held in place by a spring loaded clamp band. Analyses show that in the event of a blocked cooling channel the surface temperature of the chamber over the blocked channel will rise from a normal operating temperature of approx. 300 F to approx. 600 F. The hot spot detector will respond quickly to this change with a response time constant less than 0.05 seconds. The hot spot sensor assembly is fabricated with a laminated construction of layers of Kapton film and an outer protective layer of fiberglass reinforced silicone rubber.

Transparent and Flexible Large-scale Graphene-based Heater

NASA Astrophysics Data System (ADS)

Kang, Junmo; Lee, Changgu; Kim, Young-Jin; Choi, Jae-Boong; Hong, Byung Hee

2011-03-01

We report the application of transparent and flexible heater with high optical transmittance and low sheet resistance using graphene films, showing outstanding thermal and electrical properties. The large-scale graphene films were grown on Cu foil by chemical vapor deposition methods, and transferred to transparent substrates by multiple stacking. The wet chemical doping process enhanced the electrical properties, showing a sheet resistance as low as 35 ohm/sq with 88.5 % transmittance. The temperature response usually depends on the dimension and the sheet resistance of the graphene-based heater. We show that a 4x4 cm2 heater can reach 80& circ; C within 40 seconds and large-scale (9x9 cm2) heater shows uniformly heating performance, which was measured using thermocouple and infra-red camera. These heaters would be very useful for defogging systems and smart windows.

Passive in-situ chemical sensor

DOEpatents

Morrell, Jonathan S [Farragut, TN; Ripley, Edward B [Knoxville, TN

2012-02-14

A chemical sensor for assessing a chemical of interest. In typical embodiments the chemical sensor includes a first thermocouple and second thermocouple. A reactive component is typically disposed proximal to the second thermal couple, and is selected to react with the chemical of interest and generate a temperature variation that may be detected by a comparison of a temperature sensed by the second thermocouple compared with a concurrent temperature detected by the first thermocouple. Further disclosed is a method for assessing a chemical of interest and a method for identifying a reaction temperature for a chemical of interest in a system.

The Influence of Heat Treatment on the Electrical Characteristics of Semi-Insulating SiC Layers Obtained by Irradiating n-SiC with High-Energy Argon Ions

NASA Astrophysics Data System (ADS)

Ivanov, P. A.; Potapov, A. S.; Kudoyarov, M. F.; Kozlovskii, M. A.; Samsonova, T. P.

2018-03-01

Irradiation of crystalline n-type silicon carbide ( n-SiC) with high-energy (53-MeV) argon ions was used to create near-surface semi-insulating ( i-SiC) layers. The influence of subsequent heat treatment on the electrical characteristics of i-SiC layers has been studied. The most high-ohmic ion-irradiated i-SiC layers with room-temperature resistivity of no less than 1.6 × 1013 Ω cm were obtained upon the heat treatment at 600°C, whereas the resistivity of such layers heat-treated at 230°C was about 5 × 107 Ω cm.

Why we should care about soft tissue interfaces when applying ultrasonic diathermy: an experimental and computer simulation study.

PubMed

Omena, Thaís Pionório; Fontes-Pereira, Aldo José; Costa, Rejane Medeiros; Simões, Ricardo Jorge; von Krüger, Marco Antônio; Pereira, Wagner Coelho de Albuquerque

2017-01-01

One goal of therapeutic ultrasound is enabling heat generation in tissue. Ultrasound application protocols typically neglect these processes of absorption and backscatter/reflection at the skin/fat, fat/muscle, and muscle/bone interfaces. The aim of this study was to investigate the heating process at interfaces close to the transducer and the bone with the aid of computer simulation and tissue-mimicking materials (phantoms). The experimental setup consists of physiotherapeutic ultrasound equipment for irradiation, two layers of soft tissue-mimicking material, and one with and one without an additional layer of bone-mimicking material. Thermocouple monitoring is used in both cases. A computational model is used with the experimental parameters in a COMSOL® software platform. The experimental results show significant temperature rise (42 °C) at 10 mm depth, regardless of bone layer presence, diverging 3 °C from the simulated values. The probable causes are thermocouple and transducer heating and interface reverberations. There was no statistical difference in the experimental results with and without the cortical bone for the central thermocouple of the first interface [ t (38) = -1.52; 95% CI = -0.85, 0.12; p  = 14]. Temperature rise (>6 °C) close to the bone layer was lower than predicted (>21 °C), possibly because without the bone layer, thermocouples at 30 mm make contact with the water bath and convection intensifies heat loss; this factor was omitted in the simulation model. This work suggests that more attention should be given to soft tissue layer interfaces in ultrasound therapeutic procedures even in the absence of a close bone layer.

Effect of the Thermocouple on Measuring the Temperature Discontinuity at a Liquid-Vapor Interface.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-07-18

The coupled heat and mass transfer that occurs in evaporation is of interest in a large number of fields such as evaporative cooling, distillation, drying, coating, printing, crystallization, welding, atmospheric processes, and pool fires. The temperature jump that occurs at an evaporating interface is of central importance to understanding this complex process. Over the past three decades, thermocouples have been widely used to measure the interfacial temperature jumps at a liquid-vapor interface during evaporation. However, the reliability of these measurements has not been investigated so far. In this study, a numerical simulation of a thermocouple when it measures the interfacial temperatures at a liquid-vapor interface is conducted to understand the possible effects of the thermocouple on the measured temperature and features in the temperature profile. The differential equations of heat transfer in the solid and fluids as well as the momentum transfer in the fluids are coupled together and solved numerically subject to appropriate boundary conditions between the solid and fluids. The results of the numerical simulation showed that while thermocouples can measure the interfacial temperatures in the liquid correctly, they fail to read the actual interfacial temperatures in the vapor. As the results of our numerical study suggest, the temperature jumps at a liquid-vapor interface measured experimentally by using a thermocouple are larger than what really exists at the interface. For a typical experimental study of evaporation of water at low pressure, it was found that the temperature jumps measured by a thermocouple are overestimated by almost 50%. However, the revised temperature jumps are still in agreement with the statistical rate theory of interfacial transport. As well as addressing the specific application of the liquid-vapor temperature jump, this paper provides significant insight into the role that heat transfer plays in the operation of thermocouples in general.

Method for analyzing passive silicon carbide thermometry with a continuous dilatometer to determine irradiation temperature

DOE PAGES

Campbell, Anne A.; Porter, Wallace D.; Katoh, Yutai; ...

2016-01-14

Silicon carbide is used as a passive post-irradiation temperature monitor because the irradiation defects will anneal out above the irradiation temperature. The irradiation temperature is determined by measuring a property change after isochronal annealing, i.e., lattice spacing, dimensions, electrical resistivity, thermal diffusivity, or bulk density. However, such methods are time-consuming since the steps involved must be performed in a serial manner. This work presents the use of thermal expansion from continuous dilatometry to calculate the SiC irradiation temperature, which is an automated process requiring minimal setup time. Analysis software was written that performs the calculations to obtain the irradiation temperaturemore » and removes possible user-introduced error while standardizing the analysis. In addition, this method has been compared to an electrical resistivity and isochronal annealing investigation, and the results revealed agreement of the calculated temperatures. These results show that dilatometry is a reliable and less time-intensive process for determining irradiation temperature from passive SiC thermometry.« less

Very Fast Temperature Measurement with a Thin Lamp Filament

ERIC Educational Resources Information Center

G. Calza, Gratton, L. M.; Lopez-Arias, T.; Oss, S.

2012-01-01

We construct a thermometer exploiting the electric resistance of the filament of a small lamp used in micro-illumination settings. The instrument may guarantee a response time better than 10 ms, i.e. much faster than commercial thermocouples or other quite expensive devices. This makes our thermometer a useful one in several processes which are…

Hybrid Vehicles

DTIC Science & Technology

2008-12-08

chassis) by a ground strap, wire, welded connection or other suitable low-resistance mechanical connection. Case ground connectors routed from other...environment of a hybrid electric vehicle. Alternative temperature measuring transducers, e.g., thermistors , should be considered when thermocouples are...A 3. Is the ground connection to the chassis or frame mechanically secured by one of the following methods? a. Secured to a spot- welded

In-situ response time testing of thermocouples

NASA Astrophysics Data System (ADS)

Hashemian, H. M.; Petersen, K. M.; Hashemian, M.; Beverly, D. D.; Miller, L. F.

The Loop Current Step Response (LCSR) method has been developed for in situ response time testing of thermocouples and resistance thermometers. A means for measuring the sensor response for actual operating conditions and installation details is provided. This technology is ready to be assembled into an instrument for use in aerospace, nuclear, chemical and other industries where transient temperature measurements are important. The method provides time constant results within better than about 20 percent of value obtained from plunge tests. These results are based on tests performed in water at low flow rates (1M/sec) and in air flow rates ranging from a few meters per second to over a hundred kilometers per hour.

High temperature thermocouple and heat flux gauge using a unique thin film-hardware hot juncture

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1984-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

High-temperature thermocouple and heat flux gauge using a unique thin film-hardware hot junction

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1985-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: application to pure copper, platinum, tungsten, and nickel at very high temperatures.

PubMed

Abadlia, L; Gasser, F; Khalouk, K; Mayoufi, M; Gasser, J G

2014-09-01

In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abadlia, L.; Mayoufi, M.; Gasser, F.

2014-09-15

In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in thismore » paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.« less

Measurement of a surface heat flux and temperature

NASA Astrophysics Data System (ADS)

Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

1994-04-01

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The superimposed thin-film pattern of all six layers is presented. The large pads are for connection with pins used to bring the signal out the back of the ceramic.

Measurement of a surface heat flux and temperature

NASA Technical Reports Server (NTRS)

Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

1994-01-01

The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The superimposed thin-film pattern of all six layers is presented. The large pads are for connection with pins used to bring the signal out the back of the ceramic. In addition to the heat flux measurement, the surface temperature is measured with a platinum resistance layer (RTS). The resistance of this layer increases with increasing temperature. Therefore, these gages simultaneously measure the surface temperature and heat flux. The demonstrated applications include rocket nozzles, SCRAM jet engines, gas turbine engines, boiling heat transfer, flame experiments, basic fluid heat transfer, hypersonic flight, and shock tube testing. The laboratory involves using one of these sensors in a small combustion flame. The sensor is made on a 2.5 cm diameter piece of aluminum nitride ceramic.

Pyrolytic graphite gauge for measuring heat flux

NASA Technical Reports Server (NTRS)

Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

2002-01-01

A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

Development of a fuel-rod simulator and small-diameter thermocouples for high-temperature, high-heat-flux tests in the Gas-Cooled Fast Reactor Core Flow Test Loop

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCulloch, R.W.; MacPherson, R.E.

1983-03-01

The Core Flow Test Loop was constructed to perform many of the safety, core design, and mechanical interaction tests in support of the Gas-Cooled Fast Reactor (GCFR) using electrically heated fuel rod simulators (FRSs). Operation includes many off-normal or postulated accident sequences including transient, high-power, and high-temperature operation. The FRS was developed to survive: (1) hundreds of hours of operation at 200 W/cm/sup 2/, 1000/sup 0/C cladding temperature, and (2) 40 h at 40 W/cm/sup 2/, 1200/sup 0/C cladding temperature. Six 0.5-mm type K sheathed thermocouples were placed inside the FRS cladding to measure steady-state and transient temperatures through cladmore » melting at 1370/sup 0/C.« less

Role of a single shield in thermocouple measurements in hot air flow

NASA Astrophysics Data System (ADS)

Ma, Hongwei; Shi, Lei; Tian, Yangtao

2017-12-01

To investigate the role of a single shield on steady temperature measurement using thermocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In order to compare with the experimental results, a cylindrical computational domain is established, which is the same size with the hot calibration wind-tunnel. In the computational domain, two kinds of thermocouples, the bare-bead and the single-shielded thermocouples, are simulated respectively. Surface temperature distribution and the temperature measurement bias of the two typical thermocouples are compared. The simulation results indicate that: 1) The existence of the shield reduces bead surface heat flux and changes the direction of wires inner heat conduction in a colder surrounding; 2) The existence of the shield reduces the temperature measurement bias both by improving bead surface temperature and by reducing surface temperature gradient; 3) The shield effectively reduces the effect of the ambient temperature on the temperature measurement bias; 4) The shield effectively reduces the influence of airflow velocity on the temperature measurement bias.

Microwave hyperthermia-induced blood-brain barrier alterations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, J.C.; Lin, M.F.

We have studied the interaction of microwaves with the blood-brain barrier in Wistar rats. Indwelling catheters were placed in the femoral vein. Evans blue in isotonic saline was used as a visual indicator of barrier permeation. Irradiation with pulsed 2450-MHz microwaves for 20 min at average power densities of 0.5 to 2600 mW/cm/sup 2/, which resulted in average specific absorption rages (SARs) of 0.04 to 200 mW/g in the brain, did not produce staining, except in regions that normally are highly permeable. When the incident power density was increased to 3000 mW/cm/sup 2/ (SAR of 240 mW/g), extravasation of Evansmore » blue could be seen in the cortex, hippocampus, and midbrain. The rectal temperature, as monitored by a copper-constantan thermocouple, showed a maximum increase of less than 1.0/sup o/C. the brain temperature recorded in a similar group of animals using a non-field-perturbing thermistor exceeded 43/sup o/C. At the higher power density the extravasation depended on the irradition and euthanization times. In one series of experiments, rats were irradiated at 3000 mW/cm/sup 2/ for 5, 10, 15, and 20 min. Immediately after irradiation all except the 5-min animals exhibited increased permeability in some regions of the brain. Brains of rats euthanized 30 min after irradiation were free of Evans blue, while those euthanized 10 and 20 min postirradiation showed significant dye staining but with less intensity than those euthanized immediately after irradiation.« less

Temperature control during regeneration of activated carbon fiber cloth with resistance-feedback.

PubMed

Johnsen, David L; Rood, Mark J

2012-10-16

Electrothermal swing adsorption (ESA) of organic compounds from gas streams with activated carbon fiber cloth (ACFC) reduces emissions to the atmosphere and recovers feedstock for reuse. Local temperature measurement (e.g., with a thermocouple) is typically used to monitor/control adsorbent regeneration cycles. Remote electrical resistance measurement is evaluated here as an alternative to local temperature measurement. ACFC resistance that was modeled based on its physical properties was within 10.5% of the measured resistance values during electrothermal heating. Resistance control was developed based on this measured relationship and used to control temperature to within 2.3% of regeneration set-point temperatures. Isobutane-laden adsorbent was then heated with resistance control. After 2 min of heating, the temperature of the adsorbent with isobutane was 13% less than the adsorbent without isobutane. This difference decreased to 2.1% after 9 min of heating, showing desorption of isobutane. An ACFC cartridge was also heated to 175 °C for 900 cycles with its resistance and adsorption capacity values remaining within 3% and 2%, respectively. This new method to control regeneration power application based on rapid sensing of the adsorbent's resistance removes the need for direct-contact temperature sensors providing a simple, cost-efficient, and long-term regeneration technique for ESA systems.

Development of a temperature measurement system with application to a jet in a cross flow experiment

NASA Technical Reports Server (NTRS)

Wark, C.; Foss, J. F.

1985-01-01

A temperature measurement system, which allows the simultaneous sampling of up to 80 separate thermocouples, was developed. The minimum resolution for the system corresponds to + or - 0.16 C per least significant bit of the A/D converter. The time constant values lambda, for each of the 64 thermocouples, were determined experimentally at 7 mps. Software routines were used to correct the measured temperatures for the effect of lambda for each thermocouple. The temperature measurement system was utilized to study the thermal field of a heated jet discharging perpendicularly into a low and a high disturbance level cross stream for a given momentum flux ratio and for three overheated values. The peak instantaneous temperatures reveal that strong molecular diffusion was operative. Various measures of the thermal field, for the disturbed case, suggest that the jet column remains relatively compact while being buffeted by the ambient turbulence field and that its penetration, into the cross wind, is inhibited by the presence of the strong disturbance field.

INTERNATIONAL REPORT: Revised Values for (t90 - t68) from 630°C to 1064°C

NASA Astrophysics Data System (ADS)

Rusby, R. L.; Hudson, R. P.; Durieux, M.

1994-01-01

A revised table of differences (t90 - t68) between values of temperature on the International Temperature Scale of 1990, ITS-90, and the corresponding values on the International Practical Temperature Scale of 1968, IPTS-68, is published at the request of the Comité Consultatif de Thermométrie (CCT). The revision affects only the range 630°C to 1064°C, where the IPTS-68 specified the use of platinum-10% rhodium versus platinum thermocouples. It follows from new intercomparisons of thermocouples carrying IPTS-68 calibrations with platinum resistance thermometers and radiation thermometers calibrated in accordance with the ITS-90. The largest change occurs at 760°C, where the difference formerly tabulated as 0,36°C is now 0,04°C. The revision concerns only the assessment of the differences between the ITS-90 and the IPTS-68, and does not affect the ITS-90 in any way.

Circuit for monitoring temperature of high-voltage equipment

DOEpatents

Jacobs, Martin E.

1976-01-01

This invention relates to an improved circuit for measuring temperature in a region at high electric potential and generating a read-out of the same in a region at lower potential. The circuit is specially designed to combine high sensitivity, stability, and accuracy. A major portion of the circuit situated in the high-potential region can take the form of an integrated circuit. The preferred form of the circuit includes an input section which is situated in the high-potential region and comprises a temperature-compensated thermocouple circuit for sensing temperature, an oscillator circuit for generating a train of ramp voltages whose rise time varies inversely with the thermocouple output, a comparator and switching circuit for converting the oscillator output to pulses whose frequency is proportional to the thermocouple output, and a light-emitting diode which is energized by these pulses. An optical coupling transmits the light pulses generated by the diode to an output section of the circuit, situated in a region at ground. The output section comprises means for converting the transmitted pulses to electrical pulses of corresponding frequency, means for amplifying the electrical pulses, and means for displaying the frequency of the same. The preferred embodiment of the overall circuit is designed so that the frequency of the output signal in hertz and tenths of hertz is equal to the sensed temperature in degrees and tenths of degrees.

Determination of a response function of a thermocouple using a short acoustic pulse.

PubMed

Tashiro, Yusuke; Biwa, Tetsushi; Yazaki, Taichi

2007-04-01

This paper reports on an experimental technique to determine a response function of a thermocouple using a short acoustic pulse wave. A pulse of 10 ms is generated in a tube filled with 1 bar helium gas. The temperature is measured using the thermocouple. The reference temperature is deduced from the measured pressure on the basis of a laminar oscillating flow theory. The response function of the thermocouple is obtained as a function of frequency below 50 Hz through a comparison between the measured and reference temperatures.

Errors induced by catalytic effects in premixed flame temperature measurements

NASA Astrophysics Data System (ADS)

Pita, G. P. A.; Nina, M. N. R.

The evaluation of instantaneous temperature in a premixed flame using fine-wire Pt/Pt-(13 pct)Rh thermocouples was found to be subject to significant errors due to catalytic effects. An experimental study was undertaken to assess the influence of local fuel/air ratio, thermocouple wire diameter, and gas velocity on the thermocouple reading errors induced by the catalytic surface reactions. Measurements made with both coated and uncoated thermocouples showed that the catalytic effect imposes severe limitations on the accuracy of mean and fluctuating gas temperature in the radical-rich flame zone.

Advanced Microscopic Integrated Thermocouple Arrays

NASA Technical Reports Server (NTRS)

Pettigrew, Penny J.

1999-01-01

The purpose of this research is to develop and refine a technique for making microscopic thermocouple arrays for use in measuring the temperature gradient across a solid-liquid interface during the solidification process. Current thermocouple technology does not allow for real-time measurements across the interface due to the prohibitive size of available thermocouples. Microscopic thermocouple arrays will offer a much greater accuracy and resolution of temperature measurements across the solid-liquid interface which will lead to a better characterization of the solidification process and interface reaction which affect the properties of the resulting material.

Dependence of defect introduction on temperature and resistivity and some long-term annealing effects

NASA Technical Reports Server (NTRS)

Brucker, G. J.

1971-01-01

The effort reported here represents data of lithium properties in bulk-silicon samples before and after irradiation for analytical information required to characterize the interactions of lithium with radiation-induced defects in silicon. A model of the damage and recovery mechanisms in irradiated-lithium-containing solar cells is developed based on making measurements of the Hall coefficient and resistivity of samples irradiated by 1-MeV electrons. Experiments on bulk samples included Hall coefficient and resistivity measurements taken as a function of: (1) bombardment temperature, (2) resistivity, (3) fluence, (4) oxygen concentration, and (5) annealing time at temperatures from 300 to 373 K.

Effect of neutron irradiation on the thermoelectric properties of SiGe alloys

NASA Technical Reports Server (NTRS)

Vandersande, Jan W.; Mccormack, Joe; Zoltan, Andy; Farmer, John

1990-01-01

Zone-leveled and hot-pressed n- and p-type Si80Ge20 alloys were irradiated with neutrons to a fluence of 4 x 1018 n/sq cm and to a fluence of 5.4 x 1019 n/sq cm at a temperature of approximately 200-300 C. The effect of neutron irradiation on the thermoelectric properties of these alloys was evaluated. The carrier concentration and mobility (and hence the resistivity) were measured at room temperature while the thermal diffusivity was measured at 177-192 C both before and after the irradiation and after each subsequent 2-h heat treatment at 350 C, 600, and 1000 C. The irradiation increased the resistivity significantly, but the thermal conductivity decreased only by about 10-15 percent. This tends to indicate that the radiation produced only small defects (single pairs and small vacancy chains). The samples all returned to almost exactly their preirradiation state after the 1000 C anneal. This indicates that SiGe alloys can be operated in this neutron fluence at high temperatures without a degradation of thermoelectric properties.

Atom probe tomography analysis of high dose MA957 at selected irradiation temperatures

NASA Astrophysics Data System (ADS)

Bailey, Nathan A.; Stergar, Erich; Toloczko, Mychailo; Hosemann, Peter

2015-04-01

Oxide dispersion strengthened (ODS) alloys are meritable structural materials for nuclear reactor systems due to the exemplary resistance to radiation damage and high temperature creep. Summarized in this work are atom probe tomography (APT) investigations on a heat of MA957 that underwent irradiation in the form of in-reactor creep specimens in the Fast Flux Test Facility-Materials Open Test Assembly (FFTF-MOTA) for the Liquid Metal Fast Breeder Reactor (LMFBR) program. The oxide precipitates appear stable under irradiation at elevated temperature over extended periods of time. Nominally, the precipitate chemistry is unchanged by the accumulated dose; although, evidence suggests that ballistic dissolution and reformation processes are occurring at all irradiation temperatures. At 412 °C-109 dpa, chromium enrichments - consistent with the α‧ phase - appear between the oxide precipitates, indicating radiation induced segregation. Grain boundaries, enriched with several elements including nickel and titanium, are observed at all irradiation conditions. At 412 °C-109 dpa, the grain boundaries are also enriched in molecular titanium oxide (TiO).

Irradiation of three T-111 clad uranium nitride fuel pins for 8070 hours at 990 C (1815 F)

NASA Technical Reports Server (NTRS)

Slaby, J. G.; Siegel, B. L.; Gedeon, L.; Galbo, R. J.

1973-01-01

The design and successful operation of three tantalum alloy (Ta-8W-2Hf) clad uranium mononitride (UN) fuel pins irradiated for 8070 hr at 990 C (1815 F) is described. Two pin diameters having measured burnups of 0.47 and 0.90 uranium atom percent were tested. No clad failures or swelling was detected; however, postirradiation clad samples tested failed with 1 percent strain. The fuel density decrease was 2 percent, and the fission gas release was less than 0.05 percent. Isotropic fuel swelling, which averaged about 0.5 percent, was less than fuel pin assembly clearances. Thus the clad was not strained. Thermocouples with a modified hot zone operated at average temperatures to 1100 C (2012 F) without failure. Factors that influence the ability to maintain uniform clad temperature as well as the results of the heat transfer calculations are discussed.

Measuring temperature rise during orthopaedic surgical procedures.

PubMed

Manoogian, Sarah; Lee, Adam K; Widmaier, James C

2016-09-01

A reliable means for measuring temperatures generated during surgical procedures is needed to recommend best practices for inserting fixation devices and minimizing the risk of osteonecrosis. Twenty four screw tests for three surgical procedures were conducted using the four thermocouples in the bone and one thermocouple in the screw. The maximum temperature rise recorded from the thermocouple in the screw (92.7±8.9°C, 158.7±20.9°C, 204.4±35.2°C) was consistently higher than the average temperature rise recorded in the bone (31.8±9.3°C, 44.9±12.4°C, 77.3±12.7°C). The same overall trend between the temperatures that resulted from three screw insertion procedures was recorded with significant statistical analyses using either the thermocouple in the screw or the average of several in-bone thermocouples. Placing a single thermocouple in the bone was determined to have limitations in accurately comparing temperatures from different external fixation screw insertion procedures. Using the preferred measurement techniques, a standard screw with a predrilled hole was found to have the lowest maximum temperatures for the shortest duration compared to the other two insertion procedures. Future studies evaluating bone temperature increase need to use reliable temperature measurements for recommending best practices to surgeons. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

High temperature blackbody BB2000/40 for calibration of radiation thermometers and thermocouple

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogarev, S. A.; Khlevnoy, B. B.; Samoylov, M. L.

2013-09-11

The cavity-type high temperature blackbody (HTBB) models of BB3200/3500 series are the most spread among metrological institutes worldwide as sources for radiometry and radiation thermometry, due to their ultra high working temperatures, high emissivity and stability. The materials of radiating cavities are graphite, pyrolytic graphite (PG) and their combination. The paper describes BB2000/40 blackbody with graphite-tube cavity that was developed for calibration of radiation thermometers at SCEI (Singapore). The peculiarity of BB2000/40 is a possibility to use it, besides calibration of pyrometers, as an instrument for thermocouples calibration. Operating within the temperature range from 900 °C to 2000 °C, themore » blackbody has a wide cavity opening of 40 mm. Emissivity of the cavity, with PG heater rings replaced partly by graphite elements, was estimated as 0.998 ± 0.0015 in the spectral range from 350 nm to 2000 nm. The uniformity along the cavity axis, accounting for 10 °C, was measured using a B-type thermocouple at 1500 °C. The BB2000/40, if necessary, can be easily modified, by replacing the graphite radiator with a set of PG rings, to be able to reach temperatures as high as 3200 °C. The HTBB utilizes an optical feedback system which allows temperature stabilization within 0.1 °C. This rear-view feedback allows the whole HTBB aperture to be used for measurements.« less

Irradiation response of commercial, high-Tc superconducting tapes: Electromagnetic transport properties

DOE PAGES

Gapud, A. A.; Greenwood, N. T.; Alexander, J. A.; ...

2015-07-01

Effects of low dose irradiation on the electrical transport current properties of commercially available high-temperature superconducting, coated-conductor tapes were investigated, in view of potential applications in the irradiative environment of fusion reactors. Three different tapes, each with unique as-grown flux-pinning structures, were irradiated with Au and Ni ions at energies that provide a range of damage effects, with accumulated damage levels near that expected for conductors in a fusion reactor environment. Measurements using transport current determined the pre- and post-irradiation resistivity, critical current density, and pinning force density, yielding critical temperatures, irreversibility lines, and inferred vortex creep rates. Results showmore » that at the irradiation damage levels tested, any detriment to as-grown pre-irradiation properties is modest; indeed in one case already-superior pinning forces are enhanced, leading to higher critical currents.« less

Method for collecting thermocouple data via secured shell over a wireless local area network in real time

NASA Astrophysics Data System (ADS)

Arnold, F.; DeMallie, I.; Florence, L.; Kashinski, D. O.

2015-03-01

This manuscript addresses the design, hardware details, construction, and programming of an apparatus allowing an experimenter to monitor and record high-temperature thermocouple measurements of dynamic systems in real time. The apparatus uses wireless network technology to bridge the gap between a dynamic (moving) sample frame and the static laboratory frame. Our design is a custom solution applied to samples that rotate through large angular displacements where hard-wired and typical slip-ring solutions are not practical because of noise considerations. The apparatus consists of a Raspberry PI mini-Linux computer, an Arduino micro-controller, an Ocean Controls thermocouple multiplexer shield, and k-type thermocouples.

Method for collecting thermocouple data via secured shell over a wireless local area network in real time.

PubMed

Arnold, F; DeMallie, I; Florence, L; Kashinski, D O

2015-03-01

This manuscript addresses the design, hardware details, construction, and programming of an apparatus allowing an experimenter to monitor and record high-temperature thermocouple measurements of dynamic systems in real time. The apparatus uses wireless network technology to bridge the gap between a dynamic (moving) sample frame and the static laboratory frame. Our design is a custom solution applied to samples that rotate through large angular displacements where hard-wired and typical slip-ring solutions are not practical because of noise considerations. The apparatus consists of a Raspberry PI mini-Linux computer, an Arduino micro-controller, an Ocean Controls thermocouple multiplexer shield, and k-type thermocouples.

Uncertainty of a hybrid surface temperature sensor for silicon wafers and comparison with an embedded thermocouple.

PubMed

Iuchi, Tohru; Gogami, Atsushi

2009-12-01

We have developed a user-friendly hybrid surface temperature sensor. The uncertainties of temperature readings associated with this sensor and a thermocouple embedded in a silicon wafer are compared. The expanded uncertainties (k=2) of the hybrid temperature sensor and the embedded thermocouple are 2.11 and 2.37 K, respectively, in the temperature range between 600 and 1000 K. In the present paper, the uncertainty evaluation and the sources of uncertainty are described.

PVD coating for optical applications on temperature-resistant thermoplastics

NASA Astrophysics Data System (ADS)

Munzert, Peter; Schulz, Ulrike; Kaiser, Norbert

2004-02-01

The performance of the high temperature resistant polymers Pleximid, APEC and Ultrason as substrate materials in plasma-assisted physical vapor deposition processes was studied and compared with well-known thermoplastics for optical applications. Different effects of UV irradiation and plasma exposure on the polymers' optical features, surface energy and adhesion properties for oxide layers, typically used for interference multilayer coatings, are shown.

NUCLEAR REACTOR SLUG PROVIDED WITH THERMOCOUPLE

DOEpatents

Kanne, W.R.

1958-10-14

A temperature measuring apparatus is described for use in a reactor. In this invention a cylindrlcal fuel slug is provided with an axial bore in which is disposed a thermocouple. The lead wires extend to a remote indicating device which indicates the temperature in the fuel element measured by the thermocouple.

DOE Office of Scientific and Technical Information (OSTI.GOV)

El Atwani, Osman; Hinks, Jonathan; Greaves, Graeme

Nanocrystalline metals are considered highly radiation-resistant materials due to their large grain boundary areas. Here, the existence of a grain size threshold for enhanced irradiation resistance in high-temperature helium-irradiated nanocrystalline and ultrafine tungsten is demonstrated. Average bubble density, projected bubble area and the corresponding change in volume were measured via transmission electron microscopy and plotted as a function of grain size for two ion fluences. Nanocrystalline grains of less than 35 nm size possess ~10–20 times lower change in volume than ultrafine grains and this is discussed in terms of the grain boundaries defect sink efficiency.

Construction of a Cr3C2-C Peritectic Point Cell for Thermocouple Calibration

NASA Astrophysics Data System (ADS)

Ogura, Hideki; Deuze, Thierry; Morice, Ronan; Ridoux, Pascal; Filtz, Jean-Remy

The melting points of Cr3C2-C peritectic (1826°C) and Cr7C3-Cr3C2 eutectic (1742°C) alloys as materials for high-temperature fixed point cells are investigated for the use of thermocouple calibration. Pretests are performed to establish a suitable procedure for constructing contact thermometry cells based on such chromium-carbon mixtures. Two cells are constructed following two different possible procedures. The above two melting points are successfully observed for one of these cells using tungsten-rhenium alloy thermocouples.

Thread-Mounted Thermocouple

NASA Technical Reports Server (NTRS)

Ward, Stanley W.

1988-01-01

Thread-mounted thermocouple developed to accurately measure temperature of surrounding material. Comprised of threaded rod or bolt drilled along length, dual-hole ceramic insulator rod, thermocouple wire, optional ceramic filler, and epoxy resin. In contact with and takes average temperature of, surrounding material. Fabricated easily in size and metal to suit particular application. Because of simplicity and ability to measure average temperature, widespread use of design foreseen in varity of applications.

The effect of ultrasound irradiation on the convective heat transfer rate during immersion cooling of a stationary sphere.

PubMed

Kiani, Hossein; Sun, Da-Wen; Zhang, Zhihang

2012-11-01

It has been proven that ultrasound irradiation can enhance the rate of heat transfer processes. The objective of this work was to study the heat transfer phenomenon, mainly the heat exchange at the surface, as affected by ultrasound irradiation around a stationary copper sphere (k=386W m(-1)K(-1), C(p)=384J kg(-1)K(-1), ρ=8660kg m(-3)) during cooling. The sphere (0.01m in diameter) was immersed in an ethylene glycol-water mixture (-10°C) in an ultrasonic cooling system that included a refrigerated circulator, a flow meter, an ultrasound generator and an ultrasonic bath. The temperature of the sphere was recorded using a data logger equipped with a T-type thermocouple in the center of the sphere. The temperature of the cooling medium was also monitored by four thermocouples situated at different places in the bath. The sphere was located at different positions (0.02, 0.04 and 0.06m) above the transducer surface of the bath calculated considering the center of the sphere as the center of the reference system and was exposed to different intensities of ultrasound (0, 120, 190, 450, 890, 1800, 2800, 3400 and 4100W m(-2)) during cooling. The frequency of the ultrasound was 25kHz. It was demonstrated that ultrasound irradiation can increase the rate of heat transfer significantly, resulting in considerably shorter cooling times. Higher intensities caused higher cooling rates, and Nu values were increased from about 23-27 to 25-108 depending on the intensity of ultrasound and the position of the sphere. However, high intensities of ultrasound led to the generation of heat at the surface of the sphere, thus limiting the lowest final temperature achieved. An analytical solution was developed considering the heat generation and was fitted to the experimental data with R(2) values in the range of 0.910-0.998. Visual observations revealed that both cavitation and acoustic streaming were important for heat transfer phenomenon. Cavitation clouds at the surface of the sphere were the main cause of heating effect. The results showed that closer distances to the transducer surface showed higher cooling rates. On the other hand, despite having a bigger distance from the transducer, when the sphere was located close to the gas-liquid interface the enhancement factor of heat transfer was higher. Ultrasound irradiation showed promising effect for the enhancement of convective heat transfer rate during immersion cooling. More investigations are required to demonstrate the behavior of ultrasound assisted heat transfer and resolve the proper way of the application of ultrasound to assist the cooling and/or freezing processes. Copyright © 2012 Elsevier B.V. All rights reserved.

An "Inefficient Fin" Non-Dimensional Parameter to Measure Gas Temperatures Efficiently

NASA Technical Reports Server (NTRS)

Lemieux, Patrick; Murray, William; Cooke, Terry; Gerhardt, James

2012-01-01

A gas containment vessel that is not in thermal equilibrium with the bulk gas can affect its temperature measurement. The physical nature of many gas dynamics experiments often makes the accurate measurement of temperature a challenge. The environment itself typically requires that the thermocouple be sheathed, both to protect the wires and hot junction of the instrument from their environment, and to provide a smooth, rigid surface for pressure sealing of the enclosure. However, that enclosure may also be much colder than the gas to be sensed, or vice-versa. Either way, the effect of such gradients is to potentially skew the temperature measurements themselves, since heat may then be conducted by the instrument. Thermocouple designers traditionally address this problem by insulating the sheath from the thermocouple leads and hot junction as much as possible. The thermocouple leads are typically packed in a ceramic powder inside the sheath, protecting them somewhat from temperature gradients along the sheath, but there is no effective mechanism to shield the sheath from the enclosure body itself. Standard practice dictates that thermocouples be used in installations that do not present large thermal gradients along the probe. If this conduction dominates heat transfer near the tip of the probe, then temperature measurements may be expected to be skewed. While the same problem may be experienced in the measurement of temperature at various points within a solid in a gradient, it tends to be aggravated in the measurements of gas temperature, since heat transfer dependent on convection is often less efficient than conduction along the thermocouple. The proposed solution is an inefficient fin thermocouple probe. Conventional wisdom suggests that in many experiments where gas flows through an enclosure (e.g., flow in pipe, manifold, nozzle, etc.), the thermocouple be introduced flush to the surface, so as not to interfere with the flow. In practice, however, many such experiments take place where the flow is already turbulent, so that a protruding thermocouple probe has a negligible effect on the flow characteristics. The key question then becomes just how far into the flow should a thermocouple protrude in order to properly sense the gas temperature at that point. Modeling the thermocouple as an "inefficient fin" directly addresses this question. The appropriate assumptions in this case are: one-dimensional conduction along the fin; steady-state, constant, and homogeneous thermal conductivity; negligible radiation; and a uniform, constant heat transfer coefficient over the probe surface. It is noted that the nature of the ceramic-filled probe makes the key assumption of homogeneous thermal conductivity that much more conservative.

Optimal dye concentration and irradiance for laser-assisted vascular anastomosis.

PubMed

Ren, Zhen; Xie, Hua; Lagerquist, Kathryn A; Burke, Allen; Prahl, Scott; Gregory, Kenton W; Furnary, Anthony P

2004-04-01

This investigation was done in order to find optimal indocyanine green (ICG) concentration and energy irradiance in laser vascular welding. Many studies have shown that laser tissue welding with albumin solder/ICG may be an effective technique in surgical reconstruction. However, there are few reports regarding optimal laser settings and concentrations of ICG within the albumin solder in laser-assisted vascular anastomosis. Porcine carotid artery strips (n = 120) were welded in end-to-end by diode laser with 50% albumin solder of 0.01, 0.1, and 1.0 mM ICG at irradiance of 27.7, 56.7, and 76.9 W/cm(2), respectively. Temperature was measured by inserting thermocouples outside and inside the vessel. Tensile strength and histology were studied. Temperature and strength of the anastomosis significantly decreased (all p < 0.05) with increasing ICG concentration at 56.7 W/cm(2). Histological study showed minimal thermal injury limited to adventitia and no appreciable difference between all groups. ICG concentration within solder is the most important factor affecting both vascular temperature and tensile strength. The optimal balance between strength and minimal thermal injury may be achieved primarily at 56.7 W/cm(2) and 0.01 mM ICG.

Development of ex vivo model for determining temperature distribution in tumor tissue during photothermal therapy

NASA Astrophysics Data System (ADS)

Liu, Shaojie; Doughty, Austin; Mesiya, Sana; Pettitt, Alex; Zhou, Feifan; Chen, Wei R.

2017-02-01

Temperature distribution in tissue is a crucial factor in determining the outcome of photothermal therapy in cancer treatment. In order to investigate the temperature distribution in tumor tissue during laser irradiation, we developed a novel ex vivo device to simulate the photothermal therapy on tumors. A 35°C, a thermostatic incubator was used to provide a simulation environment for body temperature of live animals. Different biological tissues (chicken breast and bovine liver) were buried inside a tissue-simulating gel and considered as tumor tissues. An 805-nm laser was used to irradiate the target tissue. A fiber with an interstitial cylindrical diffuser (10 mm) was directly inserted in the center of the tissue, and the needle probes of a thermocouple were inserted into the tissue paralleling the laser fiber at different distances to measure the temperature distribution. All of the procedures were performed in the incubator. Based on the results of this study, the temperature distribution in bovine liver is similar to that of tumor tissue under photothermal therapy with the same doses. Therefore, the developed model using bovine liver for determining temperature distribution can be used during interstitial photothermal therapy.

Thermal protection system ablation sensor

NASA Technical Reports Server (NTRS)

Gorbunov, Sergey (Inventor); Martinez, Edward R. (Inventor); Scott, James B. (Inventor); Oishi, Tomomi (Inventor); Fu, Johnny (Inventor); Mach, Joseph G. (Inventor); Santos, Jose B. (Inventor)

2011-01-01

An isotherm sensor tracks space vehicle temperatures by a thermal protection system (TPS) material during vehicle re-entry as a function of time, and surface recession through calibration, calculation, analysis and exposed surface modeling. Sensor design includes: two resistive conductors, wound around a tube, with a first end of each conductor connected to a constant current source, and second ends electrically insulated from each other by a selected material that becomes an electrically conductive char at higher temperatures to thereby complete an electrical circuit. The sensor conductors become shorter as ablation proceeds and reduced resistance in the completed electrical circuit (proportional to conductor length) is continually monitored, using measured end-to-end voltage change or current in the circuit. Thermocouple and/or piezoelectric measurements provide consistency checks on local temperatures.

Temperature characterisation of the CLOUD chamber at CERN

NASA Astrophysics Data System (ADS)

Dias, A. M.; Almeida, J.; Kirkby, J.; Mathot, S.; Onnela, A.; Vogel, A.; Ehrhart, S.

2014-12-01

Temperature stability, uniformity and absolute scale inside the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN are important for experiments on aerosol particle nucleation and ice/liquid cloud formation. In order to measure the air temperature, a comprehensive set of arrays ("strings") of platinum resistance thermometers, thermocouples and optical sensors have been installed inside the 26 m3 chamber. The thermal sensors must meet several challenging design requirements: ultra-clean materials, 0.01 K measurement sensitivity, high absolute precision (<0.1 K), 200 K - 373 K range, ability to operate in high electric fields (20 kV/m), and fast response in air (~1 s) in order to measure rapid changes of temperature during ice/liquid cloud formation in the chamber by adiabatic pressure reductions. This presentation will focus on the design of the thermometer strings and the thermal performance of the chamber during the CLOUD8 and CLOUD9 campaigns, 2013-2014, together with the planned upgrades of the CLOUD thermal system.

A comprehensive survey of thermoelectric homogeneity of commonly used thermocouple types

NASA Astrophysics Data System (ADS)

Machin, Jonathan; Tucker, Declan; Pearce, Jonathan V.

2018-06-01

Thermocouples are widely used as temperature sensors in industry. The electromotive force generated by a thermocouple is produced in a temperature gradient and not at the thermocouple tip. This means that the thermoelectric inhomogeneity represents one of the most important contributions to the overall measurement uncertainty associated with thermocouples. To characterise this effect, and to provide some general recommendations concerning the magnitude of this contribution to use when formulating uncertainty analyses, a comprehensive literature survey has been performed. Significant information was found for Types K, N, R, S, B, Pt/Pd, Au/Pt and various other Pt/Rh thermocouples. In the case of Type K and N thermocouples, the survey has been augmented by a substantial amount of data based on calibrations of mineral-insulated, metal-sheathed thermocouple cable reels from thermocouple manufacturers. Some general conclusions are drawn and outline recommendations given concerning typical values for the uncertainty arising from thermoelectric inhomogeneity for the most widely used thermocouple types in the as-new state. It is stressed that these recommendations should only be heeded when individual homogeneity measurements are not possible. It is also stressed that the homogeneity can deteriorate rapidly during use, particularly for base metal thermocouples.

Electrical conductivity of In₂O₃ and Ga₂O₃ after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level.

PubMed

Vines, Lasse; Bhoodoo, Chidanand; von Wenckstern, Holger; Grundmann, Marius

2017-11-29

The evolution of sheet resistance of n-type In2O3 and Ga2O3 exposed to bombardment with MeV 12C and 28Si ions at 35 K is studied in situ. While the sheet resistance of Ga2O3 increased by more than 8 orders of magnitude as a result of ion irradiation, In2O3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga2O3 remained highly resistive, while In2O3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to 2 1012 cm2. A model where larger defect complexes preferentially produce donor like defects in In2O3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed. © 2017 IOP Publishing Ltd.

Integration of extracellular matrix with chitosan adhesive film for sutureless tissue fixation.

PubMed

Lauto, Antonio

2009-07-01

Extracellular matrices (ECMs) are currently applied in reconstructive surgery to enhance wound healing and tissue remodelling. Sutures and staples are usually employed to stabilize ECM on tissue although they may damage the matrix structure. In this investigation, a novel biocompatible bandage was developed to fix ECM on tissue without sutures. An adhesive film, based on chitosan, was integrated with small intestine submucosa (SIS) in a single bandage strip. This bandage was bonded to sheep small intestine upon laser irradiation of the chitosan film (P = 0.12 W, Fluence = 46+/-1 J/cm(2)) to assess tissue adhesion strength. Thermocouples were used to estimate temperatures under SIS during laser irradiation. Bandage strips were also mechanically tested to evaluate their tensile strength before and after irradiation. The bandage successfully bonded to intestine achieving a shear stress of 9.6+/- 1.6 kPa (n = 15). During laser irradiation, the temperature increased modestly to 31+/-2 degrees C (n = 14) beneath the ECM portion of the bandage. The bandage withstood a tensile strength of 3,122+/-780 and 3,384+/-791 kPa, before and after laser irradiation respectively (n = 10, P = 0.47, t-test). The SIS-chitosan bandage bonded effectively to tissue without sutures and preserved the ECM structure avoiding irreversible thermal denaturation of imbedded bioactive proteins.

Microstructure and hardness evolution of nanochannel W films irradiated by helium at high temperature

NASA Astrophysics Data System (ADS)

Qin, Wenjing; Wang, Yongqiang; Tang, Ming; Ren, Feng; Fu, Qiang; Cai, Guangxu; Dong, Lan; Hu, Lulu; Wei, Guo; Jiang, Changzhong

2018-04-01

Plasma facing materials (PFMs) face one of the most serious challenges in fusion reactors, including unprecedented harsh environment such as 14.1 MeV neutron and transmutation gas irradiation at high temperature. Tungsten (W) is considered to be one of the most promising PFM, however, virtually insolubility of helium (He) in W causes new material issues such as He bubbles and W "fuzz" microstructure. In our previous studies, we presented a new strategy using nanochannel structure designed in the W film to increase the releasing of He atoms and thus to minimize the He nucleation and "fuzz" formation behavior. In this work, we report the further study on the diffusion of He atoms in the nanochannel W films irradiated at a high temperature of 600 °C. More specifically, the temperature influences on the formation and growth of He bubbles, the lattice swelling, and the mechanical properties of the nanochannel W films were investigated. Compared with the bulk W, the nanochannel W films possessed smaller bubble size and lower bubble areal density, indicating that noticeable amounts of He atoms have been released out along the nanochannels during the high temperature irradiations. Thus, with lower He concentration in the nanochannel W films, the formation of the bubble superlattice is delayed, which suppresses the lattice swelling and reduces hardening. These aspects indicate the nanochannel W films have better radiation resistance even at high temperature irradiations.

40 CFR 63.5150 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2013 CFR

2013-07-01

... thermocouple or temperature sensor in the combustion chamber at a location in the combustion zone. (iii) For a... according to § 63.5160(d)(3)(ii)(A) and (B), then you must install the thermocouples or temperature sensors... the thermocouple or temperature sensor in the vent stream at the nearest feasible point to the inlet...

40 CFR 63.5150 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2014 CFR

2014-07-01

... thermocouple or temperature sensor in the combustion chamber at a location in the combustion zone. (iii) For a... according to § 63.5160(d)(3)(ii)(A) and (B), then you must install the thermocouples or temperature sensors... the thermocouple or temperature sensor in the vent stream at the nearest feasible point to the inlet...

40 CFR 63.5150 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2012 CFR

2012-07-01

... thermocouple or temperature sensor in the combustion chamber at a location in the combustion zone. (iii) For a... according to § 63.5160(d)(3)(ii)(A) and (B), then you must install the thermocouples or temperature sensors... the thermocouple or temperature sensor in the vent stream at the nearest feasible point to the inlet...

Temperature and SAR measurements in deep-body hyperthermia with thermocouple thermometry.

PubMed

De Leeuw, A A; Crezee, J; Lagendijk, J J

1993-01-01

Multisensor (7-14) thermocouple thermometry is used at our department for temperature measurement with our 'Coaxial TEM' regional hyperthermia system. A special design of the thermometry system with high resolution (0.005 degrees C) and fast data-acquisition (all channels within 320 ms) together with a pulsed power technique allows assessment of specific absorption rate (SAR) information in patients along catheter tracks. A disadvantage of thermocouple thermometry, EM interference, is almost entirely eliminated by application of absorbing ferrite beads around the probe leads. We investigated the effect of remaining disturbance on the temperature decay after power-off, both experimentally in phantoms and in the clinic, and with numerical simulations. Probe and tissue characteristics influence the response time tau dist of the decay of the disturbance. In our clinical practice a normal pulse sequence is 50 s power-on, 10 s power-off: a response time longer than the power-off time results in a deflection of the temperature course at the start. Based on analysis of temperature decays correction of temperature is possible. A double-pulse technique is introduced to provide an initial correction of temperature, and fast information about accuracy. Sometimes disturbance with a relatively long response time occurs, probably due to a bad contact between probe, catheter and/or tissue. Thermocouple thermometry proved to be suitable to measure the SAR along a catheter track. This is used to optimize the SAR distribution by patient positioning before treatment. A clinical example illustrates this.

Traceable Measurements of Seebeck Coefficients of Thermoelectric Materials by Using Noble Metal Thermocouples

NASA Astrophysics Data System (ADS)

Haupt, Sebastian; Edler, Frank

2018-06-01

The characterization of thermoelectric materials as reference materials for Seebeck coefficients at the Physikalisch-Technische Bundesanstalt (PTB) is based on the usage of gold/platinum differential thermocouples. In the case of thermoelectric materials containing silicon, the gold/platinum thermocouples are insufficient due to reactions with the silicon when the samples are at higher temperatures. To overcome this limitation and to expand the temperature range for the certification process, platinum/palladium thermocouples were incorporated in the measurement setup. This paper discusses the influence of the different differential thermocouples used for the measurement of the Seebeck coefficients. Results of a comparative investigation of Seebeck coefficient measurements of a metallic and two semiconducting reference materials in the temperature range from 300 K to 870 K are presented.

Red palm oil production by microwave irradiation

NASA Astrophysics Data System (ADS)

Sarah, M.; Widyastuti, S.; Ningsih, D.

2018-02-01

Preliminary study of red palm oil (RPO) production from palm fruitlets by microwave irradiation carried out in domestic microwave oven equipped with thermocouple. The various mass of fruitlets (800, 900 and 1000 g) were heated for 10-18 minutes with 2 minutes interval and microwave power of 400, 560 and 800 Watt respectively. Heated fruitlets were pressed by hydraulic presser to obtain RPO. This study observed heating time parameter was more crucial to RPO quality rather than temperature. Prolonged heating degraded carotenoids in the fruitlets during heating process yielded less carotenoids content in the palm oil. The best time and microwave power combination to produce RPO in this study was 14 minutes and 800 Watt respectively which yielded 11.67% RPO with 1.27% FFA content and carotenoids concentration of 1219.37 ppm. Overall, RPO production by microwave irradiation proceeded faster as compared to conventional process.

A fine-wire thermocouple probe for measurement of stagnation temperatures in real gas hypersonic flows of nitrogen

NASA Technical Reports Server (NTRS)

Hollis, Brian R.; Griffith, Wayland C.; Yanta, William J.

1991-01-01

A fine-wire thermocouple probe was used to determine freestream stagnation temperatures in hypersonic flows. Data were gathered in a N2 blowdown wind tunnel with runtimes of 1-5 s. Tests were made at supply pressures between 30 and 1400 atm and supply temperatures between 700 and 1900 K, with Mach numbers of 14 to 16. An iterative procedure requiring thermocouple data, pilot pressure measurements, and supply conditions was used to determine test cell stagnation temperatures. Probe conduction and radiation losses, as well as real gas behavior of N2, were accounted for during analysis. Temperature measurement error was found to be 5 to 10 percent. A correlation was drawn between thermocouple diameter Reynolds number and temperature recovery ratio. Transient probe behavior was studied and was found to be adequate in temperature gradients up to 1000 K/s.

The effect of ultrasonic post instrumentation on root surface temperature.

PubMed

Huttula, Andrew S; Tordik, Patricia A; Imamura, Glen; Eichmiller, Frederick C; McClanahan, Scott B

2006-11-01

This study measured root surface temperature changes when ultrasonic vibration, with and without irrigation, was applied to cemented endodontic posts. Twenty-six, extracted, single-rooted premolars were randomly divided into two groups. Root lengths were standardized, canals instrumented, obturated, and posts cemented into prepared spaces. Thermocouples were positioned at two locations on the proximal root surfaces. Samples were embedded in plaster and brought to 37 degrees C in a water bath. Posts were ultrasonically vibrated for 4 minutes while continuously measuring temperature. Two-way ANOVA compared effects of water coolant and thermocouple location on temperature change. Root surface temperatures were significantly higher (p < 0.001) when posts were instrumented dry. A trend for higher temperatures was observed at coronal thermocouples of nonirrigated teeth and at apical thermocouples of irrigated teeth (p = 0.057). Irrigation during post removal with ultrasonics had a significant impact on the temperature measured at the external root surface.

Comparative viability of unirradiated and gamma irradiated bacterial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxcy, R.B.

1977-01-01

Gamma radiation injured Escherichia coli, Salmonella typhimurium, and Moraxella sp. were studied under various environmental stresses to determine their fate relative to the parent population. Irradiated cultures formed smaller colonies on surface plates with fewer cells per colony. Unirradiated cultures had a shorter lag phase than irradiated cultures in broth and duration of lag increased as a result of increasing the radiation dose. Repeated irradiation and subculture progressively retarded growth rate. Multiple radiation of highly resistant Moraxella sp. showed radiation injured cells to be more sensitive than uninjured cells. With the three species studied, irradiation raised the lower limits ofmore » growth temperature, increased the sensitivity to freezing and thawing, and increased the susceptibility to lowered water activity. This work indicated that the production of a bizarre, resistant strain of bacteria through recycling in a food processing operation is highly unlikely.« less

Noncatalytic thermocouple coatings produced with chemical vapor deposition for flame temperature measurements.

PubMed

Bahlawane, N; Struckmeier, U; Kasper, T S; Osswald, P

2007-01-01

Chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD) have been employed to develop alumina thin films in order to protect thermocouples from catalytic overheating in flames and to minimize the intrusion presented to the combustion process. Alumina films obtained with a CVD process using AlCl(3) as the precursor are dense, not contaminated, and crystallize in the corundum structure, while MOCVD using Al(acetyl acetone)(3) allows the growth of corundum alumina with improved growth rates. These films, however, present a porous columnar structure and show some carbon contamination. Therefore, coated thermocouples using AlCl(3)-CVD were judged more suitable for flame temperature measurements and were tested in different fuels over a typical range of stoichiometries. Coated thermocouples exhibit satisfactory measurement reproducibility, no temporal drifts, and do not suffer from catalytic effects. Furthermore, their increased radiative heat loss (observed by infrared spectroscopy) allows temperature measurements over a wider range when compared to uncoated thermocouples. A flame with a well-known temperature profile established with laser-based techniques was used to determine the radiative heat loss correction to account for the difference between the apparent temperature measured by the coated thermocouple and the true flame temperature. The validity of the correction term was confirmed with temperature profile measurements for several flames previously studied in different laboratories with laser-based techniques.

Investigating the effects of terahertz radiation on Bacillus subtilis

NASA Astrophysics Data System (ADS)

Giles, Jillian P.; Raitt, Brittany J.; Joseph, Cecil S.; Hines, Mark E.; Giles, Robert H.

2012-03-01

Medical and security sensing applications of Terahertz (THz) imaging are currently being developed. As a result, there is a need to further investigate the effects of THz radiation on biological systems. In this study, a 94 GHz mechanically tuned Gunn Oscillator was used to irradiate Bacillus subtilis at 94 GHz. The bacteria were cultured in trypticase soy broth (TSB) and placed in polystyrene 96 well plates. The samples where irradiated during the exponential growth phase for 1, 2, and 24 hours. Both the experimental and control plates were kept at room temperature (~25°C) and were monitored for the duration of the experiment using thermocouples interfaced with a computer via Labview software. By evaluating the absorption of each well at 600nm immediately before and after irradiation, the population density within each well was assessed. Following this, the metabolic activity of each well was measured after irradiation by adding tetrazolium dye, XTT, to the wells and evaluating the absorption of each well at 490nm after 2 hours of incubation.

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material.

PubMed

Ramu, Ashok T; Mages, Phillip; Zhang, Chong; Imamura, Jeffrey T; Bowers, John E

2012-09-01

The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.

Advances in Thin Film Thermocouple Durability Under High Temperature and Pressure Testing Conditions

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Fralick, Gustave C.; Taylor, Keith F.

1999-01-01

Thin film thermocouples for measuring material surface temperature have been previously demonstrated on several material systems and in various hostile test environments. A well-developed thin film fabrication procedure utilizing shadow masking for patterning the sensors elements had produced thin films with sufficient durability for applications in high temperature and pressure environments that exist in air-breathing and hydrogen-fueled burner rig and engine test facilities. However, while shadow masking had been a reliable method for specimens with flat and gently curved surfaces, it had not been consistently reliable for use on test components with sharp contours. This work reports on the feasibility of utilizing photolithography processing for patterning thin film thermocouples. Because this patterning process required changes in the thin film deposition process from that developed for shadow masking, the effect of these changes on thin film adherence during burner rig testing was evaluated. In addition to the results of changing the patterning method, the effects on thin film adherence of other processes used in the thin film fabrication procedure is also presented.

Metal boot permits fabrication of hermetically sealed splices in metal sheathed instrumentation cables

NASA Technical Reports Server (NTRS)

Chambers, G.

1966-01-01

Metal boot splices hard sheathed instrumentation cables used with high temperature strain gages and thermocouples. Silver brazing the conductors together, hermetically seals the splice. This boot is a highly reliable sealed splice which is equally effective at cryogenic temperatures, high temperatures, nuclear environments, and combinations of the above.

High-Temperature, Thin-Film Ceramic Thermocouples Developed

NASA Technical Reports Server (NTRS)

Sayir, Ali; Blaha, Charles A.; Gonzalez, Jose M.

2005-01-01

To enable long-duration, more distant human and robotic missions for the Vision for Space Exploration, as well as safer, lighter, quieter, and more fuel efficient vehicles for aeronautics and space transportation, NASA is developing instrumentation and material technologies. The high-temperature capabilities of thin-film ceramic thermocouples are being explored at the NASA Glenn Research Center by the Sensors and Electronics Branch and the Ceramics Branch in partnership with Case Western Reserve University (CWRU). Glenn s Sensors and Electronics Branch is developing thin-film sensors for surface measurement of strain, temperature, heat flux, and surface flow in propulsion system research. Glenn s Ceramics Branch, in conjunction with CWRU, is developing structural and functional ceramic technology for aeropropulsion and space propulsion.

Property changes of G347A graphite due to neutron irradiation

DOE PAGES

Campbell, Anne A.; Katoh, Yutai; Snead, Mary A.; ...

2016-08-18

A new, fine-grain nuclear graphite, grade G347A from Tokai Carbon Co., Ltd., has been irradiated in the High Flux Isotope Reactor at Oak Ridge National Laboratory to study the materials property changes that occur when exposed to neutron irradiation at temperatures of interest for Generation-IV nuclear reactor applications. Specimen temperatures ranged from 290°C to 800 °C with a maximum neutron fluence of 40 × 10 25 n/m 2 [E > 0.1 MeV] (~30dpa). Lastly, observed behaviors include: anisotropic behavior of dimensional change in an isotropic graphite, Young's modulus showing parabolic fluence dependence, electrical resistivity increasing at low fluence and additionalmore » increase at high fluence, thermal conductivity rapidly decreasing at low fluence followed by continued degradation, and a similar plateau value of the mean coefficient of thermal expansion for all irradiation temperatures.« less

Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S.J.; Alexander, D.J.; Robertson, J.P.

1997-04-01

Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimensmore » were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.« less

Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

PubMed Central

Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

2009-01-01

Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10−3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

Interstitial Photoacoustic Sensor for the Measurement of Tissue Temperature during Interstitial Laser Phototherapy

PubMed Central

Li, Zhifang; Chen, Haiyu; Zhou, Feifan; Li, Hui; Chen, Wei R.

2015-01-01

Photothermal therapy is an effective means to induce tumor cell death, since tumor tissue is more sensitive to temperature increases than normal tissue. Biological responses depend on tissue temperature; target tissue temperature needs to be precisely measured and controlled to achieve desired thermal effects. In this work, a unique photoacoustic (PA) sensor is proposed for temperature measurement during interstitial laser phototherapy. A continuous-wave laser light and a pulsed laser light, for photothermal irradiation and photoacoustic temperature measurement, respectively, were delivered to the target tissue through a fiber coupler. During laser irradiation, the PA amplitude was measured. The Grüneisen parameter and the bioheat equation were used to determine the temperature in strategic positions in the target tissue. Our results demonstrate that the interstitial PA amplitude is a linear function of temperature in the range of 22 to 55 °C, as confirmed by thermocouple measurement. Furthermore, by choosing appropriate laser parameters, the maximum temperature surrounding the active diffuse fiber tip in tissue can be controlled in the range of 41 to 55 °C. Thus, this sensor could potentially be used for fast, accurate, and convenient three-dimensional temperature measurement, and for real-time feedback and control of interstitial laser phototherapy in cancer treatment. PMID:25756865

Dynamical theory of responsivity and response time of a high temperature superconductor photo-thermoelectrical bolometer

NASA Astrophysics Data System (ADS)

Kaila, M. M.

2002-11-01

Dynamical theory of responsivity and response time for an high temperature superconductor (HTSC) photo-thermoelectrical bolometer is analysed in this paper. There is a thermoelectric feedback (TEF) due to the heat transfer from the sensitive area (HTSC-BiSb thermojunction) towards the cold junction of the thermocouple. This is in addition to the normal electrothermal feedback (ETF) between the detector and the substrate, in a photoelectrical bolometer. The two legs of the thermocouple are connected in a parallel geometry configuration. It is seen that TEF can be used in combination with the ETF to enhance responsivity and response time of the detector.

Investigation of the storage and release of oxygen in a Cu-Pt element of a high-temperature microcombustor

NASA Astrophysics Data System (ADS)

Khaji, Z.; Sturesson, P.; Hjort, K.; Klintberg, L.; Thornell, G.

2014-11-01

A miniature combustor for converting organic samples into CO2 with application in carbon isotopic measurements has been manufactured and evaluated. The combustor was made of High-Temperature Co-fired Ceramic (HTCC) alumina green tapes. The device has a built-in screen printed heater and a temperature sensor made of platinum, co-sintered with the ceramic. A copper oxide oxygen supply was added to the combustor after sintering by in-situ electroplating of copper on the heater pattern followed by thermal oxidation. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Thermal Gravimetric Analysis (TGA) were used to study electroplating, oxidation and the oxide reduction processes. The temperature sensor was calibrated by use of a thermocouple. It demonstrates a temperature coefficient resistance of 4.66×10-3/°C between 32 and 660 °C. The heat characterization was done up to 1000 °C by using IR thermography, and the results were compared with the data from the temperature sensor. Combustion of starch confirmed the feasibility of using copper oxide as the source of oxygen of combustion.

Assessment of tungsten/rhenium thermocouples with metal-carbon eutectic fixed points up to 1500°C

NASA Astrophysics Data System (ADS)

Gotoh, M.

2013-09-01

Four Type A thermocouples and two Type C thermocouples were calibrated at the Au fixed point and Co-C and Pd-C eutectic fixed points. The thermocouples were exposed to 1330 °C for a total of 100 hours. The maximum drift due to the exposure was found to be 4.8 °C. The fixed-point calibration EMF of these thermocouples deviated by less than 0.86% from the temperature specified by the standards ASTM E230-2003 for Type C and GOSTR 8.585-2001 for Type A. The length of one of Type A thermocouples A52 is longer than the others by 150mm. Making use of this provision it was possible to place annealed part of A52 to the temperature gradient part of calibration arrangement every time. Therefore observed aging effect was as low as 0.5 °C compared to the other thermocouples.

Microprocessor-controlled Nd:YAG laser for hyperthermia induction in the RIF-1 tumor.

PubMed

Waldow, S M; Russell, G E; Wallner, P E

1992-01-01

Near-infrared radiation from a Nd:YAG laser at 1,064 nm was used interstitially or superficially to induce hyperthermia in RIF-1 tumors in C3H male mice. A single 600-microns quartz fiber with a 0.5-cm cylindrical diffusor or a weakly diverging microlens at its distal end was used to deliver laser energy to tumors in the hind leg (mean volume = 100 mm3). Two thermocouples were inserted into each tumor. One thermocouple controlled a microprocessor-driven hyperthermia program (maximum output of 3.5 Watts) to maintain the desired temperature. Tumors were exposed to various temperature-time combinations (42-45 degrees C/30 min). Our initial results indicated that excellent temperature control to within 0.2 degrees C of the desired temperature at the feedback thermocouple was achievable during both superficial and interstitial heat treatments. Temperatures at the second thermocouple, however, were found to be lower by as much as 2.3 degrees C (using the cylindrical diffusor) or higher by up to 4.6 degrees C (using the microlens) when compared to the feedback thermocouple temperature. Several correlations were seen between total dose, tumor growth delay, percent skin necrosis, and temperature at the second thermocouple after several superficial and interstitial treatments. Statistically significant improvements in tumor growth delay (at 42 and 45 degrees C) and increased percent skin necrosis at all temperatures were observed after superficial versus interstitial treatment.

Detailed Uncertainty Analysis of the ZEM-3 Measurement System

NASA Technical Reports Server (NTRS)

Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

2014-01-01

The measurement of Seebeck coefficient and electrical resistivity are critical to the investigation of all thermoelectric systems. Therefore, it stands that the measurement uncertainty must be well understood to report ZT values which are accurate and trustworthy. A detailed uncertainty analysis of the ZEM-3 measurement system has been performed. The uncertainty analysis calculates error in the electrical resistivity measurement as a result of sample geometry tolerance, probe geometry tolerance, statistical error, and multi-meter uncertainty. The uncertainty on Seebeck coefficient includes probe wire correction factors, statistical error, multi-meter uncertainty, and most importantly the cold-finger effect. The cold-finger effect plagues all potentiometric (four-probe) Seebeck measurement systems, as heat parasitically transfers through thermocouple probes. The effect leads to an asymmetric over-estimation of the Seebeck coefficient. A thermal finite element analysis allows for quantification of the phenomenon, and provides an estimate on the uncertainty of the Seebeck coefficient. The thermoelectric power factor has been found to have an uncertainty of +9-14 at high temperature and 9 near room temperature.

Comparison of halogen, plasma and LED curing units.

PubMed

Nomoto, Rie; McCabe, John F; Hirano, Susumu

2004-01-01

This study evaluated the characteristics of two kinds of recently developed light-curing unit; plasma arc and blue light emitting diodes (LED), in comparison with a conventional tungsten-halogen light-curing unit. The light intensity and spectral distribution of light from these light-curing units, the temperature rise of the bovine enamel surface and the depth of cure of composites exposed to each unit were investigated. The light intensity and depth of cure were determined according to ISO standards. The spectral distributions of emitted light were measured using a spectro-radiometer. The temperature increase induced by irradiation was measured by using a thermocouple. Generally, light intensities in the range 400-515 nm emitted from the plasma arc were greater than those from other types. Light in the UV-A region was emitted from some plasma arc units. The required irradiation times were six to nine seconds for the plasma arc units and 40 to 60 seconds for the LED units to create a depth of cure equal to that produced by the tungsten-halogen light with 20 seconds of irradiation. The temperature increased by increasing the irradiation time for every light-curing unit. The temperature increases were 15 degrees C to 60 degrees C for plasma arc units, around 15 degrees C for a conventional halogen unit and under 10 degrees C for LED units. Both the plasma arc and LED units required longer irradiation times than those recommended by their respective manufacturers. Clinicians should be aware of potential thermal rise and UV-A hazard when using plasma arc units.

Structural modifications induced by ion irradiation and temperature in boron carbide B4C

NASA Astrophysics Data System (ADS)

Victor, G.; Pipon, Y.; Bérerd, N.; Toulhoat, N.; Moncoffre, N.; Djourelov, N.; Miro, S.; Baillet, J.; Pradeilles, N.; Rapaud, O.; Maître, A.; Gosset, D.

2015-12-01

Already used as neutron absorber in the current French nuclear reactors, boron carbide (B4C) is also considered in the future Sodium Fast Reactors of the next generation (Gen IV). Due to severe irradiation conditions occurring in these reactors, it is of primary importance that this material presents a high structural resistance under irradiation, both in the ballistic and electronic damage regimes. Previous works have shown an important structural resistance of boron carbide even at high neutron fluences. Nevertheless, the structural modification mechanisms due to irradiation are not well understood. Therefore the aim of this paper is to study structural modifications induced in B4C samples in different damage regimes. The boron carbide pellets were shaped and sintered by using spark plasma sintering method. They were then irradiated in several conditions at room temperature or 800 °C, either by favoring the creation of ballistic damage (between 1 and 3 dpa), or by favoring the electronic excitations using 100 MeV swift iodine ions (Se ≈ 15 keV/nm). Ex situ micro-Raman spectroscopy and Doppler broadening of annihilation radiation technique with variable energy slow positrons were coupled to follow the evolution of the B4C structure under irradiation.

High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

NASA Astrophysics Data System (ADS)

Alsagabi, Sultan

The 9Cr-2W ferritic-martensitic steel (i.e. Grade 92 steel) possesses excellent mechanical and thermophysical properties; therefore, it has been considered to suit more challenging applications where high temperature strength and creep-rupture properties are required. The high temperature deformation mechanism was investigated through a set of tensile testing at elevated temperatures. Hence, the threshold stress concept was applied to elucidate the operating high temperature deformation mechanism. It was identified as the high temperature climb of edge dislocations due to the particle-dislocation interactions and the appropriate constitutive equation was developed. In addition, the microstructural evolution at room and elevated temperatures was investigated. For instance, the microstructural evolution under loading was more pronounced and carbide precipitation showed more coarsening tendency. The growth of these carbide precipitates, by removing W and Mo from matrix, significantly deteriorates the solid solution strengthening. The MX type carbonitrides exhibited better coarsening resistance. To better understand the thermal microstructural stability, long tempering schedules up to 1000 hours was conducted at 560, 660 and 760°C after normalizing the steel. Still, the coarsening rate of M23C 6 carbides was higher than the MX-type particles. Moreover, the Laves phase particles were detected after tempering the steel for long periods before they dissolve back into the matrix at high temperature (i.e. 720°C). The influence of the tempering temperature and time was studied for Grade 92 steel via Hollomon-Jaffe parameter. Finally, the irradiation performance of Grade 92 steel was evaluated to examine the feasibility of its eventual reactor use. To that end, Grade 92 steel was irradiated with iron (Fe2+) ions to 10, 50 and 100 dpa at 30 and 500°C. Overall, the irradiated samples showed some irradiation-induced hardening which was more noticeable at 30°C. Additionally, irradiation-induced defect clusters and dislocation loops were observed and the irradiated samples did not show any bubble or void.

Focused ultrasound thermal therapy system with ultrasound image guidance and temperature measurement feedback.

PubMed

Lin, Kao-Han; Young, Sun-Yi; Hsu, Ming-Chuan; Chan, Hsu; Chen, Yung-Yaw; Lin, Win-Li

2008-01-01

In this study, we developed a focused ultrasound (FUS) thermal therapy system with ultrasound image guidance and thermocouple temperature measurement feedback. Hydraulic position devices and computer-controlled servo motors were used to move the FUS transducer to the desired location with the measurement of actual movement by linear scale. The entire system integrated automatic position devices, FUS transducer, power amplifier, ultrasound image system, and thermocouple temperature measurement into a graphical user interface. For the treatment procedure, a thermocouple was implanted into a targeted treatment region in a tissue-mimicking phantom under ultrasound image guidance, and then the acoustic interference pattern formed by image ultrasound beam and low-power FUS beam was employed as image guidance to move the FUS transducer to have its focal zone coincident with the thermocouple tip. The thermocouple temperature rise was used to determine the sonication duration for a suitable thermal lesion as a high power was turned on and ultrasound image was used to capture the thermal lesion formation. For a multiple lesion formation, the FUS transducer was moved under the acoustic interference guidance to a new location and then it sonicated with the same power level and duration. This system was evaluated and the results showed that it could perform two-dimensional motion control to do a two-dimensional thermal therapy with a small localization error 0.5 mm. Through the user interface, the FUS transducer could be moved to heat the target region with the guidance of ultrasound image and acoustic interference pattern. The preliminary phantom experimental results demonstrated that the system could achieve the desired treatment plan satisfactorily.

Multipurpose instrumentation cable provides integral thermocouple circuit

NASA Technical Reports Server (NTRS)

Zellner, G.

1967-01-01

Multipurpose cable with an integral thermocouple circuit measures strain, vibration, pressure, throughout a wide temperature range. This cable reduces bulky and complex circuitry by eliminating separate thermocouples for each transducer.

Thermal effects of the Er:YAG laser on a simulated dental pulp: a quantitative evaluation of the effects of a water spray.

PubMed

Attrill, D C; Davies, R M; King, T A; Dickinson, M R; Blinkhorn, A S

2004-01-01

To quantify the temperature increments in a simulated dental pulp following irradiation with an Er:YAG laser, and to compare those increments when the laser is applied with and without water spray. Two cavities were prepared on either the buccal or lingual aspect of sound extracted teeth using the laser. One cavity was prepared with water spray, the other without and the order of preparation randomised. Identical preparation parameters were used for both cavities. Temperature increments were measured in the pulp chamber using a calibrated thermocouple and a novel pulp simulant. Maximum increments were 4.0 degrees C (water) and 24.7 degrees C (no water). Water was shown to be highly significant in reducing the overall temperature increments in all cases (p<0.001; paired t-test). None of the samples prepared up to a maximum of 135 J cumulative energy prepared with water spray exceeded that threshold at which pulpal damage can be considered to occur. Only 25% of those prepared without water spray remained below this threshold. Extrapolation of the figures suggests probably tolerable limits of continuous laser irradiation with water in excess to 160 J. With the incorporation of small breaks in the continuity of laser irradiation that occur in the in vivo situation, the cumulative energy dose tolerated by the pulp should far exceed these figures. The Er:YAG laser must be used in conjunction with water during cavity preparation. As such it should be considered as an effective tool for clinical use based on predicted pulpal responses to thermal stimuli.

Experimental And Numerical Study Of CMC Leading Edges In Hypersonic Flows

NASA Astrophysics Data System (ADS)

Kuhn, Markus; Esser, Burkard; Gulhan, Ali; Dalenbring, Mats; Cavagna, Luca

2011-05-01

Future transportation concepts aim at high supersonic or hypersonic speeds, where the formerly sharp boundaries between aeronautic and aerospace applications become blurred. One of the major issues involved to high speed flight are extremely high aerothermal loads, which especially appear at the leading edges of the plane’s wings and at sharp edged air intake components of the propulsion system. As classical materials like metals or simple ceramics would thermally and structurally fail here, new materials have to be applied. In this context, lightweight ceramic matrix composites (CMC) seem to be prospective candidates as they are high-temperature resistant and offer low thermal expansion along with high specific strength at elevated temperature levels. A generic leading edge model with a ceramic wing assembly with a sweep back angle of 53° was designed, which allowed for easy leading edge sample integration of different CMC materials. The samples consisted of the materials C/C-SiC (non-oxide), OXIPOL and WHIPOX (both oxide) with a nose radius of 2 mm. In addition, a sharp edged C/C-SiC sample was prepared to investigate the nose radius influence. Overall, 13 thermocouples were installed inside the entire model to measure the temperature evolution at specific locations, whereby 5 thermocouples were placed inside the leading edge sample itself. In addition, non-intrusive techniques were applied for surface temperature measurements: An infrared camera was used to measure the surface temperature distribution and at specific spots, the surface temperature was also measured by pyrometers. Following, the model was investigated in DLR’s arc-heated facility L3K at a total enthalpy of 8.5 MJ/kg, Mach number of 7.8, different angles of attack and varying wing inclination angles. These experiments provide a sound basis for the simulation of aerothermally loaded CMC leading edge structures. Such fluid-structure coupled approaches have been performed by FOI, basing on a modal approach for the conduction model. Results show, that the temperature profiles are correctly depicted dependent on the model’s angle of attack.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ojanen, M.; Hahtela, O. M.; Heinonen, M.

MIKES is developing a measurement set-up for calibrating thermocouples in the temperature range 960 °C - 1500 °C. The calibration method is based on direct comparison of thermocouples and radiation thermometers. We have designed a graphite blackbody comparator cell, which is operated in a horizontal single-zone tube furnace. The cell includes two blackbody cavities for radiation temperature measurements. The cavities have openings on opposite sides of the cell, allowing simultaneous measurement with two radiation thermometers. The design of the comparator allows three thermocouples to be calibrated simultaneously. The thermocouples to be calibrated are inserted in thermometer wells around one ofmore » the measurement cavities. We characterize the blackbody comparator in terms of repeatability, temperature distribution and emissivity. Finally, we validate the uncertainty analysis by comparing calibration results obtained for type B and S thermocouples to the calibration results reported by Technical Research Institute of Sweden (SP), and MIKES. The agreement in the temperature range 1000 °C - 1500 °C is within 0.90 °C, the average deviation being 0.17 °C.« less

High-Sensitivity Temperature Measurement

ERIC Educational Resources Information Center

Leadstone, G. S.

1978-01-01

Describes a method of measuring small temperature differences that amount to a .01K, using an arrangement of a copper-constantan thermocouple, a microamplifier and a galvanometer, as an indirect way of measuring heat energy. (GA)

Integration of thermocouple microelectrode in the scanning electrochemical microscope at variable temperatures: simultaneous temperature and electrochemical imaging and its kinetic studies.

PubMed

Pan, He; Zhang, Hailing; Lai, Junhui; Gu, Xiaoxin; Sun, Jianjun; Tang, Jing; Jin, Tao

2017-03-24

We describe herein a method for the simultaneous measurement of temperature and electrochemical signal with a new type of thermocouple microelectrode. The thermocouple microelectrode can be used not only as a thermometer but also as a scanning electrochemical microscope (SECM) tip in the reaction between tip-generated bromine and a heated Cu sample. The influence of temperature on the SECM imaging process and the related kinetic parameters have been studied, such as kinetic constant and activation energy.

Integration of thermocouple microelectrode in the scanning electrochemical microscope at variable temperatures: simultaneous temperature and electrochemical imaging and its kinetic studies

PubMed Central

Pan, He; Zhang, Hailing; Lai, Junhui; Gu, Xiaoxin; Sun, Jianjun; Tang, Jing; Jin, Tao

2017-01-01

We describe herein a method for the simultaneous measurement of temperature and electrochemical signal with a new type of thermocouple microelectrode. The thermocouple microelectrode can be used not only as a thermometer but also as a scanning electrochemical microscope (SECM) tip in the reaction between tip-generated bromine and a heated Cu sample. The influence of temperature on the SECM imaging process and the related kinetic parameters have been studied, such as kinetic constant and activation energy. PMID:28338002

Amorphization resistance of nano-engineered SiC under heavy ion irradiation

NASA Astrophysics Data System (ADS)

Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; Zhang, Yanwen; Shannon, Steven C.; Weber, William J.

2016-09-01

Silicon carbide (SiC) with a high-density of planar defects (hereafter, 'nano-engineered SiC') and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. It was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due to the local increase in electronic energy loss that enhanced dynamic recovery.

Status of FeCrAl ODS Irradiations in the High Flux Isotope Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Kevin G.; Howard, Richard H.

2016-08-19

FeCrAl oxide-dispersion strengthened (ODS) alloys are an attractive sub-set alloy class of the more global FeCrAl material class for nuclear applications due to their high-temperature steam oxidation resistance and hypothesized enhanced radiation tolerance. A need currently exists to determine the radiation tolerance of these newly developed alloys. To address this need, a preliminary study was conducted using the High Flux Isotope Reactor (HFIR) to irradiate an early generation FeCrAl ODS alloy, 125YF. Preliminary post-irradiation examination (PIE) on these irradiated specimens have shown good radiation tolerance at elevated temperatures (≥330°C) but possible radiation-induced hardening and embrittlement at irradiations of 200°C tomore » a damage level of 1.9 displacement per atom (dpa). Building on this experience, a new series of irradiations are currently being conceptualized. This irradiation series called the FCAD irradiation program will irradiate the latest generation FeCrAl ODS and FeCr ODS alloys to significantly higher doses. These experiments will provide the necessary information to determine the mechanical performance of irradiated FeCrAl ODS alloys at light water reactor and fast reactor conditions.« less

Pulpal Effects of Enamel Ablation With a Microsecond Pulsed λ=9.3-μm CO2 Laser

PubMed Central

Staninec, Michal; Darling, Cynthia L.; Goodis, Harold E.; Pierre, Daniel; Cox, Darren P.; Fan, Kenneth; Larson, Michael; Parisi, Renaldo; Hsu, Dennis; Manesh, Saman K.; Ho, Chi; Hosseini, Mehran; Fried, Daniel

2011-01-01

Background and Objectives In vitro studies have shown that CO2 lasers operating at the highly absorbed 9.3 and 9.6-μm wavelengths with a pulse duration in the range of 10–20-microsecond are well suited for the efficient ablation of enamel and dentin with minimal peripheral thermal damage. Even though these CO2 lasers are highly promising, they have yet to receive FDA approval. Clinical studies are necessary to determine if excessive heat deposition in the tooth may have any detrimental pulpal effects, particularly at higher ablative fluencies. The purpose of this study was to evaluate the pulpal safety of laser irradiation of tooth occlusal surfaces under the conditions required for small conservative preparations confined to enamel. Study Design/Materials and Methods Test subjects requiring removal of third molar teeth were recruited and teeth scheduled for extraction were irradiated using a pulsed CO2 laser at a wavelength of 9.3 μm operating at 25 or 50 Hz using a incident fluence of 20 J/cm2 for a total of 3,000 laser pulses (36 J) for both rates with water cooling. Two control groups were used, one with no treatment and one with a small cut made with a conventional high-speed hand-piece. No anesthetic was used for any of the procedures and tooth vitality was evaluated prior to treatment by heat, cold and electrical testing. Short term effects were observed on teeth extracted within 72 hours after treatment and long term effects were observed on teeth extracted 90 days after treatment. The pulps of the teeth were fixed with formalin immediately after extraction and subjected to histological examination. Additionally, micro-thermocouple measurements were used to estimate the potential temperature rise in the pulp chamber of extracted teeth employing the same irradiation conditions used in vivo. Results Pulpal thermocouple measurements showed the internal temperature rise in the tooth was within safe limits, 3.3±4°C without water cooling versus 1.7±6°C with water-cooling, n=25, P<0.05. None of the control or treatment groups showed any deleterious effects on pulpal tissues and none of the 29 test-subjects felt pain or discomfort after the procedure. Only two test-subjects felt discomfort from “cold sensitivity” during the procedure caused by the water-spray. Conclusion It appears that this CO2 laser can ablate enamel safely without harming the pulp under the rate of energy deposition employed in this study. Lasers Surg. PMID:19347946

Pulpal effects of enamel ablation with a microsecond pulsed lambda = 9.3-microm CO2 laser.

PubMed

Staninec, Michal; Darling, Cynthia L; Goodis, Harold E; Pierre, Daniel; Cox, Darren P; Fan, Kenneth; Larson, Michael; Parisi, Renaldo; Hsu, Dennis; Manesh, Saman K; Ho, Chi; Hosseini, Mehran; Fried, Daniel

2009-04-01

In vitro studies have shown that CO2 lasers operating at the highly absorbed 9.3 and 9.6-microm wavelengths with a pulse duration in the range of 10-20-microsecond are well suited for the efficient ablation of enamel and dentin with minimal peripheral thermal damage. Even though these CO2 lasers are highly promising, they have yet to receive FDA approval. Clinical studies are necessary to determine if excessive heat deposition in the tooth may have any detrimental pulpal effects, particularly at higher ablative fluencies. The purpose of this study was to evaluate the pulpal safety of laser irradiation of tooth occlusal surfaces under the conditions required for small conservative preparations confined to enamel. Test subjects requiring removal of third molar teeth were recruited and teeth scheduled for extraction were irradiated using a pulsed CO2 laser at a wavelength of 9.3 microm operating at 25 or 50 Hz using a incident fluence of 20 J/cm(2) for a total of 3,000 laser pulses (36 J) for both rates with water cooling. Two control groups were used, one with no treatment and one with a small cut made with a conventional high-speed hand-piece. No anesthetic was used for any of the procedures and tooth vitality was evaluated prior to treatment by heat, cold and electrical testing. Short term effects were observed on teeth extracted within 72 hours after treatment and long term effects were observed on teeth extracted 90 days after treatment. The pulps of the teeth were fixed with formalin immediately after extraction and subjected to histological examination. Additionally, micro-thermocouple measurements were used to estimate the potential temperature rise in the pulp chamber of extracted teeth employing the same irradiation conditions used in vivo. Pulpal thermocouple measurements showed the internal temperature rise in the tooth was within safe limits, 3.3+/-1.4 degrees C without water cooling versus 1.7+/-1.6 degrees C with water-cooling, n = 25, P<0.05. None of the control or treatment groups showed any deleterious effects on pulpal tissues and none of the 29 test-subjects felt pain or discomfort after the procedure. Only two test-subjects felt discomfort from "cold sensitivity" during the procedure caused by the water-spray. It appears that this CO2 laser can ablate enamel safely without harming the pulp under the rate of energy deposition employed in this study.

Using electron irradiation to probe iron-based superconductors

NASA Astrophysics Data System (ADS)

Cho, Kyuil; Kończykowski, M.; Teknowijoyo, S.; Tanatar, M. A.; Prozorov, R.

2018-06-01

High-energy electron irradiation at low temperatures is an efficient and controlled way to create vacancy–interstitial Frenkel pairs in a crystal lattice, thereby inducing nonmagnetic point-like scattering centers. In combination with London penetration depth and resistivity measurements, the electron irradiation was used as a phase-sensitive probe to study the superconducting order parameter in iron-based superconductors (FeSCs), lending strong support to sign-changing s ± pairing. Here, we review the key results of the effect of electron irradiation in FeSCs.

Measuring nanowire thermal conductivity at high temperatures

NASA Astrophysics Data System (ADS)

Wang, Xiaomeng; Yang, Juekuan; Xiong, Yucheng; Huang, Baoling; Xu, Terry T.; Li, Deyu; Xu, Dongyan

2018-02-01

This work extends the micro-thermal-bridge method for thermal conductivity measurements of nanowires to high temperatures. The thermal-bridge method, based on a microfabricated device with two side-by-side suspended membranes with integrated platinum resistance heaters/thermometers, has been used to determine thermal conductivity of various nanowires/nanotubes/nanoribbons at relatively low temperatures. However, to date, thermal conductivity characterization of nanowires at temperatures above 600 K has seldom been reported presumably due to several technical difficulties including the instability of the microfabricated thermometers, radiation heat loss, and the effect of the background conductance on the measurement. Here we report on our attempt to address the aforementioned challenges and demonstrate thermal conductivity measurement of boron nanoribbons up to 740 K. To eliminate high temperature resistance instability, the device is first annealed at 1023 K for 5 min in an argon atmosphere. Two radiation shields are installed in the measurement chamber to minimize radiation heat loss from the measurement device to the surroundings; and the temperature of the device at each set point is calibrated by an additional thermocouple directly mounted on the chip carrier. The effect of the background conductance is eliminated by adopting a differential measurement scheme. With all these modifications, we successfully measured the thermal conductivity of boron nanoribbons over a wide temperature range from 27 K to 740 K. The measured thermal conductivity increases monotonically with temperature and reaches a plateau of ~2.5 W m-1 K-1 at approximately 400 K, with no clear signature of Umklapp scattering observed in the whole measurement temperature range.

Attachment of Free Filament Thermocouples for Temperature Measurements on Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Cuy, Michael D.; Wnuk, Stephen P.

1998-01-01

At the NASA Lewis Research Center, a new installation technique utilizing convoluted wire thermocouples (TC's) was developed and proven to produce very good adhesion on CMC's, even in a burner rig environment. Because of their unique convoluted design, such TC's of various types and sizes adhere to flat or curved CMC specimens with no sign of delamination, open circuits, or interactions-even after testing in a Mach 0.3 burner rig to 1200 C (2200 F) for several thermal cycles and at several hours at high temperatures. Large differences in thermal expansion between metal thermocouples and low-expansion materials, such as CMC's, normally generate large stresses in the wires. These stresses cause straight wires to detach, but convoluted wires that are bonded with strips of coating allow bending in the unbonded portion to relieve these expansion stresses.

Processing techniques for correlation of LDA and thermocouple signals

NASA Astrophysics Data System (ADS)

Nina, M. N. R.; Pita, G. P. A.

1986-11-01

A technique was developed to enable the evaluation of the correlation between velocity and temperature, with laser Doppler anemometer (LDA) as the source of velocity signals and fine wire thermocouple as that of flow temperature. The discontinuous nature of LDA signals requires a special technique for correlation, in particular when few seeding particles are present in the flow. The thermocouple signal was analog compensated in frequency and the effect of the value of time constant on the velocity temperature correlation was studied.

Temperature rises during application of Er:YAG laser under different primary dentin thicknesses.

PubMed

Hubbezoglu, Ihsan; Unal, Murat; Zan, Recai; Hurmuzlu, Feridun

2013-05-01

The present study investigated the effects of the Er:YAG laser's different pulse repetition rates on temperature rise under various primary dentin thicknesses. The Er:YAG laser can be used for restorative approaches in clinics and is used to treat dental caries. There are some reports that explain the temperature rise effect of the Er:YAG laser. Recently, the Er:YAG laser has been found to play an important role in temperature rises during the application on dentin. Caries-free primary mandibular molars were prepared to obtain dentin discs with 0.5, 1, 1.5, and 2 mm thicknesses (n=10). These discs were placed between the Teflon mold cylinders of a temperature test apparatus. We preferred three pulse repetition rates of 10, 15, and 20 Hz with an energy density of 12.7 J/cm2 and a 230 μs pulse duration. All dentin discs were irradiated for 30 sec by the Er:YAG laser. Temperature rises were recorded using an L-type thermocouple and universal data loggers/scanners (E-680, Elimko Co., Turkey). Data were analyzed by two-way ANOVA and Tukey tests. Whereas the lowest temperature rise (0.44±0.09 °C) was measured from a 10 Hz pulse repetition rate at a dentin thickness of 2 mm, the highest temperature rise (3.86±0.43 °C) was measured from a 20 Hz pulse repetition rate at a 0.5 mm dentin thickness. Temperature rise did not reach critical value for pulpal injury in any primary dentin thicknesses irradiated by a high repetition rate of the Er:YAG laser.

Safe and consistent method of spot-welding platinum thermocouple wires and foils for high temperature measurements.

PubMed

Orr, G; Roth, M

2012-08-01

A low-voltage (mV) electronically triggered spot welding system for fabricating fine thermocouples and thin sheets used in high-temperature characterization of materials' properties is suggested. The system is based on the capacitance discharge method with a timed trigger for obtaining reliable and consistent welds. In contrast to existing techniques based on employing high voltage DC supplies for charging the capacitor or supplies with positive and negative rails, this method uses a simple, standard dual power supply available at most of the physical laboratories or can be acquired at a low cost. In addition, an efficient and simple method of fabricating non-sticking electrodes that do not contaminate the weld area is suggested and implemented.

Temporary Thermocouple Attachment for Thermal/Vacuum Testing at Non-Extreme Temperatures - Test Results

NASA Technical Reports Server (NTRS)

Wright, Sarah E.; Ungar, Eugene K.

2017-01-01

Post-test examination and data analysis that followed a two week long vacuum test showed that numerous self-stick thermocouples became detached from the test article. The thermocouples were reattached with thermally conductive epoxy and the test was repeated to obtain the required data. Because the thermocouple detachment resulted in significant expense and rework, it was decided to investigate the temporary attachment methods used around NASA and to perform a test to assess their efficacy. The present work describes the testing that was performed in early and mid-2017. The test article and the temporary thermocouple attachment methods tested are described. During the first test, fully half of the thermocouples detached - although the detachment showed subtly in the data for some. The second test was performed to confirm the data from the first test and to investigate the effect of test article and thermocouple grounding. The results of the testing over temperatures ranging from -150 to 200degF are detailed and preliminary recommendations are made for temporary thermocouple attachment methods.

Micro-thermocouple on nano-membrane: thermometer for nanoscale measurements.

PubMed

Balčytis, Armandas; Ryu, Meguya; Juodkazis, Saulius; Morikawa, Junko

2018-04-20

A thermocouple of Au-Ni with only 2.5-μm-wide electrodes on a 30-nm-thick Si 3 N 4 membrane was fabricated by a simple low-resolution electron beam lithography and lift off procedure. The thermocouple is shown to be sensitive to heat generated by laser as well as an electron beam. Nano-thin membrane was used to reach a high spatial resolution of energy deposition and to realise a heat source of sub-1 μm diameter. This was achieved due to a limited generation of secondary electrons, which increase a lateral energy deposition. A low thermal capacitance of the fabricated devices is useful for the real time monitoring of small and fast temperature changes, e.g., due to convection, and can be detected through an optical and mechanical barrier of the nano-thin membrane. Temperature changes up to ~2 × 10 5 K/s can be measured at 10 kHz rate. A simultaneous down-sizing of both, the heat detector and heat source strongly required for creation of thermal microscopy is demonstrated. Peculiarities of Seebeck constant (thermopower) dependence on electron injection into thermocouple are discussed. Modeling of thermal flows on a nano-membrane with presence of a micro-thermocouple was carried out to compare with experimentally measured temporal response.

Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarantopoulou, E., E-mail: esarant@eie.gr; Stefi, A.; Kollia, Z.

Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm⁻²) or vacuum-ultraviolet irradiation (110–180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance inmore » spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.« less

Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.

PubMed

Hindasageri, V; Vedula, R P; Prabhu, S V

2013-02-01

Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient

NASA Astrophysics Data System (ADS)

Hindasageri, V.; Vedula, R. P.; Prabhu, S. V.

2013-02-01

Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

Diagnostic developments for velocity and temperature measurements in uni-element rocket environments

NASA Astrophysics Data System (ADS)

Philippart, Kenneth D.

1995-08-01

Velocity and temperature measurements were taken within a uni-element rocket combustion chamber for hydrogen-oxygen propellants using laser Doppler velocimetry, thermocouples, and a thermocouple-based temperature rake developed for this effort. Velocity and turbulence profiles were obtained for firings with a gaseous oxygen (GO2)/gaseous hydrogen (GH2) coaxial shear injector at axial locations of 1.6 mm (0.063 in.), 6.4 mm (0.25 in.), 12.7 mm (0.5 in.), 25.4 mm (1 in.) and 50.8 mm (2 in.). Aluminum oxide particles of various sizes seeded the flow in an attempt to explain the discrepancies. While cold-flow simulations were promising, hot-fire results for the various particles were virtually identical and still lower than earlier data. The hot-firings were self-consistent and question the reproducibility of the previous data. Velocity measurements were made closer to the injector than the preceding work. Asymmetries were noted in all profiles. The shear layer displayed high turbulence levels. The central flow near the injector resembled turbulent pipe flow. Recirculation zones existed at the chamber walls and became smaller as the flow evolved downstream. The combusting flow region expanded with increasing axial distance. A thermocouple-instrumented coaxial injector was fired with GO2/GH2 propellants. The injector exit plane boundary conditions were determined. The feasibility of a thermocouple-based temperature rake was established. Tests at three axial positions for air/GM2 firings revealed asymmetric profiles. Temperatures increased with increasing axial distance.

Development of re-crystallized W-1.1%TiC with enhanced room-temperature ductility and radiation performance

NASA Astrophysics Data System (ADS)

Kurishita, H.; Matsuo, S.; Arakawa, H.; Sakamoto, T.; Kobayashi, S.; Nakai, K.; Takida, T.; Kato, M.; Kawai, M.; Yoshida, N.

2010-03-01

Ultra-fine grained (UFG) W-TiC compacts fabricated by powder metallurgical methods utilizing mechanical alloying (MA) are very promising for use in irradiation environments. However, the assurance of room-temperature ductility and enhancement in surface resistances to low-energy hydrogen irradiation are unsettled issues. As an approach to solution to these, microstructural modification by hot plastic working has been applied to UFG W-TiC processed by MA in a purified Ar or H 2 atmosphere and hot isostatic pressing (HIP). Hot plastically worked compacts have been subjected to 3-point bend tests at room temperature and TEM microstructural examinations. It is found that the microstructural modification allows us to convert UFG W-1.1%TiC to compacts exhibiting a very high fracture strength and appreciable ductility at room temperature. The compacts of W-1.1%TiC/Ar (MA atmosphere: Ar) and W-1.1%TiC/H 2 (MA atmosphere: H 2) exhibit re-crystallized structures with approximately 0.5 and 1.5 μm in grain size, respectively. It is shown that the enhancement of fracture resistance by microstructural modifications is attributed to significant strengthening of weak grain boundaries in the re-crystallized state. As a result the modified compacts exhibit superior surface resistance to low-energy deuteron irradiation.

Device for self-verifying temperature measurement and control

DOEpatents

Watkins, Arthur D.; Cannon, Collins P.; Tolle, Charles R.

2004-08-03

A measuring instrument includes a first temperature sensor, a second temperature sensor and circuitry. The first and second temperature sensors each generate a signal indicative of the temperature of a medium being detected. The circuitry is configured to activate verification of temperature being sensed with the first sensor. According to one construction, the first temperature sensor comprises at least one thermocouple temperature sensor and the second temperature sensor comprises an optical temperature sensor, each sensor measuring temperature over the same range of temperature, but using a different physical phenomena. Also according to one construction, the circuitry comprises a computer configured to detect failure of one of the thermocouples by comparing temperature of the optical temperature sensor with each of the thermocouple temperature sensors. Even further, an output control signal is generated via a fuzzy inference machine and control apparatus.

Device and method for self-verifying temperature measurement and control

DOEpatents

Watkins, Arthur D.; Cannon, Collins P.; Tolle, Charles R.

2002-10-29

A measuring instrument includes a first temperature sensor, a second temperature sensor and circuitry. The first and second temperature sensors each generate a signal indicative of the temperature of a medium being detected. The circuitry is configured to activate verification of temperature being sensed with the first sensor. According to one construction, the first temperature sensor comprises at least one thermocouple temperature sensor and the second temperature sensor comprises an optical temperature sensor, each sensor measuring temperature over the same range of temperature, but using a different physical phenomena. Also according to one construction, the circuitry comprises a computer configured to detect failure of one of the thermocouples by comparing temperature of the optical temperature sensor with each of the thermocouple temperature sensors. Even further, an output control signal is generated via a fuzzy inference machine and control apparatus.

Laser welded versus resistance spot welded bone implants: analysis of the thermal increase and strength.

PubMed

Fornaini, Carlo; Meleti, Marco; Bonanini, Mauro; Lagori, Giuseppe; Vescovi, Paolo; Merigo, Elisabetta; Nammour, Samir

2014-01-01

The first aim of this "ex vivo split mouth" study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant). Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength.

Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

PubMed Central

Fornaini, Carlo; Meleti, Marco; Bonanini, Mauro; Lagori, Giuseppe; Vescovi, Paolo; Merigo, Elisabetta; Nammour, Samir

2014-01-01

Introduction. The first aim of this “ex vivo split mouth” study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Materials and Methods. Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. Results. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant). Conclusion. Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength. PMID:25110731

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, Anne A.; Katoh, Yutai; Snead, Mary A.

A new, fine-grain nuclear graphite, grade G347A from Tokai Carbon Co., Ltd., has been irradiated in the High Flux Isotope Reactor at Oak Ridge National Laboratory to study the materials property changes that occur when exposed to neutron irradiation at temperatures of interest for Generation-IV nuclear reactor applications. Specimen temperatures ranged from 290°C to 800 °C with a maximum neutron fluence of 40 × 10 25 n/m 2 [E > 0.1 MeV] (~30dpa). Lastly, observed behaviors include: anisotropic behavior of dimensional change in an isotropic graphite, Young's modulus showing parabolic fluence dependence, electrical resistivity increasing at low fluence and additionalmore » increase at high fluence, thermal conductivity rapidly decreasing at low fluence followed by continued degradation, and a similar plateau value of the mean coefficient of thermal expansion for all irradiation temperatures.« less

Effect of 50 MeV Li3 + irradiation on structural and electrical properties of Mn-doped ZnO

NASA Astrophysics Data System (ADS)

Neogi, S. K.; Chattopadhyay, S.; Banerjee, Aritra; Bandyopadhyay, S.; Sarkar, A.; Kumar, Ravi

2011-05-01

The present work aims to study the effect of ion irradiation on structural and electrical properties and their correlation with the defects in the Zn1 - xMnxO-type system. Zn1 - xMnxO (x = 0.02, 0.04) samples have been synthesized by the solid-state reaction method and have been irradiated with 50 MeV Li3 + ions. The concomitant changes have been probed by x-ray diffraction (XRD), temperature-dependent electrical resistivity and positron annihilation lifetime (PAL) spectroscopy. The XRD result shows a single-phase wurtzite structure for Zn0.98Mn0.02O, whereas for the Zn0.96Mn0.04O sample an impurity phase has been found, apart from the usual peaks of ZnO. Ion irradiation removes this impurity peak. The grain size of the samples is found to be uniform. For Zn0.98Mn0.02O, the observed sharp decrease in room temperature resistivity (ρRT) with irradiation is consistent with the lowering of the full width at half maximum of the XRD peaks. However, for Zn0.96Mn0.04O, ρRT decreases for the initial fluence but increases for a further increase in fluence. All the irradiated Zn0.98Mn0.02O samples show a metal-semiconductor transition in temperature-dependent resistivity measurements at low temperature. But all the irradiated Zn0.96Mn0.04O samples show a semiconducting nature in the whole range of temperatures. Results of room temperature resistivity, XRD and PAL measurements are consistent with each other.

Effect of 50 MeV Li3+ irradiation on structural and electrical properties of Mn-doped ZnO.

PubMed

Neogi, S K; Chattopadhyay, S; Banerjee, Aritra; Bandyopadhyay, S; Sarkar, A; Kumar, Ravi

2011-05-25

The present work aims to study the effect of ion irradiation on structural and electrical properties and their correlation with the defects in the Zn(1 - x)Mn(x)O-type system. Zn(1 - x)Mn(x)O (x = 0.02, 0.04) samples have been synthesized by the solid-state reaction method and have been irradiated with 50 MeV Li(3+) ions. The concomitant changes have been probed by x-ray diffraction (XRD), temperature-dependent electrical resistivity and positron annihilation lifetime (PAL) spectroscopy. The XRD result shows a single-phase wurtzite structure for Zn(0.98)Mn(0.02)O, whereas for the Zn(0.96)Mn(0.04)O sample an impurity phase has been found, apart from the usual peaks of ZnO. Ion irradiation removes this impurity peak. The grain size of the samples is found to be uniform. For Zn(0.98)Mn(0.02)O, the observed sharp decrease in room temperature resistivity (ρ(RT)) with irradiation is consistent with the lowering of the full width at half maximum of the XRD peaks. However, for Zn(0.96)Mn(0.04)O, ρ(RT) decreases for the initial fluence but increases for a further increase in fluence. All the irradiated Zn(0.98)Mn(0.02)O samples show a metal-semiconductor transition in temperature-dependent resistivity measurements at low temperature. But all the irradiated Zn(0.96)Mn(0.04)O samples show a semiconducting nature in the whole range of temperatures. Results of room temperature resistivity, XRD and PAL measurements are consistent with each other.

Argonne Bubble Experiment Thermal Model Development II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buechler, Cynthia Eileen

2016-07-01

This report describes the continuation of the work reported in “Argonne Bubble Experiment Thermal Model Development”. The experiment was performed at Argonne National Laboratory (ANL) in 2014. A rastered 35 MeV electron beam deposited power in a solution of uranyl sulfate, generating heat and radiolytic gas bubbles. Irradiations were performed at three beam power levels, 6, 12 and 15 kW. Solution temperatures were measured by thermocouples, and gas bubble behavior was observed. This report will describe the Computational Fluid Dynamics (CFD) model that was developed to calculate the temperatures and gas volume fractions in the solution vessel during the irradiations.more » The previous report described an initial analysis performed on a geometry that had not been updated to reflect the as-built solution vessel. Here, the as-built geometry is used. Monte-Carlo N-Particle (MCNP) calculations were performed on the updated geometry, and these results were used to define the power deposition profile for the CFD analyses, which were performed using Fluent, Ver. 16.2. CFD analyses were performed for the 12 and 15 kW irradiations, and further improvements to the model were incorporated, including the consideration of power deposition in nearby vessel components, gas mixture composition, and bubble size distribution. The temperature results of the CFD calculations are compared to experimental measurements.« less

Method of fission heat flux determination from experimental data

DOEpatents

Paxton, Frank A.

1999-01-01

A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.

Multiwire thermocouples: Frequency response

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1994-01-01

Experimental measurements are made with a novel two wire thermocouple. Signals from two wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the two wire thermocouple requires no compensation for omega less than or equal to 2 omega(sub 1) where omega is the natural frequency of the smaller wire. A compensation factor is recommended for larger frequencies omega greater than 2 omega(sub 1). Theory and experimental measurements are compared with a novel three wire thermocouple. Signals from three wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three wire thermocouple requires no compensation for omega less than or equal to 5 omega(sub 1) where omega (sub 1) is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter. Measurements are recorded for multiwire thermocouples consisting of either two or three wires of unequal diameters. Signals from the multiwire probe are recorded for a reversing gas flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the multiwire thermocouple requires no compensation provided omega/omega(sub 1) is less than 2.3 for two wires or omega/omega(sub 1) is less than 3.6 for three wires where omega(sub 1) is the natural frequency of the smaller wire based on the maximum gas velocity. The latter results were possible provided Fourier transformed data were used and knowledge of the gas velocity is available.

Beyond "fire temperatures": calibrating thermocouple probes and modeling their response to surface fires in hardwood fuels

Treesearch

Anthony S. Bova; Matthew B. Dickinson

2008-01-01

The maximum temperatures of thermocouples, temperature-sensitive paints, and calorimeters exposed to flames in wildland fires are often called "fire temperatures" but are determined as much by the properties and deployment of the measurement devices as by the fires themselves. Rather than report device temperatures that are not generally comparable among...

Investigation of factors affecting the heater wire method of calibrating fine wire thermocouples

NASA Technical Reports Server (NTRS)

Keshock, E. G.

1972-01-01

An analytical investigation was made of a transient method of calibrating fine wire thermocouples. The system consisted of a 10 mil diameter standard thermocouple (Pt, Pt-13% Rh) and an 0.8 mil diameter chromel-alumel thermocouple attached to a 20 mil diameter electrically heated platinum wire. The calibration procedure consisted of electrically heating the wire to approximately 2500 F within about a seven-second period in an environment approximating atmospheric conditions at 120,000 feet. Rapid periodic readout of the standard and fine wire thermocouple signals permitted a comparison of the two temperature indications. An analysis was performed which indicated that the temperature distortion at the heater wire produced by the thermocouple junctions appears to be of negligible magnitude. Consequently, the calibration technique appears to be basically sound, although several practical changes which appear desirable are presented and discussed. Additional investigation is warranted to evaluate radiation effects and transient response characteristics.

A comparison between internal and surface temperature measurement techniques during phacoemulsification cataract surgery: thermocamera versus thermocouple.

PubMed

Innocenti, B; Diciotti, S; Bocchi, L; Mencucci, R; Corvi, A

2008-01-01

Corneal and scleral burns, one of the main complications that can occur during a cataract operation, are produced by overheating due to the use of the phacoemulsifier. The temperature of the anterior chamber of the eye can be measured both invasively using thermocouples and non-invasively, but only superficially, using a thermocamera. To compare the measures obtained from both techniques an in vitro experimental analysis was conducted on pigs' eyes. During a simulated phacoemulsification cataract operation both the surface temperature with a thermocamera and the temperature inside the anterior chamber with a thermocouple were recorded. For each procedure, the maximum temperature values measured by each technique were compared. The results of this research show that the difference between the maximum values measured with the two techniques is on average 0.5 degrees C. It is possible to employ a thermocamera technique instead of a thermocouple technique to provide an indication of the temperature inside the anterior chamber.

Evaluation of defect formation in helium irradiated Y2O3 doped W-Ti alloys by positron annihilation and nanoindentation

NASA Astrophysics Data System (ADS)

Richter, Asta; Anwand, Wolfgang; Chen, Chun-Liang; Böttger, Roman

2017-10-01

Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 × 1015 cm-2 for a series of samples both at room temperature and at 600 °C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 °C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 °C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy.

Amorphization resistance of nano-engineered SiC under heavy ion irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou

Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due tomore » the local increase in electronic energy loss that enhanced dynamic recovery.« less

Amorphization resistance of nano-engineered SiC under heavy ion irradiation

DOE PAGES

Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; ...

2016-06-19

Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due tomore » the local increase in electronic energy loss that enhanced dynamic recovery.« less

Recent advances in the characterization of high temperature industrial materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meadowcroft, D.B.; Tomkings, A.B.

1995-12-31

This paper reviews several techniques under development or recently commercialized which aid the characterization of high temperature plant components when carrying out lifetime predictions. Temperature measurements are frequently limited because of the limited lifetime and cost of thermocouples in aggressive environments and three alternative methods of assessing the ``average effective`` temperature of a component being evaluated by the authors are described steam side oxide thickness (specifically for ferritic superheater tubes), copper gold diffusion couples (``PETIT``), and the measurement of ferrite in duplex steels (``FEROPLUG``). Advances are described which have been made recently in the measurement techniques available for making plantmore » measurements on components to reduce the time needed for significant values of wastage rates to be established. In addition on-line high, temperature corrosion monitors are coming available which allow wastage rates to be assessed over periods of hours or days. These involve electrical resistance or electrochemical techniques. Finally the use of thin layer activation by a radioactive isotope is highlighted which enables the wastage of components to be assessed remotely without direct contact. Whilst available for a long time for laboratory and pilot plant studies, the authors are actively concerned with introducing the technique into operational boiler plant.« less

Complexity and Challenges in Noncontact High Temperature Measurements in Microwave-Assisted Catalytic Reactors

PubMed Central

2017-01-01

The complexity and challenges in noncontact temperature measurements inside microwave-heated catalytic reactors are presented in this paper. A custom-designed microwave cavity has been used to focus the microwave field on the catalyst and enable monitoring of the temperature field in 2D. A methodology to study the temperature distribution in the catalytic bed by using a thermal camera in combination with a thermocouple for a heterogeneous catalytic reaction (methane dry reforming) under microwave heating has been demonstrated. The effects of various variables that affect the accuracy of temperature recordings are discussed in detail. The necessity of having at least one contact sensor, such as a thermocouple, or some other microwave transparent sensor, is recommended to keep track of the temperature changes occurring in the catalytic bed during the reaction under microwave heating. PMID:29170599

Method and apparatus for measuring temperatures in fabrics and flexible thermal insulations

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor)

1995-01-01

A temperature sensor uses a type R thermocouple wire element in a ceramic sheath to sense temperatures up to 3,200 deg F., and is particularly suitable for flexible insulations. The sensor includes a thermocouple wire embedded in a sheath having two sections disposed at right angles to each other. The junction of the thermocouple is located at one end of one of the sections and the lead wires extend from the other section. The section which includes the junction is secured to a flexible surface with ceramic cement.

Toward increased reliability in the electric power industry: direct temperature measurement in transformers using fiber optic sensors

NASA Astrophysics Data System (ADS)

McDonald, Greg

1998-09-01

Optimal loading, prevention of catastrophic failures and reduced maintenance costs are some of the benefits of accurate determination of hot spot winding temperatures in medium and high power transformers. Temperature estimates obtained using current theoretical models are not always accurate. Traditional technology (IR, thermocouples...) are unsuitable or inadequate for direct measurement. Nortech fiber-optic temperature sensors offer EMI immunity and chemical resistance and are a proven solution to the problem. The Nortech sensor's measurement principle is based on variations in the spectral absorption of a fiber-mounted semiconductor chip and probes are interchangeable with no need for recalibration. Total length of probe + extension can be up to several hundred meters allowing system electronics to be located in the control room or mounted in the transformer instrumentation cabinet. All of the sensor materials withstand temperatures up to 250 degree(s)C and have demonstrated excellent resistance to the harsh transformer environment (hot oil, kerosene). Thorough study of the problem and industry collaboration in testing and installation allows Nortech to identify and meet the need for durable probes, leak-proof feedthroughs, standard computer interfaces and measurement software. Refined probe technology, the method's simplicity and reliable calibration are all assets that should lead to growing acceptance of this type of direct measuring in the electric power industry.

Microwave zero-resistance states in a bilayer electron system.

PubMed

Wiedmann, S; Gusev, G M; Raichev, O E; Bakarov, A K; Portal, J C

2010-07-09

Magnetotransport measurements on a high-mobility electron bilayer system formed in a wide GaAs quantum well reveal vanishing dissipative resistance under continuous microwave irradiation. Profound zero-resistance states (ZRS) appear even in the presence of additional intersubband scattering of electrons. We study the dependence of photoresistance on frequency, microwave power, and temperature. Experimental results are compared with a theory demonstrating that the conditions for absolute negative resistivity correlate with the appearance of ZRS.

High-Precision Temperature Control of a Crystal Growth Furnace at 1,500 C

NASA Technical Reports Server (NTRS)

Stenzel, Ch.; Hess, A.; Croell, A.; Breuer, D.; Sauermann, H.

2012-01-01

For crystal growth of semiconductor materials a short-term temperature stability of 0.1 C at 1500 C is one of the essential parameters to be addressed for achieving high-quality crystals. Hence, for temperature monitoring and control with high precision in a floating zone furnace two sets of thermo-sensors, type B thermocouples and optical fibre thermometers, have been implemented and successfully operated in the furnace for more than 2000 h. The optical fibre thermometers consist of an optical system made of sapphire (two fibres plus a prism in between for deflection) and transmit the infra-red radiation of the heater to the outside of the hot core of the furnace for pyrometric temperature measurement. A dedicated control algorithm has been set up which controlled the power settings to the individual heaters. Both sensor types showed no degradation after this period and yielded a short-term stability at 1200 C of 0.05 C (optical fibre thermometers), respectively 0.08 C (thermocouples).

Laser induced heating of coated carbon steel sheets: Consideration of melting and Marangoni flow

NASA Astrophysics Data System (ADS)

Shuja, S. Z.; Yilbas, B. S.

2013-04-01

Laser induced melting of coated carbon steel workpiece is simulated. The coating materials include tungsten carbide, alumina, and boron are incorporated in the simulations. The coating thickness is kept constant at 7.5 μm in the analysis. The enthalpy porosity method is used to account for the phase change in the irradiated region. The study is extended to include the influence of laser intensity transverse mode pattern (β) on the resulting melting characteristics. It is found that peak temperature predicted at the surface is higher for alumina and boron coatings than that of tungsten carbide coating. The influence of the laser intensity transverse mode pattern on the melting characteristics is considerable. Surface temperature predicted agrees with the thermocouple data.

Setup for irradiation and characterization of materials and Si particle detectors at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Väyrynen, S.; Pusa, P.; Sane, P.; Tikkanen, P.; Räisänen, J.; Kuitunen, K.; Tuomisto, F.; Härkönen, J.; Kassamakov, I.; Tuominen, E.; Tuovinen, E.

2007-03-01

A novel facility for proton irradiation with sample cryocooling has been developed at the Accelerator Laboratory of Helsinki University (equipped with a 5 MV tandem accelerator). The setup enables unique experiments to be carried out within the temperature range of 10-300 K. The setup has been constructed for "on-line" studies of vacancies with positron annihilation spectroscopy (PAS) including the option for optical ionization of the vacancies, and for current-voltage ( IV) measurements of irradiated silicon particle detectors. The setup is described in detail and typical performance characteristics are provided. The facility functionality was tested by performing PAS experiments with high-resistivity silicon and by IV measurements for two types of irradiated silicon particle detectors.

Adiabatic Compression in a Fire Syringe.

ERIC Educational Resources Information Center

Hayn, Carl H.; Baird, Scott C.

1985-01-01

Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)

Low-Cost Thermocouple Signal-Conditioning Module

ERIC Educational Resources Information Center

Lenzi, Marcelo K.; Silva, Fabricio M.; Lima, Enrique L.; Pinto, Jose Carlos; Cunningham, Michael F.

2005-01-01

It is well known that reaction rates and physical properties of any substance depend on the temperature. Therefore, an accurate temperature measurement is a key factor for successful activities both in chemical laboratories and industrial plants. Although plenty of sensors can be adopted for temperature measurements, thermocouples are the most…

Simple, Inexpensive Attainment and Measurement of Very High Cooling and Warming Rates✰

PubMed Central

Kleinhans, F.W.; Seki, Shinsuke; Mazur, Peter

2010-01-01

We have developed a simple, inexpensive system (< $300 US) for measuring cooling and warming rates of small (~ 0.1 μl) aqueous samples at rates as high as 105 °C/min. The measurement system itself, can track rates approaching one million °C/min. For temperature sensing, a Type T thermocouple with 50 μm wire was used. The thermocouple output voltage was read with an inexpensive USB based digital oscilloscope interfaced to a laptop computer, and the raw data were processed with MS Excel. PMID:20599881

Impact of neutron irradiation on mechanical performance of FeCrAl alloy laser-beam weldments

NASA Astrophysics Data System (ADS)

Gussev, M. N.; Cakmak, E.; Field, K. G.

2018-06-01

Oxidation-resistant iron-chromium-aluminum (FeCrAl) alloys demonstrate better performance in Loss-of-Coolant Accidents, compared with austenitic- and zirconium-based alloys. However, further deployment of FeCrAl-based materials requires detailed characterization of their performance under irradiation; moreover, since welding is one of the key operations in fabrication of light water reactor fuel cladding, FeCrAl alloy weldment performance and properties also should be determined prior to and after irradiation. Here, advanced C35M alloy (Fe-13%Cr-5%Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions were characterized after neutron irradiation in Oak Ridge National Laboratory's High Flux Isotope Reactor at 1.8-1.9 dpa in a temperature range of 195-559 °C. Specimen sets included as-received (AR) materials and specimens after controlled laser-beam welding. Tensile tests with digital image correlation (DIC), scanning electron microscopy-electron back scatter diffraction analysis, fractography, and x-ray tomography analysis were performed. DIC allowed for investigating local yield stress in the weldments, deformation hardening behavior, and plastic anisotropy. Both AR and welded material revealed a high degree of radiation-induced hardening for low-temperature irradiation; however, irradiation at high-temperatures (i.e., 559 °C) had little overall effect on the mechanical performance.

Analysis of a Pneumatic Probe for Measuring Exhaust-Gas Temperatures with Some Preliminary Experimental Results

NASA Technical Reports Server (NTRS)

Scadron, Marvin D.

1952-01-01

A pneumatic probe based on continuity of mass flow through two restrictions separated by a cooling chamber was constructed to measure gas temperature at and beyond the limit of thermocouples. This probe consisted of a subsonic flat-plate orifice for the first restriction and a sonic-flow converging-diverging nozzle for the second restriction. The effect of variation in gas constants on the calibration is examined for common engine-exhaust gases. A high-temperature wind tunnel that allowed calibration of the probe at temperatures up to 2000 deg R and. Mach numbers up to 0.8 is described. Agreement to better than 30 deg R between pneumatic probe indication and the indication of a rake of radiation shielded thermocouples indicates that extrapolation of the calibration to higher temperatures is possible with fair accuracy

Some Effects of Exposure to Exhaust-gas Streams on Emittance and Thermoelectric Power of Bare-wire Platinum Rhodium - Platinum Thermocouples

NASA Technical Reports Server (NTRS)

Glawe, George E; Shepard, Charles E

1954-01-01

Thermocouples were exposed to exhaust gases from the combustion of propane, 72-octane gasoline, and JP-4 fuel. Exposure increased the emissivity of the thermocouple wire, which increased its radiation error. Two methods are presented for determining the emittance of the wires. The emissivity of a clean platinum rhodium-platinum thermocouple was approximately 0.2 in the temperature range investigated, while the emittance of an exposed thermocouple coated with exhaust residue was about 0.5. The exposure caused negligible change in the thermoelectric power of the thermocouples.

Modern Thermocouple Experiment.

ERIC Educational Resources Information Center

Chang, K. N.; And Others

1978-01-01

Describes a thermocouple circuit used to measure Joule heating as well as Peltier heating and cooling for a copper-Constantan metallic junction. Shows how the Seebeck effect from a thermocouple can monitor the temperature condition of a junction with regard to input power and Peltier effect. (Author/GA)

Thermal and Irradiation Creep Behavior of a Titanium Aluminide in Advanced Nuclear Plant Environments

NASA Astrophysics Data System (ADS)

Magnusson, Per; Chen, Jiachao; Hoffelner, Wolfgang

2009-12-01

Titanium aluminides are well-accepted elevated temperature materials. In conventional applications, their poor oxidation resistance limits the maximum operating temperature. Advanced reactors operate in nonoxidizing environments. This could enlarge the applicability of these materials to higher temperatures. The behavior of a cast gamma-alpha-2 TiAl was investigated under thermal and irradiation conditions. Irradiation creep was studied in beam using helium implantation. Dog-bone samples of dimensions 10 × 2 × 0.2 mm3 were investigated in a temperature range of 300 °C to 500 °C under irradiation, and significant creep strains were detected. At temperatures above 500 °C, thermal creep becomes the predominant mechanism. Thermal creep was investigated at temperatures up to 900 °C without irradiation with samples of the same geometry. The results are compared with other materials considered for advanced fission applications. These are a ferritic oxide-dispersion-strengthened material (PM2000) and the nickel-base superalloy IN617. A better thermal creep behavior than IN617 was found in the entire temperature range. Up to 900 °C, the expected 104 hour stress rupture properties exceeded even those of the ODS alloy. The irradiation creep performance of the titanium aluminide was comparable with the ODS steels. For IN617, no irradiation creep experiments were performed due to the expected low irradiation resistance (swelling, helium embrittlement) of nickel-base alloys.

Preparation of a Phosphor, ZnS:Cupric.

ERIC Educational Resources Information Center

Suib, Steven L.; Tanaka, John

1984-01-01

Background information (including optical properties of inorganic materials) and procedures are provided for an experiment which introduces students to preparation of a doped semiconductor; phosphorescence; gettering procedures; reducing atmospheres; and use of a high-temperature furnace with associated thermocouples, temperature controllers, and…

Apparatus Tests Thermocouples For Seebeck Inhomogeneity

NASA Technical Reports Server (NTRS)

Burkett, Cecil G., Jr.; Bauserman, Willard A., Jr.; West, James W.

1995-01-01

Automated apparatus reveals sources of error not revealed in calibration. Computer-controlled apparatus detects and measures Seebeck inhomogeneities in sheathed thermocouples. Measures thermocouple output voltage as function of position of probe along sharp gradient of temperature. Abnormal variations in voltage-versus-position data indicative of Seebeck inhomogeneities. Prototype for development of standard method and equipment for routine acceptance/rejection testing of sheathed thermocouples in industrial and research laboratories.

Self-Validating Thermocouple

NASA Technical Reports Server (NTRS)

Perotti, Jose M. (Inventor); Mata, Carlos T. (Inventor); Santiago, Josephine B. (Inventor); Vokrot, Peter (Inventor); Zavala, Carlos E. (Inventor); Burns, Bradley M. (Inventor)

2010-01-01

Self-Validating Thermocouple (SVT) Systems capable of detecting sensor probe open circuits, short circuits, and unnoticeable faults such as a probe debonding and probe degradation are useful in the measurement of temperatures. SVT Systems provide such capabilities by incorporating a heating or excitation element into the measuring junction of the thermocouple. By heating the measuring junction and observing the decay time for the detected DC voltage signal, it is possible to indicate whether the thermocouple is bonded or debonded. A change in the thermal transfer function of the thermocouple system causes a change in the rise and decay times of the thermocouple output. Incorporation of the excitation element does not interfere with normal thermocouple operation, thus further allowing traditional validation procedures as well.

Irradiation qualification testing of SNAP-10A components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesavage, A. J.

1964-02-04

Selected SNAP 10A components were irradiated to about 10{sup14} nvt and 5{times} 10{sup 7} r at an average temperature of 136{degrees}F in a nominal vacuum of 2 {times} 10{sup {minus}5} torr. The components were operated periodically and the electrical characteristics recorded. Pre-irradiationand post-irradiation tests were conducted. Catastropic degradation occurred only in the low-level neutron detection system and about 1.5 {times} 10{sup 13} nvt and in the high-level neutron power supply at about 6{times} 10{sup 12} nvt. Marginal degradation occurred in the fusistors and in the silicone rubber insert material in connectors. The relays, low-voltage trip devices, expansion compensator position demodulator,more » resistance thermometer sensor and bridge, and the gamma detection system opearted within their respective specifications during and after irradiation. The insulation resistance of all components was adeqauate during and after irradiation.« less

In situ resistivity measurements of RAFM base alloys at cryogenic temperatures: The effect of proton irradiation

NASA Astrophysics Data System (ADS)

Gómez-Ferrer, B.; Vila, R.; Jiménez-Rey, D.; Ortiz, C. J.; Mota, F.; García, J. M.; Rodríguez, A.

2014-04-01

A four-probe technique for measurement of electrical resistance on low-temperature ion-irradiated metallic sheets is described. The design, temperature control system, preparation method of samples and the resistivity measurements are described in detail. The resistivity recovery (RR) curve has been measured on a Fe-5%Cr model alloy irradiated with 5 MeV protons. The procedure to obtain the RR derivative curve is outlined and experimental errors are identified and quantified. Special care has been taken to use a sample with very low impurity content and low dislocation density (1.2 × 108 cm-2). Thus, effects in recovery spectrum of the Fe-5%Cr alloy are only due to the presence of Cr and irradiation defects, which will be mainly Frenkel Pairs (FPs) given that the mean energy of the Primary Knock-on Atoms (PKA) is close to 0.35 keV. The results obtained for the Fe-5%Cr under 5 MeV proton irradiation are found to be in overall agreement with previous experimental measurements performed under electron irradiation although some differences appear probably due to the different spatial distribution of the created defects and the higher temperature resolution of annealing steps. The RR spectrum obtained reveals the appearance of the structure of stages I and II and also a partial suppression of the stage III peak with respect to previous results obtained after electron irradiation. The stage III suppression is explained as a superposition of vacancy recombination effects and short-range ordering (SRO) effects which are apparently dependent on the spatial distribution of defects created during irradiation. Moreover, recombination phenomena are observed beyond stage III up to 500 K.

Effect of Various Laser Wavelengths on Temperature Changes During Periimplantitis Treatment: An in vitro Study.

PubMed

Monzavi, Abbas; Fekrazad, Reza; Chinipardaz, Zahra; Shahabi, Sima; Behruzi, Roohollah; Chiniforush, Nasim

2018-06-01

This study aimed to investigate and compare temperature change during implant decontamination with different laser types (carbon dioxide [Co2]/diode/neodymium-doped yttrium aluminum garnet [Nd:YAG]/erbium-doped yttrium aluminum garnet [Er:YAG]/antimicrobial photodynamic therapy [aPDT]). Sixty implants were inserted into a bone block cut from a sheep's mandible. A 3 × 8 mm vertical lesion was made at the buccal of each implant. The bone block was placed into a 37°C water bath to simulate the in vivo oral condition. A K-type thermocouple was placed in contact with the implant to register temperature changes at 3 points (apical/middle/coronal). In the entire laser irradiations, the mean of temperature changes remains below 10°C. The apical temperature rise was higher than the coronal and middle regions (P < 0.05), and the apical temperature took longer time to reach the initial temperature (37°C) (P < 0.001). Temperature changes over 10°C occurred at the apical point of the implants with the Co2, Nd:YAG, and diode laser irradiations; however, only the Co2 laser reached the statistical significance in this regard (P < 0.05). Our findings indicate the promising results of Er:YAG laser and aPDT in implant decontamination. Precaution should be taken in the application of Nd:YAG, diode, and especially Co2 lasers.

Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

DOE PAGES

Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.; ...

2016-07-26

Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M 23C 6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

Measuring soil and tree temperatures during prescribed fires with thermocouple probes

Treesearch

Stephen S. Sackett; Sally M. Haase

1992-01-01

Soil and cambium temperatures must be known to ascertain certain effects of prescribed fires on trees. Thermocouple-based systems were devised for measuring soil and cambium temperatures during prescribed fires. The systems, which incorporate both commercially available and custom components, perform three basic functions: data collection, data retrieval, and data...

Measurements of fluctuating gas temperatures using compensated fine wire thermocouples

NASA Astrophysics Data System (ADS)

Nina, M. N. R.; Pita, G. P.

1985-09-01

Thermocouples with three different wire diameters (15, 40 and 50 microns) were used in association with an analog compensation circuit connected to a data acquisition system. Measurements of the time constant were performed using two different heating techniques; Joule effect and external heating by laser beam. The thermocouples were used to quantify the fluctuating temperature field in a hot air jet and in a premixed propane flame. In the reacting case the catalytic effect was evaluated by comparing coated and uncoated wires. Conclusions were also obtained regarding frequency spectra, temperature probability distribution function and time constant.

Technical note: unsafe rectal temperature measurements due to delayed warming of the thermocouple by using a condom. An issue concerning the estimation of the postmortem interval by using Henßge's nomogram.

PubMed

Krap, Tristan; Meurs, Joris; Boertjes, Janine; Duijst, Wilma

2016-03-01

In some cases, in the Netherlands, an additional layer is being added to the thermocouple, used to measure the rectal temperature in medicolegal death investigations. Because of this deviation from the standard method, questions arose regarding the accuracy and precision of the measured temperature. Therefore, a cooling experiment was carried out on a round body made of agar with an average thermal conductivity of 0.454 W/(m °C) while measuring the temperature with and without an additional layer around the thermocouple for three different starting temperatures: 36, 30, and 27 °C. The results show a significant difference between the measured values for the first 5 min when comparing with and without the additional layer. Further, a decrease in precision is present within the first minutes when using an additional layer. Therefore, it is concluded that it is best to measure the rectal temperature without an additional layer around the thermocouple and caution should be taken when measuring with an additional layer.

On the Potential of MAX phases for Nuclear Applications

NASA Astrophysics Data System (ADS)

Tallman, Darin Joseph

Materials within nuclear reactors experience some of the harshest environments currently known to man, including long term operation in extreme temperatures, corrosive media, and fast neutron fluences with up to 100 displacements per atom, dpa. In order to improve the efficiency and safety of current and future reactors, new materials are required to meet these harsh demands. The M n+1AXn phases, a growing family of ternary nano-layered ceramics, possess a desirable combination of metallic and ceramic properties. They are composed of an early transition metal (M), a group 13--16 element (A), and carbon and/or nitrogen (X). The MAX phases are being proposed for use in such extreme environments because of their unique combination of high fracture toughness values and thermal conductivities, machinability, oxidation resistance, and ion irradiation damage tolerance. Previous ion irradiation studies have shown that Ti3SiC2 and Ti3AlC2 resist irradiation damage, maintaining crystallinity up to 50 dpa. The aim of this work was to explore the effect of neutron irradiation, up to 9 dpa and at temperatures of 100 to 1000 °C, on select MAX phases for the first time. The MAX phases Ti3SiC2, Ti 3AlC2, Ti2AlC, and Ti2AlN were synthesized, and irradiated in test reactors that simulate in-pile conditions of nuclear reactors. X-ray diffraction, XRD, pattern refinements of samples revealed a distortion of the crystal lattice after low temperature irradiation, which was not observed after high temperature irradiations. Additionally, the XRD results indicated that Ti3AlC2 and Ti2AlN dissociated after relatively low neutron doses. This led us to focus on Ti 3SiC2 and Ti2AlC. For the first time, dislocation loops were observed in Ti3SiC 2 and Ti2AlC as a result of neutron irradiation. At 1 x 1023 loops/m3, the loop density in Ti2 AlC after irradiation to 0.1 dpa at 700°C was 1.5 orders of magnitude greater than that observed in Ti3SiC2, at 3 x 1021 loops/m3. The Ti2AlC composition appeared more prone to microcracking that Ti3SiC2. Additionally, exceptionally large denuded zones, up to 1 mum in width after 9 dpa irradiations at 500°C, were observed in Ti3SiC2, indicating that point defects readily diffuse to the grain boundaries. Denuded zones of this width, to our knowledge, have never been observed. In comparison, TiC impurity particles were highly damaged with various dislocation loops and defect clusters after irradiation. It is thus apparent that the A-layer, interleaved between MX blocks in the MAX phase nanolayered structure, readily accommodates and/or annihilates point defects, providing significant irradiation damage tolerance. Comparison of defect densities, post-irradiation microstructure, and electrical resistivity showed Ti3SiC2 to have the highest irradiation tolerance. Diffusion bonding of MAX phases to Zircaloy-4 was studied in the 1100 to 1300°C temperature range. The out diffusion of the A-group element into Zircaloy-4 formed Zr-intermetallic compounds that were roughly an order of magnitude thicker in Ti2AlC than Ti3SiC 2. Helium permeability results suggest that the MAX phases behave similarly to other sintered ceramics. Based on the totality of our results, Ti 3SiC2 remains a promising candidate for high temperature nuclear applications, and warrants future exploration. This work provides the foundation for understanding the response of the MAX phases to neutron irradiation, and can now be used to finely tune ion irradiation studies to accurately simulate reactor conditions.

An experimental setup for the simultaneous measurement of thermoelectric power of two samples from 77 K to 500 K.

PubMed

Tripathi, T S; Bala, M; Asokan, K

2014-08-01

We report on an experimental setup for the simultaneous measurement of the thermoelectric power (TEP) of two samples in the temperature range from 77 K to 500 K using optimum electronic instruments. The setup consists of two rectangular copper bars in a bridge arrangement for sample mounting, two surface mount (SM) chip resistors for creating alternate temperature gradient, and a type E thermocouple in differential geometry for gradient temperature (ΔT) measurement across the samples. In addition, a diode arrangement has been made for the alternate heating of SM resistors using only one DC current source. The measurement accuracy of ΔT increases with the differential thermocouple arrangement. For the calibration of the setup, measurements of TEP on a high purity (99.99%) platinum wire and type K thermocouple wires Chromel and Alumel have been performed from 77 K to 500 K with respect to copper lead wires. Additionally, this setup can be utilized to calibrate an unknown sample against a sample of known absolute TEP.

An experimental setup for the simultaneous measurement of thermoelectric power of two samples from 77 K to 500 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, T. S.; Bala, M.; Asokan, K.

2014-08-01

We report on an experimental setup for the simultaneous measurement of the thermoelectric power (TEP) of two samples in the temperature range from 77 K to 500 K using optimum electronic instruments. The setup consists of two rectangular copper bars in a bridge arrangement for sample mounting, two surface mount (SM) chip resistors for creating alternate temperature gradient, and a type E thermocouple in differential geometry for gradient temperature (ΔT) measurement across the samples. In addition, a diode arrangement has been made for the alternate heating of SM resistors using only one DC current source. The measurement accuracy of ΔTmore » increases with the differential thermocouple arrangement. For the calibration of the setup, measurements of TEP on a high purity (99.99%) platinum wire and type K thermocouple wires Chromel and Alumel have been performed from 77 K to 500 K with respect to copper lead wires. Additionally, this setup can be utilized to calibrate an unknown sample against a sample of known absolute TEP.« less

Comparison of IR thermography and thermocouple measurement of heat loss from rabbit pinna.

PubMed

Mohler, F S; Heath, J E

1988-02-01

The temperature of the pinnae of male New Zealand White rabbits was measured by use of infrared thermography. At ambient temperatures of 15, 20, and 25 degrees C, the average pinna temperatures were 23.0, 28.7, and 36.2 degrees C, respectively. From these temperatures, average heat loss from the total pinna surface area was calculated to be 2.8, 3.3, and 4.4 W, respectively. Preoptic temperature changes also affect the vasomotor state of the rabbit. At an ambient temperature of 20 degrees C, cooling the preoptic area of the rabbit by approximately 1 degree C resulted in an average pinna temperature of 26.5 degrees C and a heat loss of 2.4 W. Heating the preoptic area by approximately 1 degree C resulted in an average pinna temperature of 33.5 degrees C and a heat loss of 5.4 W. Finally, pinna temperatures were measured by use of a thermocouple and infrared thermography simultaneously. When the pinnae were vasodilated, the thermocouple measurements were consistently higher than the pinna surface temperatures measured thermographically. When the pinnae were vasoconstricted, the thermocouple measurements were consistently lower than the pinna surface temperatures measured thermographically. The discrepancy between the two methods of measurement is discussed.

Performance and Durability of Thin Film Thermocouple Array on a Porous Electrode.

PubMed

Guk, Erdogan; Ranaweera, Manoj; Venkatesan, Vijay; Kim, Jung-Sik

2016-08-23

Management of solid oxide fuel cell (SOFC) thermal gradients is vital to limit thermal expansion mismatch and thermal stress. However, owing to harsh operation conditions of SOFCs and limited available space in stack configuration, the number of techniques available to obtain temperature distribution from the cell surface is limited. The authors previously developed and studied a thermocouple array pattern to detect surface temperature distribution on an SOFC in open circuit conditions. In this study, the performance in terms of mechanical durability and oxidation state of the thin film thermoelements of the thermocouple array on the porous SOFC cathode is investigated. A thin-film multi-junction thermocouple array was sputter deposited using a magnetron sputter coater. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) characterisation techniques were carried out to understand characteristics of the thin film before and after temperature (20 °C-800 °C) measurement. Temperature readings from the sensor agreed well with the closely placed commercial thermocouple during heating segments. However, a sensor failure occurred at around 350 °C during the cooling segment. The SEM and XPS tests revealed cracks on the thin film thermoelements and oxidation to the film thickness direction.

Performance and Durability of Thin Film Thermocouple Array on a Porous Electrode

PubMed Central

Guk, Erdogan; Ranaweera, Manoj; Venkatesan, Vijay; Kim, Jung-Sik

2016-01-01

Management of solid oxide fuel cell (SOFC) thermal gradients is vital to limit thermal expansion mismatch and thermal stress. However, owing to harsh operation conditions of SOFCs and limited available space in stack configuration, the number of techniques available to obtain temperature distribution from the cell surface is limited. The authors previously developed and studied a thermocouple array pattern to detect surface temperature distribution on an SOFC in open circuit conditions. In this study, the performance in terms of mechanical durability and oxidation state of the thin film thermoelements of the thermocouple array on the porous SOFC cathode is investigated. A thin-film multi-junction thermocouple array was sputter deposited using a magnetron sputter coater. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) characterisation techniques were carried out to understand characteristics of the thin film before and after temperature (20 °C–800 °C) measurement. Temperature readings from the sensor agreed well with the closely placed commercial thermocouple during heating segments. However, a sensor failure occurred at around 350 °C during the cooling segment. The SEM and XPS tests revealed cracks on the thin film thermoelements and oxidation to the film thickness direction. PMID:27563893

Validity and reliability of temperature measurement by heat flow thermistors, flexible thermocouple probes and thermistors in a stirred water bath.

PubMed

Versey, Nathan G; Gore, Christopher J; Halson, Shona L; Plowman, Jamie S; Dawson, Brian T

2011-09-01

We determined the validity and reliability of heat flow thermistors, flexible thermocouple probes and general purpose thermistors compared with a calibrated reference thermometer in a stirred water bath. Validity (bias) was defined as the difference between the observed and criterion values, and reliability as the repeatability (standard deviation or typical error) of measurement. Data were logged every 5 s for 10 min at water temperatures of 14, 26 and 38 °C for ten heat flow thermistors and 24 general purpose thermistors, and at 35, 38 and 41 °C for eight flexible thermocouple probes. Statistical analyses were conducted using spreadsheets for validity and reliability, where an acceptable bias was set at ±0.1 °C. None of the heat flow thermistors, 17% of the flexible thermocouple probes and 71% of the general purpose thermistors met the validity criterion for temperature. The inter-probe reliabilities were 0.03 °C for heat flow thermistors, 0.04 °C for flexible thermocouple probes and 0.09 °C for general purpose thermistors. The within trial intra-probe reliability of all three temperature probes was 0.01 °C. The results suggest that these temperature sensors should be calibrated individually before use at relevant temperatures and the raw data corrected using individual linear regression equations.

Instrumentation System Diagnoses a Thermocouple

NASA Technical Reports Server (NTRS)

Perotti, Jose; Santiago, Josephine; Mata, Carlos; Vokrot, Peter; Zavala, Carlos; Burns, Bradley

2008-01-01

An improved self-validating thermocouple (SVT) instrumentation system not only acquires readings from a thermocouple but is also capable of detecting deterioration and a variety of discrete faults in the thermocouple and its lead wires. Prime examples of detectable discrete faults and deterioration include open- and short-circuit conditions and debonding of the thermocouple junction from the object, the temperature of which one seeks to measure. Debonding is the most common cause of errors in thermocouple measurements, but most prior SVT instrumentation systems have not been capable of detecting debonding. The improved SVT instrumentation system includes power circuitry, a cold-junction compensator, signal-conditioning circuitry, pulse-width-modulation (PWM) thermocouple-excitation circuitry, an analog-to-digital converter (ADC), a digital data processor, and a universal serial bus (USB) interface. The system can operate in any of the following three modes: temperature measurement, thermocouple validation, and bonding/debonding detection. The software running in the processor includes components that implement statistical algorithms to evaluate the state of the thermocouple and the instrumentation system. When the power is first turned on, the user can elect to start a diagnosis/ monitoring sequence, in which the PWM is used to estimate the characteristic times corresponding to the correct configuration. The user also has the option of using previous diagnostic values, which are stored in an electrically erasable, programmable read-only memory so that they are available every time the power is turned on.

Spatial and Temporal Variabilities of Solar and Longwave Radiation Fluxes below a Coniferous Forest in the French Alps

NASA Astrophysics Data System (ADS)

Sicart, J. E.; Ramseyer, V.; Lejeune, Y.; Essery, R.; Webster, C.; Rutter, N.

2017-12-01

At high altitudes and latitudes, snow has a large influence on hydrological processes. Large fractions of these regions are covered by forests, which have a strong influence on snow accumulation and melting processes. Trees absorb a large part of the incoming shortwave radiation and this heat load is mostly dissipated as longwave radiation. Trees shelter the snow surface from wind, so sub-canopy snowmelt depends mainly on the radiative fluxes: vegetation attenuates the transmission of shortwave radiation but enhances longwave irradiance to the surface. An array of 13 pyranometers and 11 pyrgeometers was deployed on the snow surface below a coniferous forest at the CEN-MeteoFrance Col de Porte station in the French Alps (1325 m asl) during the 2017 winter in order to investigate spatial and temporal variabilities of solar and infrared irradiances in different meteorological conditions. Sky view factors measured with hemispherical photographs at each radiometer location were in a narrow range from 0.2 to 0.3. The temperature of the vegetation was measured with IR thermocouples and an IR camera. In clear sky conditions, the attenuation of solar radiation by the canopy reached 96% and its spatial variability exceeded 100 W m-2. Longwave irradiance varied by 30 W m-2 from dense canopy to gap areas. In overcast conditions, the spatial variabilities of solar and infrared irradiances were reduced and remained closely related to the sky view factor. A simple radiative model taking into account the penetration through the canopy of the direct and diffuse solar radiation, and isotropic infrared emission of the vegetation as a blackbody emitter, accurately reproduced the dynamics of the radiation fluxes at the snow surface. Model results show that solar transmissivity of the canopy in overcast conditions is an excellent proxy of the sky view factor and the emitting temperature of the vegetation remained close to the air temperature in this typically dense Alpine forest.

Thin film thermocouples for high temperature turbine application

NASA Technical Reports Server (NTRS)

Martin, Lisa C.

1991-01-01

The objective is to develop thin film thermocouples (TFTC) for Space Shuttle Main Engine (SSME) components such as the high pressure fuel turbopump (HPFTP) blades and to test TFTC survivability and durability in the SSME environment. The purpose for developing TFTC's for SSME components is to obtain blade temperatures for computational models developed for fluid mechanics and structures. The TFTC must be able to withstand the presence of high temperature, high pressure hydrogen as well as a severe thermal transient due to a cryogenic to combustion temperature change. The TFTC's will eventually be installed and tested on SSME propulsion system components in the SSME test bed engine. The TFTC's were successfully fabricated on flat coupons of MAR-M 246 (Hf+), which is the superalloy material used for HPFTP turbine blades. The TFTC's fabricated on flat coupons survived thermal shock cycling as well as testing in a heat flux measurement facility which provided a rapid thermal transient. The same fabrication procedure was used to deposit TFTC's on HPFTP first stage rotor blades. Other results from the experiments are presented, and future testing plans are discussed.

An Integrated-Circuit Temperature Sensor for Calorimetry and Differential Temperature Measurement

NASA Astrophysics Data System (ADS)

Muyskens, Mark

1997-07-01

Our application of an integrated-circuit (IC) temperature sensor which is easy-to-use, inexpensive, rugged, easily computer-interfacable and has good precision is described. The design, based on the National Semiconductor LM35 IC chip, avoids some of the difficulties associated with conventional sensors (thermocouples, thermistors, and platinum resistance thermometers) and a previously described IC sensor. The sensor can be used with a variety of data-acquisition systems. Applications range from general chemistry to physical chemistry, particularly where computer interfaced, digital temperature measurement is desired. Included is a detailed description of our current design with suggestions for improvement and a performance evaluation of the precision in differential measurement and the time constant for responding to temperature change.

Optimal irradiance for sintering of inkjet-printed Ag electrodes with a 532nm CW laser

NASA Astrophysics Data System (ADS)

Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Hwang, Jun Young; Moon, Seung Jae

2013-09-01

Industrial solar cell fabrication generally adopts printing process to deposit the front electrodes, which needs additional heat treatment after printing to enhance electrical conductivity. As a heating method, laser irradiation draws attention not only because of its special selectivity, but also because of its intense heating to achieve high electric conductivity which is essential to reduce ohmic loss of solar cells. In this study, variation of electric conductivity was examined with laser irradiation having various beam intensity. 532 nm continuous wave (CW) laser was irradiated on inkjet-printed silver lines on glass substrate and electrical resistance was measured in situ during the irradiation. The results demonstrate that electric conductivity varies nonlinearly with laser intensity, having minimum specific resistance of 4.1 x 10-8 Ωm at 529 W/cm2 irradiation. The results is interesting because the specific resistance achieved by the present laser irradiation was about 1.8 times lower than the best value obtainable by oven heating, even though it was still higher by 2.5 times than that of bulk silver. It is also demonstrated that the irradiation time, needed to finish sintering process, decreases with laser intensity. The numerical simulation of laser heating showed that the optimal heating temperature could be as high as 300 oC for laser sintering, while it was limited to 250 oC for oven sintering. The nonlinear response of sintering with heating intensity was discussed, based on the results of FESEM images and XRD analysis.

Effects produced by iodine irradiation on high resistivity silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazanu, S.; Slav, A.; Lepadatu, A.-M.

2012-12-10

The effects of 5 Multiplication-Sign 10{sup 11} cm{sup -26+}I{sup 127} ions of 28 MeV kinetic energy on high resistivity (100) Si were studied. The profile of primary defects was simulated. The defects produced by irradiation which act as traps were investigated. Thermally stimulated current measurements without externally applied bias were used, and for this the traps were charged by illuminating samples with 1000, 800, and 400 nm wavelengths. The discharge currents were recorded and modeled, and therefore the parameters of the traps were determined. The presence of I ions, heavier than Si, stopped into the target was modeled as amore » temperature independent electric field.« less

A thermocouple thermode for small animals

NASA Technical Reports Server (NTRS)

Williams, B. A.

1972-01-01

Thermode composed of two thin-walled stainless steel hypodermic needles and cooper-constantan thermocouple or small thermistor to indicate temperature at point of perfusion is used to measure brain temperature in animals. Because of relatively small size of thermode, structural damage to brain is minimized.

Influence of heat treatment on structural, mechanical and wear properties of crosslinked UHMWPE.

PubMed

Chiesa, R; Moscatelli, M; Giordano, C; Siccardi, F; Cigada, A

2004-01-01

New crosslinked ultra high molecular weight polyethylenes (UHMWPEs) have recently been developed, characterized and introduced in clinical applications. UHMWPE cross-linking treatments are very promising for reducing osteolysis induced by wear debris. The irradiation type, gamma or beta, the dosage and the thermal treatment performed during or following the irradiation process are all factors affecting polyethylene wear resistance. Thermal stabilization treatments performed after or during the irradiation process at a temperature above melting point (i.e. >130 degrees C) have been proven to effectively remove the free radicals generated during irradiation from UHMWPE, but their effect on the mechanical properties of UHMWPE are not completely clear. In addition to wear rate reduction, maintaining good mechanical properties is fundamental aspect in designing the new generation of crosslinked UHMWPE for artificial load bearing materials, especially considering the application in total knee replacements. In this study, we investigated the influence of different stabilization treatments, performed after gamma irradiation, on structural, wear and mechanical properties of UHMWPE. We performed four different stabilization treatments, with different temperatures and cooling rates, on 100 kGy gamma irradiated UHMWPE. Structural properties of UHMWPE were assessed by differential scanning calorimetry (DSC). To assess the mechanical performance of the materials, uni-axial tensile tests were performed according to the ASTM D638 standard, bi-axial tension performance was evaluated by small punch tests (ASTM F2183-02), toughness resistance was evaluated by the Izod method (ASTM F648), and cold flow resistance was analysed by a dynamic compressive test. Evaluation of wear resistance was by a multidirectional pin-on-disk screening machine. Materials considered were in "aged" and "non-aged" conditions. Results confirmed that cross-linking greatly enhances UHMWPE wear resistance, but introduces some detrimental effects on the mechanical properties. In this study, we found that the negative ef-fects on the mechanical properties of crosslinked UHMWPE can be modulated, to some extent, by choosing a thermal stabiliza-tion treatment at a correct temperature and cooling rate. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 20-8).

Measurement of thermoelectric inhomogeneity of thermocouples

NASA Technical Reports Server (NTRS)

Reed, R. P.; Bauserman, Willard A., Jr.

1993-01-01

In a thermocouple probe that has significantly inhomogeneous legs, the relationship between emf and temperature is indefinite and depends on temperature distribution along the circuit. An inhomogeneous thermocouple cannot be calibrated to arbitrarily small uncertainty. Therefore, testing for inhomogeneities is a necessary preliminary to meaningful calibration. As most significant inhomogeneity that does occur is introduced during use (and sometimes during calibration) a post-test inhomogeneity measurement should also be employed to detect degradation that might have substantially affected the data. This paper presents a practical test method that is being developed for the observation, interpretation, and application of thermoelectric inhomogeneity as a routine quality assurance measurement that is an essential complement to traditional sheathed thermocouple calibration.

Operational methods of thermodynamics. Volume 1 - Temperature measurement

NASA Astrophysics Data System (ADS)

Eder, F. X.

The principles of thermometry are examined, taking into account the concept of temperature, the Kelvin scale, the statistical theory of heat, negative absolute temperatures, the thermodynamic temperature scale, the thermodynamic temperature scale below 1 K, noise thermometry, temperature scales based on black-body radiation, acoustical thermometry, and the International Practical Temperature Scale 1968. Aspects of practical temperature measurement are discussed, giving attention to thermometers based on the expansion of a gas or a liquid, instruments utilizing the relative thermal expansion of two different metals, devices measuring the vapor pressure of a liquid, thermocouples, resistance thermometers, radiation pyrometers of various types, instruments utilizing the temperature dependence of a number of material characteristics, devices for temperature control, thermometer calibration, and aspects of thermometer installation and inertia. A description is presented of the approaches employed for the measurement of low temperatures.

The Combined Use of a Gas-Controlled Heat Pipe and a Copper Point to Improve the Calibration of Thermocouples up to 1100 ˚C

NASA Astrophysics Data System (ADS)

Astrua, M.; Iacomini, L.; Battuello, M.

2008-10-01

The calibration of platinum-based thermocouples from 420 °C to 1,100 ˚C is currently carried out at INRIM making use of two different apparatus: for temperatures below 930 ˚C, a potassium gas-controlled heat pipe (GCHP) is used, whereas a metal-block furnace is adopted for higher temperatures. The standard uncertainty of the reference temperature obtained in the lower temperature range is almost one order of magnitude better than in the higher temperature range. A sealed copper cell was investigated to see if it could be used to calibrate thermocouples above 930 ˚C with a lower uncertainty than our current procedures allowed. The cell was characterized with Type S and Pt/Pd thermocouples and with an HTPRT. The freezing plateaux were flat within 0.01 ˚C and lasted up to 1 h with a repeatability of 0.02 ˚C. The temperature of the cell was determined with a standard uncertainty of 0.04 ˚C. Hence, the copper cell was found to be superior to the comparator furnace for the calibration of platinum-based thermocouples because of the significant decrease in the uncertainty that it provides. An analysis was also carried out on the calibration of Pt/Pd thermocouples, and it was found that the combined use of the potassium GCHP and the Cu fixed-point cell is adequate to exploit the potential of these sensors in the range from 420 °C to 1,084 °C. A comparison with a fixed-point calibration was also made which gave rise to agreement within 0.07 ˚C between the two approaches.

In-situ transport and microstructural evolution in GaN Schottky diodes and epilayers exposed to swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Kumar, Ashish; Singh, R.; Kumar, Parmod; Singh, Udai B.; Asokan, K.; Karaseov, Platon A.; Titov, Andrei I.; Kanjilal, D.

2018-04-01

A systematic investigation of radiation hardness of Schottky barrier diodes and GaN epitaxial layers is carried out by employing in-situ electrical resistivity and cross sectional transmission electron microscopy (XTEM) microstructure measurements. The change in the current transport mechanism of Au/n-GaN Schottky barrier diodes due to irradiation is reported. The role of irradiation temperature and ion type was also investigated. Creation of damage is studied in low and medium electron energy loss regimes by selecting different ions, Ag (200 MeV) and O (100 MeV) at various fluences at two irradiation temperatures (80 K and 300 K). GaN resistivity increases up to 6 orders of magnitude under heavy Ag ions. Light O ion irradiation has a much lower influence on sheet resistance. The presence of isolated defect clusters in irradiated GaN epilayers is evident in XTEM investigation which is explained on the basis of the thermal spike model.

Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakos, James Thomas

2004-04-01

It would not be possible to confidently qualify weapon systems performance or validate computer codes without knowing the uncertainty of the experimental data used. This report provides uncertainty estimates associated with thermocouple data for temperature measurements from two of Sandia's large-scale thermal facilities. These two facilities (the Radiant Heat Facility (RHF) and the Lurance Canyon Burn Site (LCBS)) routinely gather data from normal and abnormal thermal environment experiments. They are managed by Fire Science & Technology Department 09132. Uncertainty analyses were performed for several thermocouple (TC) data acquisition systems (DASs) used at the RHF and LCBS. These analyses apply tomore » Type K, chromel-alumel thermocouples of various types: fiberglass sheathed TC wire, mineral-insulated, metal-sheathed (MIMS) TC assemblies, and are easily extended to other TC materials (e.g., copper-constantan). Several DASs were analyzed: (1) A Hewlett-Packard (HP) 3852A system, and (2) several National Instrument (NI) systems. The uncertainty analyses were performed on the entire system from the TC to the DAS output file. Uncertainty sources include TC mounting errors, ANSI standard calibration uncertainty for Type K TC wire, potential errors due to temperature gradients inside connectors, extension wire uncertainty, DAS hardware uncertainties including noise, common mode rejection ratio, digital voltmeter accuracy, mV to temperature conversion, analog to digital conversion, and other possible sources. Typical results for 'normal' environments (e.g., maximum of 300-400 K) showed the total uncertainty to be about {+-}1% of the reading in absolute temperature. In high temperature or high heat flux ('abnormal') thermal environments, total uncertainties range up to {+-}2-3% of the reading (maximum of 1300 K). The higher uncertainties in abnormal thermal environments are caused by increased errors due to the effects of imperfect TC attachment to the test item. 'Best practices' are provided in Section 9 to help the user to obtain the best measurements possible.« less

Quantitative ultrasound imaging for monitoring in situ high-intensity focused ultrasound exposure.

PubMed

Ghoshal, Goutam; Kemmerer, Jeremy P; Karunakaran, Chandra; Abuhabsah, Rami; Miller, Rita J; Sarwate, Sandhya; Oelze, Michael L

2014-10-01

Quantitative ultrasound (QUS) imaging is hypothesized to map temperature elevations induced in tissue with high spatial and temporal resolution. To test this hypothesis, QUS techniques were examined to monitor high-intensity focused ultrasound (HIFU) exposure of tissue. In situ experiments were conducted on mammary adenocarcinoma tumors grown in rats and lesions were formed using a HIFU system. A thermocouple was inserted into the tumor to provide estimates of temperature at one location. Backscattered time-domain waveforms from the tissue during exposure were recorded using a clinical ultrasonic imaging system. Backscatter coefficients were estimated using a reference phantom technique. Two parameters were estimated from the backscatter coefficient (effective scatterer diameter (ESD) and effective acoustic concentration (EAC). The changes in the average parameters in the regions corresponding to the HIFU focus over time were correlated to the temperature readings from the thermocouple. The changes in the EAC parameter were consistently correlated to temperature during both heating and cooling of the tumors. The changes in the ESD did not have a consistent trend with temperature. The mean ESD and EAC before exposure were 120 ± 16 μm and 32 ± 3 dB/cm3, respectively, and changed to 144 ± 9 μm and 51 ± 7 dB/cm3, respectively, just before the last HIFU pulse was delivered to the tissue. After the tissue cooled down to 37 °C, the mean ESD and EAC were 126 ± 8 μm and 35 ± 4 dB/cm3, respectively. Peak temperature in the range of 50-60 °C was recorded by a thermocouple placed just behind the tumor. These results suggest that QUS techniques have the potential to be used for non-invasive monitoring of HIFU exposure. © The Author(s) 2014.

Evidence of a temperature transition for denuded zone formation in nanocrystalline Fe under He irradiation

DOE PAGES

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.; ...

2016-10-18

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

The study on the electrical resistivity of Cu/V multilayer films subjected to helium (He) ion irradiation

NASA Astrophysics Data System (ADS)

Wang, P. P.; Xu, C.; Fu, E. G.; Du, J. L.; Gao, Y.; Wang, X. J.; Qiu, Y. H.

2018-05-01

Sputtering-deposited Cu/V multilayer films with the individual layer thickness varying from 2.5 nm to 100 nm were irradiated by 1 MeV helium (He) ion at the fluence of 6 ×1016 ions ·cm-2 at room temperature. The resistivity of Cu/V multilayer films after ion irradiation was evaluated as a function of individual layer thickness at 300 K and compared with their resistivity before ion irradiation. The results show that the resistivity change before and after ion irradiation is largely determined by the interface structure, grain boundary and radiation induced defects. A model amended based on the model used in describing the resistivity of as-deposited Cu/V multilayer films was proposed to describe the resistivity of ion irradiated Cu/V multilayer films by considering the point defects induced by ion irradiation, the effect of interface absorption on defects and the effect of interface microstructure in the multilayer films.

Application of remote sensing in estimating evapotranspiration in the Platte river basin

NASA Technical Reports Server (NTRS)

Blad, B. L.; Rosenberg, N. J.

1976-01-01

A 'resistance model' and a mass transport model for estimating evapotranspiration (ET) were tested on large fields of naturally subirrigated alfalfa. Both models make use of crop canopy temperature data. Temperature data were obtained with an IR thermometer and with leaf thermocouples. A Bowen ratio-energy balance (BREB) model, adjusted to account for underestimation of ET during periods of strong sensible heat advection, was used as the standard against which the resistance and mass transport models were compared. Daily estimates by the resistance model were within 10% of estimates made by the BREB model. Daily estimates by the mass transport model did not agree quite as well. Performance was good on clear and cloudy days and also during periods of non-advection and strong advection of sensible heat. The performance of the mass transport and resistance models was less satisfactory for estimation of fluxes of latent heat for short term periods. Both models tended to overestimate at low LE fluxes.

Temporary Thermocouple Attachment for Thermal/Vacuum Testing at Non-Extreme Temperatures

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.; Wright, Sarah E.

2016-01-01

Post-test examination and data analysis that followed a two week long vacuum test showed that numerous self-stick thermocouples became detached from the test article. The thermocouples were reattached with thermally conductive epoxy and the test was repeated to obtain the required data. Because the thermocouple detachment resulted in significant expense and rework, it was decided to investigate the temporary attachment methods used around NASA and to perform a test to assess their efficacy. The present work describes the original test and the analysis that showed that the thermocouples had become detached, temporary thermocouple attachment methods assessed in the retest and in the thermocouple attachment test, and makes a recommendation for attachment methods for future tests.

Improving oxidation resistance and thermal insulation of thermal barrier coatings by intense pulsed electron beam irradiation

NASA Astrophysics Data System (ADS)

Mei, Xianxiu; Liu, Xiaofei; Wang, Cunxia; Wang, Younian; Dong, Chuang

2012-12-01

In this paper, intense pulsed electron beam was used for the irradiation treatment of 6-8% Y2O3-stablized ZrO2 thermal barrier coating prepared by electron beam-physical vapor deposition to achieve the "sealing" of columnar crystals, thus improving their thermal insulation properties and high temperature oxidation resistance. The electron beam parameters used were: pulse duration 200 μs, electron voltage 15 kV, energy density 3, 5, 8, 15, 20 J/cm2, and pulsed numbers 30. 1050 °C cyclic oxidation and static oxidation experiments were used for the research on oxidation resistance of the coatings. When the energy density of the electron beam was larger than 8 J/cm2, ZrO2 ceramic coating surface was fully re-melted and became smooth, dense and shiny. The coating changed into a smooth polycrystalline structure, thus achieving the "sealing" effect of the columnar crystals. After irradiations with the energy density of 8-15 J/cm2, the thermally grown oxide coating thickness decreased significantly in comparison with non-irradiated coatings, showing that the re-melted coating improved the oxidation resistance of the coatings. The results of thermal diffusivity test by laser flash method showed that the thermal diffusion rate of the irradiated coating was lower than that of the coating without irradiation treatment, and the thermal insulation performance of irradiated coating was improved.

Target depth dependence of damage rate in metals by 150 MeV proton irradiation

NASA Astrophysics Data System (ADS)

Yoshiie, T.; Ishi, Y.; Kuriyama, Y.; Mori, Y.; Sato, K.; Uesugi, T.; Xu, Q.

2015-01-01

A series of irradiation experiments with 150 MeV protons was performed. The relationship between target depth (or shield thickness) and displacement damage during proton irradiation was obtained by in situ electrical resistance measurements at 20 K. Positron annihilation lifetime measurements were also performed at room temperature after irradiation, as a function of the target thickness. The displacement damage was found to be high close to the beam incident surface area, and decreased with increasing target depth. The experimental results were compared with damage production calculated with an advanced Monte Carlo particle transport code system (PHITS).

40 CFR 63.3350 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2012 CFR

2012-07-01

..., whichever is greater. The thermocouple or temperature sensor must be installed in the combustion chamber at... or ±1 degree Celsius, whichever is greater. The thermocouple or temperature sensor must be installed...

40 CFR 63.3350 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2013 CFR

2013-07-01

..., whichever is greater. The thermocouple or temperature sensor must be installed in the combustion chamber at... or ±1 degree Celsius, whichever is greater. The thermocouple or temperature sensor must be installed...

40 CFR 63.3350 - If I use a control device to comply with the emission standards, what monitoring must I do?

Code of Federal Regulations, 2014 CFR

2014-07-01

..., whichever is greater. The thermocouple or temperature sensor must be installed in the combustion chamber at... or ±1 degree Celsius, whichever is greater. The thermocouple or temperature sensor must be installed...

Experimental investigations of an AC pulse heating method for vehicular high power lithium-ion batteries at subzero temperatures

NASA Astrophysics Data System (ADS)

Zhu, Jiangong; Sun, Zechang; Wei, Xuezhe; Dai, Haifeng; Gu, Weijun

2017-11-01

Effect of the AC (alternating current) pulse heating method on battery SoH (state of health) for large laminated power lithium-ion batteries at low temperature is investigated experimentally. Firstly, excitation current frequencies, amplitudes, and voltage limitations on cell temperature evolution are studied. High current amplitudes facilitate the heat accumulation and temperature rise. Low frequency region serves as a good innovation to heat the battery because of the large impedance. Wide voltage limitations also enjoy better temperature evolution owing to the less current modulation, but the temperature difference originated from various voltage limitations attenuates due to the decrement of impedance resulting from the temperature rise. Experiments with the thermocouple-embedded cell manifest good temperature homogeneity between the battery surface and interior during the AC heating process. Secondly, the cell capacity, Direct Current resistance and Electrochemical Impedance Spectroscopy are all calibrated to assess the battery SoH after the hundreds of AC pulse heating cycles. Also, all cells are disassembled to investigate the battery internal morphology with the employment of Scanning Electron Microscope and Energy-Dispersive x-ray Spectroscopy techniques. The results indicate that the AC heating method does not aggravate the cell degradation even in the low frequency range (0.5 Hz) under the normal voltage protection limitation.

Tile Surface Thermocouple Measurement Challenges from the Orbiter Boundary Layer Transition Flight Experiment

NASA Technical Reports Server (NTRS)

Campbell, Charles H.; Berger, Karen; Anderson, Brian

2012-01-01

Hypersonic entry flight testing motivated by efforts seeking to characterize boundary layer transition on the Space Shuttle Orbiters have identified challenges in our ability to acquire high quality quantitative surface temperature measurements versus time. Five missions near the end of the Space Shuttle Program implemented a tile surface protuberance as a boundary layer trip together with tile surface thermocouples to capture temperature measurements during entry. Similar engineering implementations of these measurements on Discovery and Endeavor demonstrated unexpected measurement voltage response during the high heating portion of the entry trajectory. An assessment has been performed to characterize possible causes of the issues experienced during STS-119, STS-128, STS-131, STS-133 and STS-134 as well as similar issues encountered during other orbiter entries.

High rate discharge studies of Li/SO2 cells

NASA Astrophysics Data System (ADS)

Dallek, S.; Bis, R. F.; Bowers, F. M.

Experimental D-size spirally-wound 3V 10 A-hr cells were used in the reported study. The cells were instrumented with four iron-constantan thermocouples. It was found that during a discharge of a thermally insulated cell, the greatest amount of heat builds up in the center of the cell. The heat build-up appears to be purely resistive in nature. Concerning the safe use of these cells, it has been demonstrated that at very high rates of discharge, e.g., 10 A, cells may vent violently and cause a fire. At this high rate of discharge, the internal cell temperature exceeded the melting point of the lithium anode which is in the form of an unsupported strip. Thus, contact of the highly reactive molten lithium with other reactive species in the cell is possible under these conditions and could result in a very exothermic chemical reaction.

Argonne Bubble Experiment Thermal Model Development III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buechler, Cynthia Eileen

This report describes the continuation of the work reported in “Argonne Bubble Experiment Thermal Model Development” and “Argonne Bubble Experiment Thermal Model Development II”. The experiment was performed at Argonne National Laboratory (ANL) in 2014. A rastered 35 MeV electron beam deposited power in a solution of uranyl sulfate, generating heat and radiolytic gas bubbles. Irradiations were performed at beam power levels between 6 and 15 kW. Solution temperatures were measured by thermocouples, and gas bubble behavior was recorded. The previous report2 described the Monte-Carlo N-Particle (MCNP) calculations and Computational Fluid Dynamics (CFD) analysis performed on the as-built solution vesselmore » geometry. The CFD simulations in the current analysis were performed using Ansys Fluent, Ver. 17.2. The same power profiles determined from MCNP calculations in earlier work were used for the 12 and 15 kW simulations. The primary goal of the current work is to calculate the temperature profiles for the 12 and 15 kW cases using reasonable estimates for the gas generation rate, based on images of the bubbles recorded during the irradiations. Temperature profiles resulting from the CFD calculations are compared to experimental measurements.« less

Dynamic gas temperature measurement system. Volume 2: Operation and program manual

NASA Technical Reports Server (NTRS)

Purpura, P. T.

1983-01-01

The hot section technology (HOST) dynamic gas temperature measurement system computer program acquires data from two type B thermocouples of different diameters. The analysis method determines the in situ value of an aerodynamic parameter T, containing the heat transfer coefficient from the transfer function of the two thermocouples. This aerodynamic parameter is used to compute a fequency response spectrum and compensate the dynamic portion of the signal of the smaller thermocouple. The calculations for the aerodynamic parameter and the data compensation technique are discussed. Compensated data are presented in either the time or frequency domain, time domain data as dynamic temperature vs time, or frequency domain data.

The use of distributed temperature sensing technology for monitoring wildland fire intensity and distribution.

NASA Astrophysics Data System (ADS)

Ochoa, C. G.; Cram, D.; Hatch, C. E.; Tyler, S. W.

2014-12-01

Distributed temperature sensing (DTS) technology offers a viable alternative for accurately measuring wildland fire intensity and distribution in real time applications. We conducted an experiment to test the use of DTS as an alternative technology to monitor prescribed fire temperatures in real time and across a broad spatial scale. The custom fiber-optic cable consisted of three fiber optic lines buffered by polyamide, copper, and polyvinyl chloride, respectively, each armored in a stainless steel tube backfilled with Nitrogen gas. The 150 m long cable was deployed in three different 20 by 26 m experimental plots of short-grass rangeland in central New Mexico. Cable was arranged to maximize coverage of the experimental plots and allow cross-comparison between two main parallel straight-line sections approximately 8 m apart. A DTS system recorded fire temperatures every three seconds and integrated every one meter. A series of five thermocouples attached to a datalogger were placed at selected locations along the cable and also recorded temperature data every three seconds on each fiber. Results indicate that in general there is good agreement between thermocouple-measured and DTS-measured temperatures. A close match in temperature between DTS and thermocouples was particularly observed during the rising limb but not so much during the decline. The metal armoring of the fiber-optic cable remained hot longer than the thermocouples after the flames had passed. The relatively short-duration, high-intensity, prescribed burn fire in each plot resulted in temperatures reaching up to 450 degrees Celsius. In addition, DTS data allow for illustration of the irregular nature of flame speed and travel path across the rangeland grasses, a phenomenon that was impossible to quantify without the use of this tool. This study adds to the understanding of using DTS as a new alternative tool for better characterizing wildland fire intensity, distribution and travel patterns, and establishes the baseline for expanding these test plot results to larger spatial scales.

Determination of combustion gas temperatures by infrared radiometry in sooting and nonsooting flames

NASA Technical Reports Server (NTRS)

Lyons, Valerie J.; Gracia-Salcedo, Carmen M.

1989-01-01

Flame temperatures in nonsooting and sooting environments were successfully measured by radiometry for pre-mixed propane-oxygen laminar flames stabilized on a water-cooled, porous sintered-bronze burner. The measured temperatures in the nonsooting flames were compared with fine-wire thermocouple measurements. The results show excellent agreement below 1700 K, and when the thermocouple measurements were corrected for radiation effects, the agreement was good for even higher temperatures. The benefits of radiometry are: (1) the flow is not disturbed by an intruding probe, (2) calibration is easily done using a blackbody source, and (3) measurements can be made even with soot present. The theory involved in the radiometry measurements and the energy balance calculations used to correct the thermocouple temperature measurements are discussed.

Optimal parameters for arterial repair using light-activated surgical adhesives.

PubMed

Soller, Eric C; Hoffman, Grant T; McNally-Heintzelman, Karen M

2003-01-01

The clinical acceptance of laser-tissue repair techniques is dependent on the reproducibility of viable repairs. Reproducibility is dependent on two factors: (i) the choice of materials to be used as the adhesive; and (ii) obtaining temperatures high enough to cause protein denaturation at the vital tissue interface without causing excessive thermal damage to the surrounding tissue. The use of a polymer scaffold as a carrier for the protein solder provides for uniform application of the solder to the tissue, thus allowing for pre-selection of optimal laser parameters. The scaffold also facilitates precise tissue alignment and ease of clinical application. In addition, the scaffold can be doped with various pharmaceuticals such as hemostatic and thrombogenic agents to aid wound healing. An ex vivo study was performed to correlate solder and tissue temperature with the tensile strength of arterial repairs formed using scaffold-enhanced light-activated surgical adhesives. Previous studies by our group using solid protein solder without the scaffold indicate that a solder/tissue, interface temperature of 65 degrees C is optimal. Using this parameter as a benchmark, laser irradiance was varied and temperatures were recorded at the surface and at the tissue interface of scaffold-enhanced protein solder using an infrared temperature monitoring system, designed by the researchers, and a type-K thermocouple, respectively.

Recent advances and issues in development of silicon carbide composites for fusion applications

NASA Astrophysics Data System (ADS)

Nozawa, T.; Hinoki, T.; Hasegawa, A.; Kohyama, A.; Katoh, Y.; Snead, L. L.; Henager, C. H., Jr.; Hegeman, J. B. J.

2009-04-01

Radiation-resistant advanced silicon carbide (SiC/SiC) composites have been developed as a promising candidate of the high-temperature operating advanced fusion reactor. With the completion of the 'proof-of-principle' phase in development of 'nuclear-grade' SiC/SiC composites, the R&D on SiC/SiC composites is shifting toward the more pragmatic phase, i.e., industrialization of component manufactures and data-basing. In this paper, recent advances and issues in (1) development of component fabrication technology including joining and functional coating, e.g., a tungsten overcoat as a plasma facing barrier, (2) recent updates in characterization of non-irradiated properties, e.g., strength anisotropy and chemical compatibility with solid lithium-based ceramics and lead-lithium liquid metal breeders, and (3) irradiation effects are specifically reviewed. Importantly high-temperature neutron irradiation effects on microstructural evolution, thermal and electrical conductivities and mechanical properties including the fiber/matrix interfacial strength are specified under various irradiation conditions, indicating seemingly very minor influence on the composite performance in the design temperature range.

Mixed Convection Flow in Horizontal CVD Reactors

NASA Astrophysics Data System (ADS)

Chiu, Wilson K. S.; Richards, Cristy J.; Jaluria, Yogesh

1998-11-01

Increasing demands for high quality films and production rates are challenging current Chemical Vapor Deposition (CVD) technology. Since film quality and deposition rates are strongly dependent on gas flow and heat transfer (W.K.S. Chiu and Y. Jaluria, ASME HTD-Vol. 347, pp. 293-311, 1997.), process improvement is obtained through the study of mixed convection flow and temperature distribution in a CVD reactor. Experimental results are presented for a CVD chamber with a horizontal or inclined resistance heated susceptor. Vaporized glycol solution illuminated by a light sheet is used for flow visualization. Temperature measurements are obtained by inserting thermocouple probes into the gas stream or embedding probes into the reactor walls. Flow visualization and temperature measurements show predominantly two dimensional flow and temperature distributions along the streamwise direction under forced convection conditions. Natural convection dominates under large heating rates and low flow rates. Over the range of parameters studied, several distinct flow regimes, characterized by instability, separation, and turbulence, are evident. Different flow regimes alter the flow pattern and temperature distribution, and in consequence, significantly modify deposition rates and uniformity.

Deuterium desorption from ion-irradiated tantalum and effects on surface morphology

NASA Astrophysics Data System (ADS)

Novakowski, T. J.; Sundaram, A.; Tripathi, J. K.; Gonderman, S.; Hassanein, A.

2018-06-01

Compared to tungsten (W), tantalum (Ta) has shown superior resistance to helium (He)-induced surface morphology changes under fusion-relevant irradiation conditions. However, Ta is also expected to have a stronger interaction with hydrogen isotopes, potentially limiting its use as a plasma-facing material. Despite these concerns, detailed investigations on hydrogen irradiation effects on Ta are scarce. In this study, pristine and fuzzy (He+ ion-irradiated) Ta samples are irradiated with 120 eV deuterium (D) ions at various temperatures and examined with a combination of thermal desorption spectroscopy (TDS), scanning electron microscopy (SEM), and optical reflectivity. TDS reveals discrete D desorption temperatures at 660 and 760 K, corresponding to trapping energies of 1.82 and 2.11 eV, respectively. Although D is retained in Ta both in higher quantities and at higher temperatures compared to W, extreme surface temperatures expected in tokamak divertors may exceed these desorption temperatures and counteract retention. Furthermore, this study indicates that Ta is relatively resistant to adverse surface structuring under D+ ion irradiation. In fact, D+ is shown to prevent and suppress Ta fuzz formation in sequential D+/He+ ion irradiation experiments. While further investigations are needed to elucidate this behavior, these initial investigations show a strong potential for the use of Ta as a PFC material.

Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites.

PubMed

Hamze, Faeze; Ganjalikhan Nasab, Seyed Abdolreza; Eskandarizadeh, Ali; Shahravan, Arash; Akhavan Fard, Fatemeh; Sinaee, Neda

2018-01-01

Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey's HSD Post Hoc test for multiple comparisons ( α =0.05). The pulp temperature was significantly increased (repeated measures) during photo polymerization ( P =0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera ( P >0.05). Moreover, different composite materials and LCUs lead to similar outcomes ( P >0.05). Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature.

Fracture toughness evaluation of select advanced replacement alloys for LWR core internals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lizhen; Chen, Xiang

Life extension of the existing nuclear reactors imposes irradiation of high fluences to structural materials, resulting in significant challenges to the traditional reactor materials such as type 304 and 316 stainless steels. Advanced alloys with superior radiation resistance will increase safety margins, design flexibility, and economics for not only the life extension of the existing fleet but also new builds with advanced reactor designs. The Electric Power Research Institute (EPRI) teamed up with Department of Energy (DOE) to initiate the Advanced Radiation Resistant Materials (ARRM) program, aiming to develop and test degradation resistant alloys from current commercial alloy specifications bymore » 2021 to a new advanced alloy with superior degradation resistance in light water reactor (LWR)-relevant environments by 2024. Fracture toughness is one of the key engineering properties required for core internal materials. Together with other properties, which are being examined such as high-temperature steam oxidation resistance, radiation hardening, and irradiation-assisted stress corrosion cracking resistance, the alloys will be down-selected for neutron irradiation study and comprehensive post-irradiation examinations. According to the candidate alloys selected under the ARRM program, ductile fracture toughness of eight alloys was evaluated at room temperature and the LWR-relevant temperatures. The tested alloys include two ferritic alloys (Grade 92 and an oxide-dispersion-strengthened alloy 14YWT), two austenitic stainless steels (316L and 310), four Ni-base superalloys (718A, 725, 690, and X750). Alloy 316L and X750 are included as reference alloys for low- and high-strength alloys, respectively. Compact tension specimens in 0.25T and 0.2T were machined from the alloys in the T-L and R-L orientations according to the product forms of the alloys. This report summarizes the final results of the specimens tested and analyzed per ASTM Standard E1820. Unlike the ferritic alloys showing slight decreases (Grade 92) or significant decreases (14YWT) in fracture toughness at elevated temperatures, the fracture toughness of the austenitic stainless steels and Ni-base superalloys were not strongly dependent upon the test temperatures. The fracture toughness of the alloys at the LWR-relevant temperatures was estimated by averaging the toughness values within 250– 350°C, which suggested the fracture toughness of the alloys in a descending order as 316L (752±98 MPa√m), 310 (513±66 MPa√m), 718A (313±43 MPa√m), 690 (267±48 MPa√m), 725 (218±55 MPa√m), X750 (145±16 MPa√m), Grade 92 (112±12 MPa√m), and 14YWT (63±3 MPa√m). Tearing modulus of the alloys was analyzed in the meantime, which were not strongly dependent upon the test temperatures. The high-strength alloys 718A, 725, X750, and 14YWT had the lowest tearing modulus, ranging from ~45 to ~7. Alloy 690 exhibited the highest tearing modulus on the order of 450, followed by 316L and 310 on the order of 260. Grade 92 had a noticeably lower tearing modulus on the order of 70.« less

Laser cutting of Kevlar laminates and thermal stress formed at cutting sections

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Akhtar, S. S.

2012-02-01

Laser cutting of Kevlar laminates is carried out and thermal stress field developed in the cutting region is predicted using the finite element code. Temperature predictions are validated through the thermocouple data. The morphological changes in the cutting section are examined by incorporating optical and scanning electron microscopes. It is found that temperature predictions agree well with the thermocouple data. High values of von Mises stress are observed at the cutting edges and at the mid-thickness of the Kevlar laminate due to thermal compression formed in this region. The laser cut edges are free from whiskers; however, striation formation and some small sideways burning is observed at the kerf edges.

Pulp temperature increase during photo-activated disinfection (PAD) of periodontal pockets: an in vitro study.

PubMed

El Yazami, H; Zeinoun, Toni; Bou Saba, S; Lamard, L; Peremans, A; Limme, M; Geerts, S; Lamy, M; Nammour, S

2010-09-01

The capacity of photo-sensitizers, used in combination with laser light to kill micro-organisms has been demonstrated in different studies. Photo-activated disinfection (PAD) has been introduced in periodontology as an aid for disinfection of periodontal pockets. The aim of this study is to verify the harm for dental vitality of the use of PAD in periodontal pockets. Root canals of 24 freshly extracted human teeth where prepared using profiles up to a size of ISO #50 and filled with thermo-conductor paste. A silicon-based false gum was made in which a periodontal pocket was created and filled with photo-sensitizer phenothiazine chloride (phenothiazine-5-ium, 3.7-bis (dimethylamino)-, chloride). The external root surface was irradiated during 60 s with a 660-nm diode laser (output power: 20 mW; power density: 0.090 W/cm(2); Energy density: 5.46 J/cm(2)) using a periodontal tip with a diameter of 1 mm and a length of 7 mm. Temperatures were recorded inside the root canal using a thermocouple. Measurements were recorded every second, starting at 10 s before lasering, during the irradiation and were continued for 150 s after the end of irradiation, and six measurements were done per tooth. An average temperature increase of 0.48 +/- 0.11 degrees C was recorded. Our results demonstrated that pulp temperature increase was lower than 3 degrees C, which is considered to be harmless for pulp injury. Regarding pulp temperature increase, the use of PAD for disinfection of periodontal pockets can be considered as a safe procedure for dental vitality.

Scanning thermal microscopy based on a quartz tuning fork and a micro-thermocouple in active mode (2ω method).

PubMed

Bontempi, Alexia; Nguyen, Tran Phong; Salut, Roland; Thiery, Laurent; Teyssieux, Damien; Vairac, Pascal

2016-06-01

A novel probe for scanning thermal microscope using a micro-thermocouple probe placed on a Quartz Tuning Fork (QTF) is presented. Instead of using an external deflection with a cantilever beam for contact detection, an original combination of piezoelectric resonator and thermal probe is employed. Due to a non-contact photothermal excitation principle, the high quality factor of the QTF allows the probe-to-surface contact detection. Topographic and thermal scanning images obtained on a specific sample points out the interest of our system as an alternative to cantilevered resistive probe systems which are the most spread.

Scanning thermal microscopy based on a quartz tuning fork and a micro-thermocouple in active mode (2ω method)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bontempi, Alexia; Nguyen, Tran Phong; Salut, Roland

A novel probe for scanning thermal microscope using a micro-thermocouple probe placed on a Quartz Tuning Fork (QTF) is presented. Instead of using an external deflection with a cantilever beam for contact detection, an original combination of piezoelectric resonator and thermal probe is employed. Due to a non-contact photothermal excitation principle, the high quality factor of the QTF allows the probe-to-surface contact detection. Topographic and thermal scanning images obtained on a specific sample points out the interest of our system as an alternative to cantilevered resistive probe systems which are the most spread.

Three-Wire Thermocouple: Frequency Response in Constant Flow

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1995-01-01

Theory and experimental measurements are compared with a novel three-wire thermocouple. Signals from three wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three-wire thermocouple requires no compensation for omega less than or equal to 5(omega(sub 1)), where omega(sub 1) is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two-wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter.

Three-wire Thermocouple: Frequency Response in Constant Flow

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1995-01-01

Theory and experimental measurements are compared with a novel three-wire thermocouple. Signals from three wires of unequal diameters arc recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three-wire thermocouple requires no compensation for omega less than or equal to 5(sub omega1), where omega, is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two-wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter.

Thermoregulatory control of finger blood flow

NASA Technical Reports Server (NTRS)

Wenger, C. B.; Roberts, M. F.; Nadel, E. R.; Stolwijk, J. A. J.

1975-01-01

In the present experiment, exercise was used to vary internal temperature and ambient air heat control was used to vary skin temperature. Finger temperature was fixed at about 35.7 C. Esophageal temperature was measured with a thermocouple at the level of the left atrium, and mean skin temperature was calculated from a weighted mean of thermocouple temperatures at different skin sites. Finger blood flow was measured by electrocapacitance plethysmography. An equation in these quantities is given which accounts for the data garnered.

Temperature, illumination and fluence dependence of current and voltage in electron irradiated solar cells

NASA Technical Reports Server (NTRS)

Obenschain, A. F.; Faith, T. J.

1973-01-01

Emperical equations have been derived from measurements of solar cell photovoltaic characteristics relating light generated current, IL, and open circuit voltage, VO, to cell temperature, T, intensity of illumination, W, and 1 Mev electron fluence, phi both 2 ohm-cm and 10 ohm-cm cells were tested. The temperature dependency of IL is similar for both resistivities at 140mw/sq cm; at high temperature the coefficient varies with fluence as phi 0.18, while at low temperatures the coefficient is relatively independent of fluence. Fluence dependent degration causes a decrease in IL at a rate proportional to phi 0.153 for both resistivities. At all intensities other than 560 mw/sq cm, a linear dependence of IL on illumination was found. The temperature coefficient of voltage was, to a good approximation, independent of both temperature and illumination for both resistivities. Illumination dependence of VOC was logarithmic, while the decrease with fluence of VOC varied as phi 0.25 for both resistivities.

Investigations on neutron irradiated 3D carbon fibre reinforced carbon composite material

NASA Astrophysics Data System (ADS)

Venugopalan, Ramani; Alur, V. D.; Patra, A. K.; Acharya, R.; Srivastava, D.

2018-04-01

As against conventional graphite materials carbon-carbon (C/C) composite materials are now being contemplated as the promising candidate materials for the high temperature and fusion reactor owing to their high thermal conductivity and high thermal resistance, better mechanical/thermal properties and irradiation stability. The current need is for focused research on novel carbon materials for future new generation nuclear reactors. The advantage of carbon-carbon composite is that the microstructure and the properties can be tailor made. The present study encompasses the irradiation of 3D carbon composite prepared by reinforcement using PAN carbon fibers for nuclear application. The carbon fiber reinforced composite was subjected to neutron irradiation in the research reactor DHRUVA. The irradiated samples were characterized by Differential Scanning Calorimetry (DSC), small angle neutron scattering (SANS), XRD and Raman spectroscopy. The DSC scans were taken in argon atmosphere under a linear heating program. The scanning was carried out at temperature range from 30 °C to 700 °C at different heating rates in argon atmosphere along with reference as unirradiated carbon composite. The Wigner energy spectrum of irradiated composite showed two peaks corresponding to 200 °C and 600 °C. The stored energy data for the samples were in the range 110-170 J/g for temperature ranging from 30 °C to 700 °C. The Wigner energy spectrum of irradiated carbon composite did not indicate spontaneous temperature rise during thermal annealing. Small angle neutron scattering (SANS) experiments have been carried out to investigate neutron irradiation induced changes in porosity of the composite samples. SANS data were recorded in the scattering wave vector range of 0.17 nm-1 to 3.5 nm-1. Comparison of SANS profiles of irradiated and unirradiated samples indicates significant change in pore morphology. Pore size distributions of the samples follow power law size distribution with different exponent. Narrowing of SANS profile of the irradiated sample indicates creation of significant number of larger pores due to neutron irradiation.

AGR-1 Irradiation Test Final As-Run Report, Rev. 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collin, Blaise P.

2015-01-01

This document presents the as-run analysis of the AGR-1 irradiation experiment. AGR-1 is the first of eight planned irradiations for the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program. Funding for this program is provided by the US Department of Energy (DOE) as part of the Next-Generation Nuclear Plant (NGNP) project. The objectives of the AGR-1 experiment are: 1. To gain experience with multi-capsule test train design, fabrication, and operation with the intent to reduce the probability of capsule or test train failure in subsequent irradiation tests. 2. To irradiate fuel produced in conjunction with the AGR fuel processmore » development effort. 3. To provide data that will support the development of an understanding of the relationship between fuel fabrication processes, fuel product properties, and irradiation performance. In order to achieve the test objectives, the AGR-1 experiment was irradiated in the B-10 position of the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL) for a total duration of 620 effective full power days of irradiation. Irradiation began on December 24, 2006 and ended on November 6, 2009 spanning 13 ATR cycles and approximately three calendar years. The test contained six independently controlled and monitored capsules. Each capsule contained 12 compacts of a single type, or variant, of the AGR coated fuel. No fuel particles failed during the AGR-1 irradiation. Final burnup values on a per compact basis ranged from 11.5 to 19.6 %FIMA, while fast fluence values ranged from 2.21 to 4.39 x 10 25 n/m 2 (E >0.18 MeV). We’ll say something here about temperatures once thermal recalc is done. Thermocouples performed well, failing at a lower rate than expected. At the end of the irradiation, nine of the originally-planned 19 TCs were considered functional. Fission product release-to-birth (R/B) ratios were quite low. In most capsules, R/B values at the end of the irradiation were at or below 10 -7 with only one capsule significantly exceeding this value. A maximum R/B of around 2 x 10 -7 was reached at the end of the irradiation in Capsule 5. Several shakedown issues were encountered and resolved during the first three cycles. These include the repair of minor gas line leaks; repair of faulty gas line valves; the need to position moisture monitors in regions of low radiation fields for proper functioning; the enforcement of proper on-line data storage and backup, the need to monitor thermocouple performance, correcting for detector spectral gain shift, and a change in the mass flow rate range of the neon flow controllers.« less

Etching of enamel for direct bonding with a thulium fiber laser

NASA Astrophysics Data System (ADS)

Kabaş Sarp, Ayşe S.; Gülsoy, Murat

2011-03-01

Background: Laser etching of enamel for direct bonding can decrease the risk of surface enamel loss and demineralization which are the adverse effects of acid etching technique. However, in excess of +5.5°C can cause irreversible pulpal responses. In this study, a 1940- nm Thulium Fiber Laser in CW mode was used for laser etching. Aim: Determination of the suitable Laser parameters of enamel surface etching for direct bonding of ceramic brackets and keeping that intrapulpal temperature changes below the threshold value. Material and Method: Polycrystalline ceramic orthodontic brackets were bonded on bovine teeth by using 2 different kinds of etching techniques: Acid and Laser Etching. In addition to these 3 etched groups, there was also a group which was bonded without etching. Brackets were debonded with a material testing machine. Breaking time and the load at the breaking point were measured. Intrapulpal temperature changes were recorded by a K-type Thermocouple. For all laser groups, intrapulpal temperature rise was below the threshold value of 5.5°C. Results and Conclusion: Acid-etched group ( 11.73 MPa) significantly required more debonding force than 3- second- irradiated ( 5.03 MPa) and non-etched groups ( 3.4 MPa) but the results of acid etched group and 4- second- irradiated group (7.5 MPa) showed no significant difference. Moreover, 4- second irradiated group was over the minimum acceptable value for clinical use. Also, 3- second lasing caused a significant reduction in time according to acid-etch group. As a result, 1940- nm laser irradiation is a promising method for laser etching.

Predicting the Behavior of Asphalt Concrete Pavements in Seasonal Frost Areas Using Nondestructive Techniques

DTIC Science & Technology

1990-11-01

and psychrometers : the loca- cm-diameter wooden dowel approximately 122 cm in tion of these gauges is shown in Figure 16. The length, with 4.0-mm holes...thermocouple psychrometers were the third Dowel set of sensors used. A detailed description of these sensors can be found in a paper by Brown and...Figure 19. Freezing of test sections. in resistance with temperature in TS 2. Major changes psychrometers were not evaluated for this report. These in

Microstructure chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

DOE PAGES

Sun, C.; Kirk, M.; Li, M.; ...

2015-06-14

Nickel superalloys with cubic L12 structured γ' (Ni 3(Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger γ' precipitates, ~450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. Under heavy ion irradiation at room temperature, the submicron-sized γ' precipitates were fully disordered at ~0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical propertiesmore » of the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. Moreover, the generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized γ' precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between γ' precipitates and matrix (<18 dpa). As a result, controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.« less

Dynamic gas temperature measurement system, volume 1

NASA Technical Reports Server (NTRS)

Elmore, D. L.; Robinson, W. W.; Watkins, W. B.

1983-01-01

A gas temperature measurement system with compensated frequency response of 1 kHz and capability to operate in the exhaust of a gas turbine engine combustor was developed. A review of available technologies which could attain this objective was done. The most promising method was identified as a two wire thermocouple, with a compensation method based on the responses of the two different diameter thermocouples to the fluctuating gas temperature field. In a detailed design of the probe, transient conduction effects were identified as significant. A compensation scheme was derived to include the effects of gas convection and wire conduction. The two wire thermocouple concept was tested in a laboratory burner exhaust to temperatures of about 3000 F and in a gas turbine engine to combustor exhaust temperatures of about 2400 F. Uncompensated and compensated waveforms and compensation spectra are presented.

Synergies Between ' and Cavity Formation in HT-9 Following High Dose Neutron Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Kevin G.; Parish, Chad M.; Saleh, Tarik A.

Candidate cladding materials for advanced nuclear power reactors including fast reactor designs require materials capable of withstanding high dose neutron irradiation at elevated temperatures. One candidate material, HT-9, through various research programs have demonstrated the ability to withstand significant swelling and other radiation-induced degradation mechanisms in the high dose regime (>50 displacements per atom, dpa) at elevated temperatures (>300 C). Here, high efficiency multi-dimensional scanning transmission electron microscopy (STEM) acquisition with the aid of a three-dimensional (3D) reconstruction and modeling technique is used to probe the microstructural features that contribute to the exceptional swelling resistance of HT-9. In particular, themore » synergies between ' and fine-scale and moderate-scale cavity formation is investigated.« less

Novel Multisensor Probe for Monitoring Bladder Temperature During Locoregional Chemohyperthermia for Nonmuscle-Invasive Bladder Cancer: Technical Feasibility Study

PubMed Central

Geijsen, Debby E.; Zum Vörde Sive Vörding, Paul J.; Schooneveldt, Gerben; Sijbrands, Jan; Hulshof, Maarten C.; de la Rosette, Jean; de Reijke, Theo M.; Crezee, Hans

2013-01-01

Abstract Background and Purpose: The effectiveness of locoregional hyperthermia combined with intravesical instillation of mitomycin C to reduce the risk of recurrence and progression of intermediate- and high-risk nonmuscle-invasive bladder cancer is currently investigated in clinical trials. Clinically effective locoregional hyperthermia delivery necessitates adequate thermal dosimetry; thus, optimal thermometry methods are needed to monitor accurately the temperature distribution throughout the bladder wall. The aim of the study was to evaluate the technical feasibility of a novel intravesical device (multi-sensor probe) developed to monitor the local bladder wall temperatures during loco-regional C-HT. Materials and Methods: A multisensor thermocouple probe was designed for deployment in the human bladder, using special sensors to cover the bladder wall in different directions. The deployment of the thermocouples against the bladder wall was evaluated with visual, endoscopic, and CT imaging in bladder phantoms, porcine models, and human bladders obtained from obduction for bladder volumes and different deployment sizes of the probe. Finally, porcine bladders were embedded in a phantom and subjected to locoregional heating to compare probe temperatures with additional thermometry inside and outside the bladder wall. Results: The 7.5 cm thermocouple probe yielded optimal bladder wall contact, adapting to different bladder volumes. Temperature monitoring was shown to be accurate and representative for the actual bladder wall temperature. Conclusions: Use of this novel multisensor probe could yield a more accurate monitoring of the bladder wall temperature during locoregional chemohyperthermia. PMID:24112045

NEET Enhanced Micro-Pocket Fission Detector for High Temperature Reactors - FY16 Status Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unruh, Troy; Reichenberger, Michael; Stevenson, Sarah

2016-09-01

A collaboration between the Idaho National Laboratory (INL), the Kansas State University (KSU), and the French Atomic Energy Agency, Commissariat à l'Énergie Atomique et aux Energies Alternatives, (CEA), has been initiated by the Nuclear Energy Enabling Technologies (NEET) Advanced Sensors and Instrumentation (ASI) program for developing and testing High Temperature Micro-Pocket Fission Detectors (HT MPFD), which are compact fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package for temperatures up to 800 °C. The MPFD technology utilizes a small, multi-purpose, robust, in-core fission chambers and thermocouple. As discussed within this report,more » the small size, variable sensitivity, and increased accuracy of the MPFD technology represent a revolutionary improvement over current methods used to support irradiations in US Material Test Reactors (MTRs). Previous research conducted through NEET ASI1-3 has shown that the MPFD technology could be made robust and was successfully tested in a reactor core. This new project will further the MPFD technology for higher temperature regimes and other reactor applications by developing a HT MPFD suitable for temperatures up to 800 °C. This report summarizes the research progress for year two of this three year project. Highlights from research accomplishments include: • Continuation of a joint collaboration between INL, KSU, and CEA. Note that CEA is participating at their own expense because of interest in this unique new sensor. • An updated parallel wire HT MPFD design was developed. • Program support for HT MPFD deployments was given to Accident Tolerant Fuels (ATF) and Advanced Gas-cooled Reactor (AGR) irradiation test programs. • Quality approved materials for HT MPFD construction were procured by irradiation test programs for upcoming deployments. • KSU improved and performed electrical contact and fissile material plating. • KSU delivered fissile HT MPFD parts to INL for final construction of HT MPFD prototype. • A prototype HT MPFD was constructed and analyzed at INL. • The HT MPFD has been modeled in MCNP to optimize the amount of fissile material deposition. • The HT MPFD has been modeled in MCNP to optimize the sensor location in the irradiation test. • The fissile material deposition is undergoing independent verifications. • Detector amplifier electronics have been revised and tested by KSU. • Several project meetings were held at INL and KSU to discuss the roles and responsibilities between INL, KSU, and CEA for development and deployment of the HT MPFDs. As documented in this report, FY16 funding has allowed the project to meet year two planned accomplishments to develop a HT MPFD. In addition, the accomplishments of this project have attracted independent funding from other Department of Energy Office of Nuclear Energy (DOE-NE) programs for MTR irradiations of the MPFD technology. These are significant opportunities for this NEET Enhanced Micro-Pocket Fission Detector for High Temperature Reactors project because the irradiation expense of these experiments could not be included in the original project scope.« less

Thermal Conductivity Change Kinetics of Ceramic Thermal Barrier Coatings Determined by the Steady-State Laser Heat Flux Technique

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2000-01-01

A steady-state laser heat flux technique has been developed at the NASA Glenn Research Center at Lewis Field to obtain critical thermal conductivity data of ceramic thermal barrier coatings under the temperature and thermal gradients that are realistically expected to be encountered in advanced engine systems. In this study, thermal conductivity change kinetics of a plasma-sprayed, 254-mm-thick ZrO2-8 wt % Y2O3 ceramic coating were obtained at high temperatures. During the testing, the temperature gradients across the coating system were carefully measured by the surface and back pyrometers and an embedded miniature thermocouple in the substrate. The actual heat flux passing through the coating system was determined from the metal substrate temperature drop (measured by the embedded miniature thermocouple and the back pyrometer) combined with one-dimensional heat transfer models.

Temperature changes in dental implants following exposure to hot substances in an ex vivo model.

PubMed

Feuerstein, Osnat; Zeichner, Kobi; Imbari, Chen; Ormianer, Zeev; Samet, Nachum; Weiss, Ervin I

2008-06-01

The habitual consumption of extremely hot foods and beverages may affect implant treatment modality. Our objectives were to: (i) establish the maximum temperature produced intra-orally while consuming very hot substances and (ii) use these values in an ex vivo model to assess the temperature changes along the implant-bone interface. Temperatures were measured using thermocouples linked to a computer. The thermocouple electrodes were attached to the tooth-gum interface of the interproximal areas in 14 volunteers during consumption of extremely hot foods and beverages. The in vivo measured temperature values obtained were used in an ex vivo model of a bovine mandible block with an implant and with an assembled abutment. Temperatures were measured by thermocouple electrodes attached to five locations, three of them along the implant-bone interface. During consumption of a hot beverage, a maximum temperature of up to 76.3 degrees C was recorded, and a calculated extreme intra-oral temperature of 61.4 degrees C was established. The ex vivo model showed a high correlation between the temperature measured at the abutment and that measured at the abutment-implant interface and inside the implant, reaching maximum temperatures close to 60 degrees C. At the mid-implant-bone and apical implant-bone interfaces, the maximum temperatures measured were 43.3 and 42 degrees C, respectively. The maximum temperatures measured at the implant-bone interfaces reached the temperature threshold of transient changes in bone (42 degrees C). The results of this study support the notion that intra-oral temperatures, developed during the consumption of very hot substances, may be capable of damaging peri-implant tissues.

Laboratory investigation of the efficacy of holmium:YAG laser irradiation in removing intracanal debris

NASA Astrophysics Data System (ADS)

Nuebler-Moritz, Michael; Gutknecht, Norbert; Sailer, Hermann F.; Hering, Peter; Prettl, Wilhelm

1997-05-01

Current endodontic therapy involves debridement and disinfection of the root canal by means of mechanical instrumentation and chemical irrigation. However, several studies have shown that these techniques fail to achieve complete cleansing. Recently, lasers have been suggested for use within root canals. This study was conducted to determine the efficacy of Holmium:YAG laser irradiation in removing intracanal debris and smear layer. Root canal surfaces of freshly-extracted human teeth were exposed to pulsed Ho:YAG laser radiation. Subsequently, laser induced structural changes were investigated using scanning electron microscopy. Temperature measurements during irradiation were performed by means of thermocouples. The result of this survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment modalities. However, limitations exist with regard to circumscribed and well-quantified irradiation of root canal surfaces, due to the lack of perpendicular delivery of the laser beam. Additional studies will be required to develop suitable optical transmission systems, in order to achieve complete cleansing and to avoid damage to the periradicular tissues, respectively.

In vitro study of heat production during power reduction of equine mandibular teeth.

PubMed

Allen, Martin L; Baker, Gordon J; Freeman, David E; Holmes, Kenneth R; Marretta, Sandra Manfra; Scoggins, R Dean; Constable, Peter

2004-04-01

To measure the amount of heat generated during 3 methods of equine dental reduction with power instruments. In vitro study. 30 premolar and molar teeth removed from mandibles of 8 equine heads collected at an abbatoir. 38-gauge copper-constantan thermocouples were inserted into the lingual side of each tooth 15 mm (proximal) and 25 mm (distal) from the occlusal surface, at a depth of 5 mm, which placed the tip close to the pulp chamber. Group-NC1 (n = 10) teeth were ground for 1 minute without coolant, group-NC2 (10) teeth were ground for 2 minutes without coolant, and group-C2 (10) teeth were ground for 2 minutes with water for coolant. Mean temperature increase was 1.2 degrees C at the distal thermocouple and 6.6 degrees C at the proximal thermocouple for group-NC1 teeth, 4.1 degrees C at the distal thermocouple and 24.3 degrees C at the proximal thermocouple for group-NC2 teeth, and 0.8 degrees C at the distal thermocouple and -0.1 degrees C at the proximal thermocouple for group-C2 teeth. In general, an increase of 5 degrees C in human teeth is considered the maximum increase before there is permanent damage to tooth pulp. In group-NC2 teeth, temperature increased above this limit by several degrees, whereas in group-C2 teeth, there was little or no temperature increase. Our results suggest that major reduction of equine teeth by use of power instruments causes thermal changes that may cause irreversible pulp damage unless water cooling is used.

Accurate temperature measurement by temperature field analysis in diamond anvil cell for thermal transport study of matter under high pressures

NASA Astrophysics Data System (ADS)

Yue, Donghui; Ji, Tingting; Qin, Tianru; Wang, Jia; Liu, Cailong; Jiao, Hui; Zhao, Lin; Han, Yonghao; Gao, Chunxiao

2018-02-01

The study on the thermal transport properties of matter under high pressure is important but is hard to fulfill in a diamond anvil cell (DAC) because the accurate measurement of the temperature gradient within the sample of DAC is very difficult. In most cases, the sample temperature can be read accurately from the thermocouples that are directly attached to the lateral edges of diamond anvils because both the sample and diamond anvils can be uniformly heated up to a given temperature. But for the thermal transport property studies in DAC, an artificial temperature distribution along the compression axis is a prerequisite. Obviously, the temperature of the top or bottom surface of the sample cannot be substituted by that of diamond anvils although diamond anvils can be considered as a good medium for heat conduction. With temperature field simulation by finite element analysis, it is found that big measurement errors can occur and are fatal to the correct analysis of thermal transport properties of materials. Thus, a method of combining both the four-thermocouple configuration and temperature field analysis is presented for the accurate temperature distribution measurement in DAC, which is based on the single-function relationship between temperature distribution and sample thermal conductivity.

Temperature measurement and damage detection in concrete beams exposed to fire using PPP-BOTDA based fiber optic sensors

NASA Astrophysics Data System (ADS)

Bao, Yi; Hoehler, Matthew S.; Smith, Christopher M.; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, Brillouin scattering-based distributed fiber optic sensor is implemented to measure temperature distributions and detect cracks in concrete structures subjected to fire for the first time. A telecommunication-grade optical fiber is characterized as a high temperature sensor with pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA), and implemented to measure spatially-distributed temperatures in reinforced concrete beams in fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9%. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

Artefacts in intracavitary temperature measurements during regional hyperthermia.

PubMed

Kok, H P; Van den Berg, C A T; Van Haaren, P M A; Crezee, J

2007-09-07

For adequate hyperthermia treatments, reliable temperature information during treatment is essential. During regional hyperthermia, temperature information is preferably obtained non-invasively from intracavitary or intraluminal measurements to avoid implant risks for the patient. However, for intracavitary or intraluminal thermometry optimal tissue contact is less natural as for invasive thermometry. In this study, the reliability of intraluminal/intracavitary measurements was examined in phantom experiments and in a numerical model for various extents of thermal contact between thermometry and the surroundings. Both thermocouple probes and fibre optic probes were investigated. Temperature rises after a 30 s power pulse of the 70 MHz AMC-4 hyperthermia system were measured in a tissue-equivalent phantom using a multisensor thermocouple probe placed centrally in a hollow tube. The tube was filled with (1) air, (2) distilled water or (3) saline solution that mimics the properties of tissue, simulating situations with (1) bad thermal contact and no power dissipation in the tube, (2) good thermal contact but no power dissipation or (3) good thermal contact and tissue representative power dissipation. For numerical simulations, a cylindrical symmetric model of a thermocouple probe or a fibre optic probe in a cavity was developed. The cavity was modelled as air, distilled water or saline solution. A generalised E-Field distribution was assumed, resulting in a power deposition. With this power deposition, the temperature rise after a 30 s power pulse was calculated. When thermal contact was bad (1), both phantom measurements and simulations with a thermocouple probe showed very high temperature rises (>0.5 degrees C), which are artefacts due to self-heating of the thermocouple probe, since no power is dissipated in air. Simulations with a fibre optic probe showed almost no temperature rise when the cavity was filled with air. When thermal contact was good, but no power was dissipated in the tube (2), artefacts due to self-heating were not significant and the observed temperature rises were very low ( approximately 0-0.1 degrees C). For the situation, with tissue representative power dissipation (3), a temperature rise of approximately 0.23 degrees C was observed for both measurements and simulations. A clinical example of a regional hyperthermia treatment of a patient with a cervix uteri carcinoma showed that the artefacts observed in the case of bad thermal contact also affect the steady-state temperature measurements. Good tissue contact must be assured for reliable intraluminal or intracavitary measurements.

Experimental study on occupant's thermal responses under the non-uniform conditions in vehicle cabin during the heating period

NASA Astrophysics Data System (ADS)

Zhang, Wencan; Chen, Jiqing; Lan, Fengchong

2014-03-01

The existing investigations on thermal comfort mostly focus on the thermal environment conditions, especially of the air-flow field and the temperature distributions in vehicle cabin. Less attention appears to direct to the thermal comfort or thermal sensation of occupants, even to the relationship between thermal conditions and thermal sensation. In this paper, a series of experiments were designed and conducted for understanding the non-uniform conditions and the occupant's thermal responses in vehicle cabin during the heating period. To accurately assess the transient temperature distribution in cabin in common daily condition, the air temperature at a number of positions is measured in a full size vehicle cabin under natural winter environment in South China by using a discrete thermocouples network. The occupant body is divided into nine segments, the skin temperature at each segment and the occupant's local thermal sensation at the head, body, upper limb and lower limb are monitored continuously. The skin temperature is observed by using a discrete thermocouples network, and the local thermal sensation is evaluated by using a seven-point thermal comfort survey questionnaire proposed by American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc(ASHRAE) Standard. The relationship between the skin temperature and the thermal sensation is discussed and regressed by statistics method. The results show that the interior air temperature is highly non-uniform over the vehicle cabin. The locations where the occupants sit have a significant effect on the occupant's thermal responses, including the skin temperature and the thermal sensation. The skin temperature and thermal sensation are quite different between body segments due to the effect of non-uniform conditions, clothing resistance, and the human thermal regulating system. A quantitative relationship between the thermal sensation and the skin temperature at each body segment of occupant in real life traffic is presented. The investigation result indicates that the skin temperature is a robust index to evaluate the thermal sensation. Applying the skin temperature to designing and controlling parameters of the heating, ventilation and air conditioning(HVAC) system may benefit the thermal comfort and reducing energy consumption.

A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han

The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This paper aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide amore » comparative assessment of their high-temperature structural performance. The K JQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Finally, irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.« less

A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

DOE PAGES

Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; ...

2016-12-07

The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This paper aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide amore » comparative assessment of their high-temperature structural performance. The K JQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Finally, irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.« less

A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

NASA Astrophysics Data System (ADS)

Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

2017-02-01

The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This study aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.

Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings

NASA Astrophysics Data System (ADS)

Li, Bo; Jin, Yan; Yao, Jianhua; Li, Zhihong; Zhang, Qunli; Zhang, Xin

2018-03-01

Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.

Implications of using thermocouple thermometry in 27 MHz capacitively coupled interstitial hyperthermia.

PubMed

Crezee, J; van der Koijk, J F; Kaatee, R S; Lagendijk, J J

1997-04-01

The 27 MHz Multi Electrode Current Source (MECS) interstitial hyperthermia system uses segmented electrodes, 10-20 mm long, to steer the 3D power deposition. This power control at a scale of 1-2 cm requires detailed and accurate temperature feedback data. To this end seven-point thermocouples are integrated into the probes. The aim of this work was to evaluate the feasibility and reliability of integrated thermometry in the 27 MHz MECS system, with special attention to the interference between electrode and thermometry and its effect on system performance. We investigated the impact of a seven-sensor thermocouple probe (outer diameter 150 microns) on the apparent impedance and power output of a 20 mm dual electrode (O.D. 1.5 mm) in a polyethylene catheter in a muscle equivalent medium (sigma 1 = 0.6 S m-1). The cross coupling between electrode and thermocouple was found to be small (1-2 pF) and to cause no problems in the dual-electrode mode, and only minimal problems in the single-electrode mode. Power loss into the thermometry system can be prevented using simple filters. The temperature readings are reliable and representative of the actual tissue temperature around the electrode. Self-heating effects, occurring in some catheter materials, are eliminated by sampling the temperature after a short power-off interval. We conclude that integrated thermocouple thermometry is compatible with 27 MHz capacitively coupled interstitial hyperthermia. The performance of the system is not affected and the temperatures measured are a reliable indication of the maximum tissue temperatures.

Thin film ceramic thermocouples

NASA Technical Reports Server (NTRS)

Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

2011-01-01

A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

Non-contact temperature Raman measurement in YSZ and alumina ceramics

NASA Astrophysics Data System (ADS)

Thapa, Juddha; Chorpening, Benjamin T.; Buric, Michael P.

2018-02-01

Yttria-stabilized zirconia (YSZ: ZrO2 + Y2O3) and alumina (Al2O3) are widely used in high-temperature applications due to their high-temperature stability, low thermal conductivity, and chemical inertness. Alumina is used extensively in engineered ceramic applications such as furnace tubes and thermocouple protection tubes, while YSZ is commonly used in thermal barrier coatings on turbine blades. Because they are already often found in high temperature and combustion applications, these two substances have been compared as candidates for Raman thermometry in high-temperature energy-related applications. Both ceramics were used with as-received rough surfaces, i.e., without polishing or modification. This closely approximates surface conditions in practical high-temperature situations. A single-line argon ion laser at 488nm was used to excite the materials inside a cylindrical furnace while measuring Raman spectra with a fixed-grating spectrometer. The shift in the peak positions of the most intense A1g peak at 418cm-1 (room temperature position) of alumina ceramic and relatively more symmetric Eg peak at 470cm-1 (room temperature position) of YSZ were measured and reported along with a thermocouple-derived reference temperature up to about 1000°C. This study showed that alumina and YSZ ceramics can be used in high-temperature Raman thermometry with an accuracy of 4.54°C and 10.5°C average standard deviations respectively over the range of about 1000°C. We hope that this result will guide future researchers in selecting materials and utilizing Raman non-contact temperature measurements in harsh environments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.

Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M 23C 6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

Isolation of Radiation-Resistant Bacteria from Mars Analog Antarctic Dry Valleys by Preselection, and the Correlation between Radiation and Desiccation Resistance.

PubMed

Musilova, Michaela; Wright, Gary; Ward, John M; Dartnell, Lewis R

2015-12-01

Extreme radiation-resistant microorganisms can survive doses of ionizing radiation far greater than are present in the natural environment. Radiation resistance is believed to be an incidental adaptation to desiccation resistance, as both hazards cause similar cellular damage. Desert soils are, therefore, promising targets to prospect for new radiation-resistant strains. This is the first study to isolate radiation-resistant microbes by using gamma-ray exposure preselection from the extreme cold desert of the Antarctic Dry Valleys (a martian surface analogue). Halomonads, identified by 16S rRNA gene sequencing, were the most numerous survivors of the highest irradiation exposures. They were studied here for the first time for both their desiccation and irradiation survival characteristics. In addition, the association between desiccation and radiation resistance has not been investigated quantitatively before for a broad diversity of microorganisms. Thus, a meta-analysis of scientific literature was conducted to gather a larger data set. A strong correlation was found between desiccation and radiation resistance, indicating that an increase in the desiccation resistance of 5 days corresponds to an increase in the room-temperature irradiation survival of 1 kGy. Irradiation at -79°C (representative of average martian surface temperatures) increases the microbial radiation resistance 9-fold. Consequently, the survival of the cold-, desiccation-, and radiation-resistant organisms isolated here has implications for the potential habitability of dormant or cryopreserved life on Mars. Extremophiles-Halomonas sp.-Antarctica-Mars-Ionizing radiation-Cosmic rays.

Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gussev, Maxim N.; Field, Kevin G.

High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAlmore » alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed the non-welded specimens to exhibit strain-induced softening (decrease in the true stress level) with increasing plastic strain during tensile testing. Fracture for the weldments was found to occur exclusively within the fusion zone. The mechanical performance of the weldment was speculated to be directly linked to variances in the radiation-induced microstructure including the formation of dislocation loops and precipitation of the Cr-rich α' phase. The localized microstructural variation within the weldments, including grain size, was determined to play a significant role in the radiation-induced microstructure. The results summarized within highlight the need for additional data on the radiation tolerance of weldments as the mechanical performance of the fusion zone was shown to be the limiting factor in the overall performance of the weldments.« less

Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites

PubMed Central

Hamze, Faeze; Ganjalikhan Nasab, Seyed Abdolreza; Eskandarizadeh, Ali; Shahravan, Arash; Akhavan Fard, Fatemeh; Sinaee, Neda

2018-01-01

Introduction: Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. Methods and Materials: A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey’s HSD Post Hoc test for multiple comparisons (α=0.05). Results: The pulp temperature was significantly increased (repeated measures) during photo polymerization (P=0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera (P>0.05). Moreover, different composite materials and LCUs lead to similar outcomes (P>0.05). Conclusion: Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature. PMID:29707014

Program Processes Thermocouple Readings

NASA Technical Reports Server (NTRS)

Quave, Christine A.; Nail, William, III

1995-01-01

Digital Signal Processor for Thermocouples (DART) computer program implements precise and fast method of converting voltage to temperature for large-temperature-range thermocouple applications. Written using LabVIEW software. DART available only as object code for use on Macintosh II FX or higher-series computers running System 7.0 or later and IBM PC-series and compatible computers running Microsoft Windows 3.1. Macintosh version of DART (SSC-00032) requires LabVIEW 2.2.1 or 3.0 for execution. IBM PC version (SSC-00031) requires LabVIEW 3.0 for Windows 3.1. LabVIEW software product of National Instruments and not included with program.

Solar energy control system. [temperature measurement

NASA Technical Reports Server (NTRS)

Currie, J. R. (Inventor)

1981-01-01

A solar energy control system for a hot air type solar energy heating system wherein thermocouples are arranged to sense the temperature of a solar collector, a space to be heated, and a top and bottom of a heat storage unit is disclosed. Pertinent thermocouples are differentially connected together, and these are employed to effect the operation of dampers, a fan, and an auxiliary heat source. In accomplishing this, the differential outputs from the thermocouples are amplified by a single amplifier by multiplexing techniques. Additionally, the amplifier is corrected as to offset by including as one multiplex channel a common reference signal.

SUBCOOLING DETECTOR

DOEpatents

McCann, J.A.

1963-12-17

A system for detecting and measuring directly the subcooling margin in a liquid bulk coolant is described. A thermocouple sensor is electrically heated, and a small amount of nearly stagnant bulk coolant is heated to the boiling point by this heated thermocouple. The sequential measurement of the original ambient temperature, zeroing out this ambient temperature, and then measuring the boiling temperature of the coolant permits direct determination of the subcooling margin of the ambient liquid. (AEC)

γ-rays irradiation effects on dielectric properties of Ti/Au/GaAsN Schottky diodes with 1.2%N

NASA Astrophysics Data System (ADS)

Teffahi, A.; Hamri, D.; Djeghlouf, A.; Abboun Abid, M.; Saidane, A.; Al Saqri, N.; Felix, J. F.; Henini, M.

2018-06-01

Dielectric properties of As grown and irradiated Ti /Au/GaAsN Schottky diodes with 1.2%N are investigated using capacitance/conductance-voltage measurements in 90-290 K temperature range and 50-2000 kHz frequency range. Extracted parameters are interface state density, series resistance, dielectric constant, dielectric loss, tangent loss and ac conductivity. It is shown that exposure to γ-rays irradiation leads to reduction in effective trap density believed to result from radiation-induced traps annulations. An increase in series resistance is attributed to a net doping reduction. Dielectric constant (ε') shows usual step-like transitions with corresponding relaxation peaks in dielectric loss. These peaks shift towards lower temperature as frequency decrease. Temperature dependant ac conductivity followed an Arrhenius relation with activation energy of 153 meV in the 200-290 K temperature range witch correspond to As vacancy. The results indicate that γ-rays irradiation improves the dielectric and electrical properties of the diode due to the defect annealing effect.

One-wire thermocouple

NASA Technical Reports Server (NTRS)

Goodrich, W. D.; Staimach, C. J.

1977-01-01

Nickel alloy/constantan device accurately measures surface temperature at precise locations. Device is moderate in cost and simplifies fabrication of highly-instrumented seamless-surface heat-transfer models. Device also applies to metal surfaces if constantan wire has insulative coat.

Design principles for radiation-resistant solid solutions

NASA Astrophysics Data System (ADS)

Schuler, Thomas; Trinkle, Dallas R.; Bellon, Pascal; Averback, Robert

2017-05-01

We develop a multiscale approach to quantify the increase in the recombined fraction of point defects under irradiation resulting from dilute solute additions to a solid solution. This methodology provides design principles for radiation-resistant materials. Using an existing database of solute diffusivities, we identify Sb as one of the most efficient solutes for this purpose in a Cu matrix. We perform density-functional-theory calculations to obtain binding and migration energies of Sb atoms, vacancies, and self-interstitial atoms in various configurations. The computed data informs the self-consistent mean-field formalism to calculate transport coefficients, allowing us to make quantitative predictions of the recombined fraction of point defects as a function of temperature and irradiation rate using homogeneous rate equations. We identify two different mechanisms according to which solutes lead to an increase in the recombined fraction of point defects; at low temperature, solutes slow down vacancies (kinetic effect), while at high temperature, solutes stabilize vacancies in the solid solution (thermodynamic effect). Extension to other metallic matrices and solutes are discussed.

COMSOL Multiphysics Model for HLW Canister Filling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesterson, M. R.

2016-04-11

The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. Wastes containing high concentrations of Al 2O 3 and Na 2O can contribute to nepheline (generally NaAlSiO 4) crystallization, which can sharply reduce the chemical durability of high level waste (HLW) glass. Nepheline crystallization canmore » occur during slow cooling of the glass within the stainless steel canister. The purpose of this work was to develop a model that can be used to predict temperatures of the glass in a WTP HLW canister during filling and cooling. The intent of the model is to support scoping work in the laboratory. It is not intended to provide precise predictions of temperature profiles, but rather to provide a simplified representation of glass cooling profiles within a full scale, WTP HLW canister under various glass pouring rates. These data will be used to support laboratory studies for an improved understanding of the mechanisms of nepheline crystallization. The model was created using COMSOL Multiphysics, a commercially available software. The model results were compared to available experimental data, TRR-PLT-080, and were found to yield sufficient results for the scoping nature of the study. The simulated temperatures were within 60 ºC for the centerline, 0.0762m (3 inch) from centerline, and 0.2286m (9 inch) from centerline thermocouples once the thermocouples were covered with glass. The temperature difference between the experimental and simulated values reduced to 40 ºC, 4 hours after the thermocouple was covered, and down to 20 ºC, 6 hours after the thermocouple was covered. This level of precision is considered acceptable for the scoping nature of the model and the subsequent laboratory glass studies Using the model, two additional glass pouring cycles were conducted. Representative thermocouple data were plotted to show the variations between the two cycles. This provides preliminary data that will be used in laboratory experiments to determine the potential for controlling nepheline crystallization in glass by varying the glass pouring conditions.« less

Simple method for measuring vibration amplitude of high power airborne ultrasonic transducer: using thermo-couple.

PubMed

Saffar, Saber; Abdullah, Amir

2014-03-01

Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of infrared thermometer with thermocouple for monitoring skin temperature.

PubMed

Matsukawa, T; Ozaki, M; Nishiyama, T; Imamura, M; Kumazawa, T

2000-02-01

To test the hypothesis that the infrared thermometer (Genius) is comparably useful with thermocouples that are routinely used for skin temperature monitoring. Prospective, controlled, not blinded study. Operating room of a university hospital. Ten healthy male volunteers. Volunteers were minimally clothed and were initially warmed by a forced air warmer until they became vasodilated at the finger and the foot for approximately 30 mins. Subsequently, they were kept in the room with no blanket. Skin temperatures were measured continuously with the Mon-a-Therm thermocouple and were also measured with the Genius thermometer just before and after the warming and subsequently every 10 mins for 70 mins. Forearm and finger-tip skin temperatures and skin-surface temperature gradients (from arm to finger and from calf to toe) measured by the Genius thermometer were compared with those measured by the Mon-a-Therm thermocouple using linear regression and Bland and Altman statistics. Forearm temperature and finger-tip temperature ranged from approximately 31 degrees to approximately 36.5 degrees C (87.8-97.7 degrees F) and approximately 22.5 degrees to approximately 36 degrees C (72.5-96.8 degrees F), respectively. Gradients (from arm to finger and from calf to toe) ranged from approximately -3 degrees to approximately 10 degrees C (26.6-50.0 degrees F) and approximately -3 degrees to approximately 11 degrees C (26.6-51.8 degrees F), respectively. Correlations between the temperatures measured by the Genius thermometer and those by the Mon-a-Therm thermocouple were similar and reliable. The correlation coefficients were as follows: 0.78 at forearm, 0.97 at finger-tip, and 0.97 at skin-surface temperature gradients. The infrared thermometer with a special probe is useful to measure the change of skin-surface temperatures and to evaluate the severity of shock in patients.

Effect of proton irradiation dose on InAlN/GaN metal-oxide semiconductor high electron mobility transistors with Al 2O 3 gate oxide

DOE PAGES

Ahn, Shihyun; Kim, Byung -Jae; Lin, Yi -Hsuan; ...

2016-07-26

The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al 2O 3 as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1×10 13 to 1×10 15cm –2 at a fixed energy of 5MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metalmore » contacts, with increases of specific contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current–voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 10 13 cm –2 V –1 for the reference MOSHEMTs to 6.7 × 10 13 cm –2 V –1 for devices irradiated with the highest dose. In conclusion, the carrier removal rate was 1287 ± 64 cm –1, higher than the authors previously observed in AlGaN/GaN MOSHEMTs for the same proton energy and consistent with the lower average bond energy of the InAlN.« less

A Multiple-range Self-balancing Thermocouple Potentiometer

NASA Technical Reports Server (NTRS)

Warshawsky, I; Estrin, M

1951-01-01

A multiple-range potentiometer circuit is described that provides automatic measurement of temperatures or temperature differences with any one of several thermocouple-material pairs. Techniques of automatic reference junction compensation, span adjustment, and zero suppression are described that permit rapid selection of range and wire material, without the necessity for restandardization, by setting of two external tap switches.

Thermocouple assembly

DOEpatents

Thermos, Anthony Constantine; Rahal, Fadi Elias

2002-01-01

A thermocouple assembly includes a thermocouple; a plurality of lead wires extending from the thermocouple; an insulating jacket extending along and enclosing the plurality of leads; and at least one internally sealed area within the insulating jacket to prevent fluid leakage along and within the insulating jacket. The invention also provides a method of preventing leakage of a fluid along and through an insulating jacket of a thermocouple including the steps of a) attaching a plurality of lead wires to a thermocouple; b) adding a heat sensitive pseudo-wire to extend along the plurality of lead wires; c) enclosing the lead wires and pseudo-wire inside an insulating jacket; d) locally heating axially spaced portions of the insulating jacket to a temperature which melts the pseudo-wire and fuses it with an interior surface of the jacket.

Memristive switching induced by 100 MeV Ag7+ ion irradiation in Ag/La0.7Sr0.3MnO3/Ag planar structures

NASA Astrophysics Data System (ADS)

Bhavsar, K. H.; Joshi, U. S.; Mistry, B. V.; Khan, S. A.; Avasthi, D. K.

2011-09-01

Resistive random access memory is one of the candidate technologies for the promising next generation non-volatile memories with fast switching speed, low power consumption and non-destructive readout. The swift heavy ion (SHI)-induced resistive switching behavior of Ag/La0.7Sr0.3MnO3/Ag planar structures, grown on SiO2 substrates by the chemical solution deposition technique, has been investigated. Five identical samples were irradiated by 100 MeV Ag7+ ions with fluence values ranging from 1×1011 to 5×1013 ions/cm2 at the Materials Science beamline of the IUAC, New Delhi. Upon irradiation, systematic amorphization and grain elongation was observed in the grazing incidence X-ray diffraction and atomic force microscopy, respectively. Four-terminal I-V curves indicate typical non-ohmic behavior of pristine Ag/La0.7Sr0.3MnO3/Ag planar geometry at room temperature for several voltage-sweeping cycles. On the other hand, well-defined hysteresis loops with sharp on-off transition in the I-V curves were observed for the sample irradiated with 100 MeV Ag7+ ions at 1×1012 ions/cm2, indicating that the sample possesses low resistance state and high resistance state. A symmetrical resistance ratio (R high/R low) of ∼ 330% at-1.7 V has been achieved. The resistance switching is bipolar and may be attributed to SHI-induced defects in the device. Such defect-induced resistive switching has recently been proposed theoretically, and our results are direct evidence of the phenomenon.

Effect of high fluence neutron irradiation on transport properties of thermoelectrics

NASA Astrophysics Data System (ADS)

Wang, H.; Leonard, K. J.

2017-07-01

Thermoelectric materials were subjected to high fluence neutron irradiation in order to understand the effect of radiation damage on transport properties. This study is relevant to the NASA Radioisotope Thermoelectric Generator (RTG) program in which thermoelectric elements are exposed to radiation over a long period of time in space missions. Selected n-type and p-type bismuth telluride materials were irradiated at the High Flux Isotope Reactor with a neutron fluence of 1.3 × 1018 n/cm2 (E > 0.1 MeV). The increase in the Seebeck coefficient in the n-type material was partially off-set by an increase in electrical resistivity, making the power factor higher at lower temperatures. For the p-type materials, although the Seebeck coefficient was not affected by irradiation, electrical resistivity decreased slightly. The figure of merit, zT, showed a clear drop in the 300-400 K range for the p-type material and an increase for the n-type material. Considering that the p-type and n-type materials are connected in series in a module, the overall irradiation damages at the device level were limited. These results, at neutron fluences exceeding a typical space mission, are significant to ensure that the radiation damage to thermoelectrics does not affect the performance of RTGs.

An Accurate Temperature Correction Model for Thermocouple Hygrometers 1

PubMed Central

Savage, Michael J.; Cass, Alfred; de Jager, James M.

1982-01-01

Numerous water relation studies have used thermocouple hygrometers routinely. However, the accurate temperature correction of hygrometer calibration curve slopes seems to have been largely neglected in both psychrometric and dewpoint techniques. In the case of thermocouple psychrometers, two temperature correction models are proposed, each based on measurement of the thermojunction radius and calculation of the theoretical voltage sensitivity to changes in water potential. The first model relies on calibration at a single temperature and the second at two temperatures. Both these models were more accurate than the temperature correction models currently in use for four psychrometers calibrated over a range of temperatures (15-38°C). The model based on calibration at two temperatures is superior to that based on only one calibration. The model proposed for dewpoint hygrometers is similar to that for psychrometers. It is based on the theoretical voltage sensitivity to changes in water potential. Comparison with empirical data from three dewpoint hygrometers calibrated at four different temperatures indicates that these instruments need only be calibrated at, e.g. 25°C, if the calibration slopes are corrected for temperature. PMID:16662241

Design and Construction of Experiment for Direct Electron Irradiation of Uranyl Sulfate Solution: Bubble Formation and Thermal Hydraulics Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chemerisov, Sergey; Gromov, Roman; Makarashvili, Vakho

Argonne is assisting SHINE Medical Technologies in developing SHINE, a system for producing fission-product 99Mo using a D/T-accelerator to produce fission in a non-critical target solution of aqueous uranyl sulfate. We have developed an experimental setup for studying thermal-hydraulics and bubble formation in the uranyl sulfate solution to simulate conditions expected in the SHINE target solution during irradiation. A direct electron beam from the linac accelerator will be used to irradiate a 20 L solution (sector of the solution vessel). Because the solution will undergo radiolytic decomposition, we will be able to study bubble formation and dynamics and effects ofmore » convection and temperature on bubble behavior. These experiments will serve as a verification/ validation tool for the thermal-hydraulic model. Utilization of the direct electron beam for irradiation allows homogeneous heating of a large solution volume and simplifies observation of the bubble dynamics simultaneously with thermal-hydraulic data collection, which will complement data collected during operation of the miniSHINE experiment. Irradiation will be conducted using a 30-40 MeV electron beam from the high-power linac accelerator. The total electron-beam power will be 20 kW, which will yield a power density on the order of 1 kW/L. The solution volume will be cooled on the front and back surfaces and central tube to mimic the geometry of the proposed SHINE solution vessel. Also, multiple thermocouples will be inserted into the solution vessel to map thermal profiles. The experimental design is now complete, and installation and testing are in progress.« less

Thermocouple Probe Orientation Affects Prescribed Fire Behavior Estimation.

PubMed

Coates, T Adam; Chow, Alex T; Hagan, Donald L; Waldrop, Thomas A; Wang, G Geoff; Bridges, William C; Rogers, Mary-Frances; Dozier, James H

2018-01-01

Understanding the relationship between fire intensity and fuel mass is essential information for scientists and forest managers seeking to manage forests using prescribed fires. Peak burning temperature, duration of heating, and area under the temperature profile are fire behavior metrics obtained from thermocouple-datalogger assemblies used to characterize prescribed burns. Despite their recurrent usage in prescribed burn studies, there is no simple protocol established to guide the orientation of thermocouple installation. Our results from dormant and growing season burns in coastal longleaf pine ( Mill.) forests in South Carolina suggest that thermocouples located horizontally at the litter-soil interface record significantly higher estimates of peak burning temperature, duration of heating, and area under the temperature profile than thermocouples extending 28 cm vertically above the litter-soil interface ( < 0.01). Surprisingly, vertical and horizontal estimates of these measures did not show strong correlation with one another ( ≤ 0.14). The horizontal duration of heating values were greater in growing season burns than in dormant season burns ( < 0.01), but the vertical values did not indicate this difference ( = 0.52). Field measures of fuel mass and depth before and after fire showed promise as significant predictive variables ( ≤ 0.05) for the fire behavior metrics. However, all correlation coefficients were less than or equal to = 0.41. Given these findings, we encourage scientists, researchers, and managers to carefully consider thermocouple orientation when investigating fire behavior metrics, as orientation may affect estimates of fire intensity and the distinction of fire treatment effects, particularly in forests with litter-dominated surface fuels. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Advantages of a Vertical High-Resolution Distributed-Temperature-Sensing System Used to Evaluate the Thermal Behavior of Green Roofs

NASA Astrophysics Data System (ADS)

Hausner, M. B.; Suarez, F. I.; Cousiño, J. A.; Victorero, F.; Bonilla, C. A.; Gironas, J. A.; Vera, S.; Bustamante, W.; Rojas, V.; Leiva, E.; Pasten, P.

2015-12-01

Technological innovations used for sustainable urban development, green roofs offer a range of benefits, including reduced heat island effect, rooftop runoff, roof surface temperatures, energy consumption, and noise levels inside buildings, as well as increased urban biodiversity. Green roofs feature layered construction, with the most important layers being the vegetation and the substrate layers located above the traditional roof. These layers provide both insulation and warm season cooling by latent heat flux, reducing the thermal load to the building. To understand and improve the processes driving this thermal energy reduction, it is important to observe the thermal dynamics of a green roof at the appropriate spatial and temporal scales. Traditionally, to observe the thermal behavior of green roofs, a series of thermocouples have been installed at discrete depths within the layers of the roof. Here, we present a vertical high-resolution distributed-temperature-sensing (DTS) system installed in different green roof modules of the Laboratory of Vegetated Infrastructure for Buildings (LIVE -its acronym in Spanish) of the Pontifical Catholic University of Chile. This DTS system allows near-continuous measurement of the thermal profile at spatial and temporal resolutions of approximately 1 cm and 30 s, respectively. In this investigation, the temperature observations from the DTS system are compared with the measurements of a series of thermocouples installed in the green roofs. This comparison makes it possible to assess the value of thermal observations at better spatial and temporal resolutions. We show that the errors associated with lower resolution observations (i.e., from the thermocouples) are propagated in the calculations of the heat fluxes through the different layers of the green roof. Our results highlight the value of having a vertical high-resolution DTS system to observe the thermal dynamics in green roofs.

Advances in Thin Film Sensor Technologies for Engine Applications

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Martin, Lisa C.; Will, Herbert A.

1997-01-01

Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.

The nano-particle dispersion strengthening of V-4Cr-4Ti alloys for high temperature application in fusion reactors

NASA Astrophysics Data System (ADS)

Zheng, Pengfei; Chen, Jiming; Xu, Zengyu; Duan, Xuru

2013-10-01

V-4Cr-4Ti was identified as an attractive structural material for Li blanket in fusion reactors. However, both high temperature and irradiation induced degradation are great challenges for this material. It was thought that the nano-particles with high thermal stability can efficiently strengthen the alloy at elevated temperatures, and accommodate the irradiation induced defects at the boundaries. This study is a starting work aiming at improving the creep resistance and reducing the irradiation induced degradation for V-4Cr-4Ti alloy. Currently, we focus on the preparation of some comparative nano-particle dispersion strengthened V-4Cr-4Ti alloys. A mechanical alloying (MA) route is used to fabricate yttrium and carbides added V-4Cr-4Ti alloys. Nano-scale yttria, carbides and other possible particles have a combined dispersion-strengthening effect on the matrices of these MA-fabricated V-4Cr-4Ti alloys. High-temperature annealing is carried out to stabilize the optimized nano-particles. Mechanical properties are tested. Microstructures of the MA-fabricated V-4Cr-4Ti alloys with yttrium and carbide additions are characterized. Based on these results, the thermal stability of different nano-particle agents are classified. ITER related China domestic project 2011GB108007.

Temperature Dependent Resistivity and Hall Effect in Proton Irradiated CdS Thin Films

NASA Astrophysics Data System (ADS)

Guster, B.; Ghenescu, V.; Ion, L.; Radu, A.; Porumb, O.; Antohe, S.

2011-10-01

Cadmium sulphide finds extensive applications in a variety of optoelectronic devices. In particular, CdS thin films are suitable for use as windows in heterojunction solar cells that employ CdTe, Cu2S or CuInSe2 as an absorber. Such thin film based solar cells are well suited for use in space technology. For that specific application, it is important to know how ionizing radiations alter their performance. We have investigated the effects of irradiation with high energy protons (3 MeV), at 1014 fluency, on electrical properties of polycrystalline CdS thin layers. The samples were prepared by thermal vacuum deposition from single source onto optical glass substrate. Temperature dependent electrical resistivity and Hall effect, before and after irradiation, were recorded from 300 K down to 4 K. The experimental results can be explained in the frame of a two-band model. Above 100 K electrical properties are controlled by a defect level of donor type, with an ionization energy of about 0.060 eV. The possible origin of this defect is discussed.

Assessment of Titanium Aluminide Alloys for High-Temperature Nuclear Structural Applications

NASA Astrophysics Data System (ADS)

Zhu, Hanliang; Wei, Tao; Carr, David; Harrison, Robert; Edwards, Lyndon; Hoffelner, Wolfgang; Seo, Dongyi; Maruyama, Kouichi

2012-12-01

Titanium aluminide (TiAl) alloys exhibit high specific strength, low density, good oxidation, corrosion, and creep resistance at elevated temperatures, making them good candidate materials for aerospace and automotive applications. TiAl alloys also show excellent radiation resistance and low neutron activation, and they can be developed to have various microstructures, allowing different combinations of properties for various extreme environments. Hence, TiAl alloys may be used in advanced nuclear systems as high-temperature structural materials. Moreover, TiAl alloys are good materials to be used for fundamental studies on microstructural effects on irradiation behavior of advanced nuclear structural materials. This article reviews the microstructure, creep, radiation, and oxidation properties of TiAl alloys in comparison with other nuclear structural materials to assess the potential of TiAl alloys as candidate structural materials for future nuclear applications.

Corneal surface temperature change as the mode of stimulation of the non-contact corneal aesthesiometer.

PubMed

Murphy, P J; Morgan, P B; Patel, S; Marshall, J

1999-05-01

The non-contact corneal aesthesiometer (NCCA) assesses corneal sensitivity by using a controlled pulse of air, directed at the corneal surface. The purpose of this paper was to investigate whether corneal surface temperature change was a component in the mode of stimulation. Thermocouple experiment: A simple model corneal surface was developed that was composed of a moistened circle of filter paper placed on a thermocouple and mounted on a glass slide. The temperature change produced by different stimulus pressures was measured for five different ambient temperatures. Thermal camera experiment: Using a thermal camera, the corneal surface temperature change was measured in nine young, healthy subjects after exposure to different stimulus air pulses. Pulse duration was set at 0.9 s but was varied in pressure from 0.5 to 3.5 millibars. Thermocouple experiment: An immediate drop in temperature was detected by the thermocouple as soon as the air flow was incident on the filter paper. A greater temperature change was produced by increasing the pressure of the incident air flow. A relationship was found and a calibration curve plotted. Thermal camera experiment: For each subject, a drop in surface temperature was detected at each stimulus pressure. Furthermore, as the stimulus pressure increased, the induced reduction in temperature also increased. A relationship was found and a calibration curve plotted. The NCCA air-pulse stimulus was capable of producing a localized temperature change on the corneal surface. The principal mode of corneal nerve stimulation, by the NCCA air pulse, was the rate of temperature change of the corneal surface.

Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

NASA Astrophysics Data System (ADS)

Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

2010-11-01

A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

Temperature variation during apicectomy with Er:YAG laser.

PubMed

Bodrumlu, Emre; Keskiner, Ilker; Sumer, Mahmut; Sumer, A Pinar; Telcıoglu, N Tuba

2012-08-01

The purpose of this in vitro study was to evaluate the generated temperature of the Er:YAG laser, with three different pulse durations for apicectomy, compared with tungsten bur and surgical saw. Apicectomy is an endodontic surgery performed to remove the root apex and curette adjacent periapical tissue because of lesions of the apical area that are not healing properly. Sixty single-rooted extracted human teeth were resected by three cutting methods: tungsten bur, surgical saw, and Er:YAG laser irradiation with three different pulse durations; pulse duration 50 μs, pulse duration 100 μs, and pulse duration 300 μs. Teflon-insulated, type K thermocouples were used to measure temperature changes during the apicectomy process. Data were analyzed using the general linear models procedure of the SPSS statistical software program. Although there was no statistically significant difference for the mean values of temperature changes at 1 mm away to the cutting site of teeth, there was statistically significant difference among groups for the mean values of temperature changes at 3 mm away to the cutting site of teeth. Additionally, there was statistically significant difference among groups for the total time required for apicectomy. The laser irradiation with pulse duration 50 μs appears to have the lowest temperature rise and the shortest time required for apicectomy of the three pulse durations. However, Er:YAG laser for apicectomy in all pulse durations could be used safely for resection in endodontics in the presence of sufficient water.

THERMAL COUPLE FOR MEASURING TEMPERATURE IN A REACTOR

DOEpatents

Kanne, W.

1959-11-24

A thermocouple device for measuring the temperature of a flowing fluid in a conduit within which is positioned a metallic rod is presented. A thermocouple junction is secured to the rod centrally, and thermal insulating support disks having a diameter greater than the rod are secured to the end portions of the rod and adapted to fit transversely in the conduit.

Measurement of high-dynamic temperature field using high-speed quadriwave lateral shearing interferometer

NASA Astrophysics Data System (ADS)

Cui, Bo-chuan; Wang, Jian-li; Yao, Kai-nan; Chen, Tao

2018-03-01

An approach to measure a high-dynamic two-dimensional (2D) temperature field using a high-speed quadriwave lateral shearing interferometer (QWLSI) is proposed. The detailed theoretical derivation to express the wavefront reconstruct principle of the proposed method is presented. The comparison experiment with thermocouples shows that the temperature field measurement using QWLSI has a precision of ±0.5 °C. An experiment for measuring the highdynamic temperature field generated by an electrical heater is carried out. A 200 frame rate temperature field video with 512 × 512 resolution is obtained finally. Experimental results show that the temperature field measurement system using a QWLSI has the advantage of high sensitivity and high resolution.

Outdoor surface temperature measurement: ground truth or lie?

NASA Astrophysics Data System (ADS)

Skauli, Torbjorn

2004-08-01

Contact surface temperature measurement in the field is essential in trials of thermal imaging systems and camouflage, as well as for scene modeling studies. The accuracy of such measurements is challenged by environmental factors such as sun and wind, which induce temperature gradients around a surface sensor and lead to incorrect temperature readings. In this work, a simple method is used to test temperature sensors under conditions representative of a surface whose temperature is determined by heat exchange with the environment. The tested sensors are different types of thermocouples and platinum thermistors typically used in field trials, as well as digital temperature sensors. The results illustrate that the actual measurement errors can be much larger than the specified accuracy of the sensors. The measurement error typically scales with the difference between surface temperature and ambient air temperature. Unless proper care is taken, systematic errors can easily reach 10% of this temperature difference, which is often unacceptable. Reasonably accurate readings are obtained using a miniature platinum thermistor. Thermocouples can perform well on bare metal surfaces if the connection to the surface is highly conductive. It is pointed out that digital temperature sensors have many advantages for field trials use.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

PubMed

El Gamal, Ahmed; Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-03-31

The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

Metrological Software Test for Simulating the Method of Determining the Thermocouple Error in Situ During Operation

NASA Astrophysics Data System (ADS)

Chen, Jingliang; Su, Jun; Kochan, Orest; Levkiv, Mariana

2018-04-01

The simplified metrological software test (MST) for modeling the method of determining the thermocouple (TC) error in situ during operation is considered in the paper. The interaction between the proposed MST and a temperature measuring system is also reflected in order to study the error of determining the TC error in situ during operation. The modelling studies of the random error influence of the temperature measuring system, as well as interference magnitude (both the common and normal mode noises) on the error of determining the TC error in situ during operation using the proposed MST, have been carried out. The noise and interference of the order of 5-6 μV cause the error of about 0.2-0.3°C. It is shown that high noise immunity is essential for accurate temperature measurements using TCs.

Electrical, thermal and magnetic studies on 7.5 MeV electron beam irradiated PrCoO3 polycrystalline samples

NASA Astrophysics Data System (ADS)

Christopher, Benedict; Rao, Ashok; Deka, Utpal; Prasad K, Shyam; Okram, G. S.; Sanjeev, Ganesh; Chandra Petwal, Vikash; Verma, Vijay Pal; Dwivedi, Jishnu

2018-07-01

The study of electronic and magnetic properties of electron beam (EB) irradiated PrCoO3 manganites is presented in this communication. The diffraction data confirms that pristine as well as electron beam irradiated samples are single phased and they crystalize at orthorhombic distorted structure with Pbnm space group. The electrical resistivity of all the samples reveals semiconducting behavior. Small polaron hopping model is appropriately employed to investigate the semiconducting nature of the pristine and EB irradiated samples. The Seebeck coefficient (S) data of the pristine sample exhibits colossally high positive value (about 300 mV/K) and substantial decrease in S value is noticed in the irradiated samples. The high temperature analysis of thermopower data validates the small polaron hopping model. The magnetic measurements display possible existence of super-paramagnetic characteristics in the samples.

Isolation of Radiation-Resistant Bacteria from Mars Analog Antarctic Dry Valleys by Preselection, and the Correlation between Radiation and Desiccation Resistance

PubMed Central

Wright, Gary; Ward, John M.; Dartnell, Lewis R.

2015-01-01

Abstract Extreme radiation–resistant microorganisms can survive doses of ionizing radiation far greater than are present in the natural environment. Radiation resistance is believed to be an incidental adaptation to desiccation resistance, as both hazards cause similar cellular damage. Desert soils are, therefore, promising targets to prospect for new radiation-resistant strains. This is the first study to isolate radiation-resistant microbes by using gamma-ray exposure preselection from the extreme cold desert of the Antarctic Dry Valleys (a martian surface analogue). Halomonads, identified by 16S rRNA gene sequencing, were the most numerous survivors of the highest irradiation exposures. They were studied here for the first time for both their desiccation and irradiation survival characteristics. In addition, the association between desiccation and radiation resistance has not been investigated quantitatively before for a broad diversity of microorganisms. Thus, a meta-analysis of scientific literature was conducted to gather a larger data set. A strong correlation was found between desiccation and radiation resistance, indicating that an increase in the desiccation resistance of 5 days corresponds to an increase in the room-temperature irradiation survival of 1 kGy. Irradiation at −79°C (representative of average martian surface temperatures) increases the microbial radiation resistance 9-fold. Consequently, the survival of the cold-, desiccation-, and radiation-resistant organisms isolated here has implications for the potential habitability of dormant or cryopreserved life on Mars. Key Words: Extremophiles—Halomonas sp.—Antarctica—Mars—Ionizing radiation—Cosmic rays. Astrobiology 15, 1076–1090. PMID:26684506

Fabrication and Characterization of CMOS-MEMS Thermoelectric Micro Generators

PubMed Central

Kao, Pin-Hsu; Shih, Po-Jen; Dai, Ching-Liang; Liu, Mao-Chen

2010-01-01

This work presents a thermoelectric micro generator fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-CMOS process. The micro generator is composed of 24 thermocouples in series. Each thermocouple is constructed by p-type and n-type polysilicon strips. The output power of the generator depends on the temperature difference between the hot and cold parts in the thermocouples. In order to prevent heat-receiving in the cold part in the thermocouples, the cold part is covered with a silicon dioxide layer with low thermal conductivity to insulate the heat source. The hot part of the thermocouples is suspended and connected to an aluminum plate, to increases the heat-receiving area in the hot part. The generator requires a post-CMOS process to release the suspended structures. The post-CMOS process uses an anisotropic dry etching to remove the oxide sacrificial layer and an isotropic dry etching to etch the silicon substrate. Experimental results show that the micro generator has an output voltage of 67 μV at the temperature difference of 1 K. PMID:22205869

A computer-controlled apparatus for Seebeck inhomogeneity testing of sheathed thermocouples

NASA Technical Reports Server (NTRS)

Burkett, Cecil G., Jr.; Bauserman, Willard A., Jr.

1993-01-01

Mineral-insulated metal-sheathed (MIMS) thermocouple assemblies are used throughout industry and research facilities as a method of temperature measurement where requirements for either harsh environmental conditions exist, or where rigidity of the measurement probe is required. Seebeck inhomogeneity is the abnormal variation of the Seebeck coefficient from point to point in a material. It is not disclosed in conventional calibration. A standardized method of measuring thermoelectric inhomogeneity along the thermocouple probe length is not available. Therefore, calibration for sheathed probes normally does not include testing of probe inhomogeneity. The measurement accuracy would be severely impacted if significant inhomogeneity and a temperature gradient were present in the same region of the probe. A computer-controlled system for determining inhomogeneities was designed, fabricated, and tested. This system provides an accurate method for the identification of the location of inhomogeneity along the length of a sheathed thermocouple and for the quantification of the inhomogeneity. This paper will discuss the apparatus and procedure used to perform these tests and will present data showing tests performed on sheathed thermocouple probes.

The resistance of the lichen Circinaria gyrosa (nom. provis.) towards simulated Mars conditions—a model test for the survival capacity of an eukaryotic extremophile

NASA Astrophysics Data System (ADS)

Sánchez, F. J.; Mateo-Martí, E.; Raggio, J.; Meeßen, J.; Martínez-Frías, J.; Sancho, L. G.^a..; Ott, S.; de la Torre, R.

2012-11-01

The "Planetary Atmospheres and Surfaces Chamber" (PASC, at Centro de Astrobiología, INTA, Madrid) is able to simulate the atmosphere and surface temperature of most of the solar system planets. PASC is especially appropriate to study irradiation induced changes of geological, chemical, and biological samples under a wide range of controlled atmospheric and temperature conditions. Therefore, PASC is a valid method to test the resistance potential of extremophile organisms under diverse harsh conditions and thus assess the habitability of extraterrestrial environments. In the present study, we have investigated the resistance of a symbiotic organism under simulated Mars conditions, exemplified with the lichen Circinaria gyrosa - an extremophilic eukaryote. After 120 hours of exposure to simulated but representative Mars atmosphere, temperature, pressure and UV conditions; an unaltered photosynthetic performance demonstrated high resistance of the lichen photobiont.

Role of temperature in the radiation stability of yttria stabilized zirconia under swift heavy ion irradiation: A study from the perspective of nuclear reactor applications

NASA Astrophysics Data System (ADS)

Kalita, Parswajit; Ghosh, Santanu; Sattonnay, Gaël; Singh, Udai B.; Grover, Vinita; Shukla, Rakesh; Amirthapandian, S.; Meena, Ramcharan; Tyagi, A. K.; Avasthi, Devesh K.

2017-07-01

The search for materials that can withstand the harsh radiation environments of the nuclear industry has become an urgent challenge in the face of ever-increasing demands for nuclear energy. To this end, polycrystalline yttria stabilized zirconia (YSZ) pellets were irradiated with 80 MeV Ag6+ ions to investigate their radiation tolerance against fission fragments. To better simulate a nuclear reactor environment, the irradiations were carried out at the typical nuclear reactor temperature (850 °C). For comparison, irradiations were also performed at room temperature. Grazing incidence X-ray diffraction and Raman spectroscopy measurements reveal degradation in crystallinity for the room temperature irradiated samples. No bulk structural amorphization was however observed, whereas defect clusters were formed as indicated by transmission electron microscopy and supported by thermal spike simulation results. A significant reduction of the irradiation induced defects/damage, i.e., improvement in the radiation tolerance, was seen under irradiation at 850 °C. This is attributed to the fact that the rapid thermal quenching of the localized hot molten zones (arising from spike in the lattice temperature upon irradiation) is confined to 850 °C (i.e., attributed to the resistance inflicted on the rapid thermal quenching of the localized hot molten zones by the high temperature of the environment) thereby resulting in the reduction of the defects/damage produced. Our results present strong evidence for the applicability of YSZ as an inert matrix fuel in nuclear reactors, where competitive effects of radiation damage and dynamic thermal healing mechanisms may lead to a strong reduction in the damage production and thus sustain its physical integrity.

Magnetic tunnel junction thermocouple for thermoelectric power harvesting

NASA Astrophysics Data System (ADS)

Böhnert, T.; Paz, E.; Ferreira, R.; Freitas, P. P.

2018-05-01

The thermoelectric power generated in magnetic tunnel junctions (MTJs) is determined as a function of the tunnel barrier thickness for a matched electric circuit. This study suggests that lower resistance area product and higher tunnel magnetoresistance will maximize the thermoelectric power output of the MTJ structures. Further, the thermoelectric behavior of a series of two MTJs, a MTJ thermocouple, is investigated as a function of its magnetic configurations. In an alternating magnetic configurations the thermovoltages cancel each other, while the magnetic contribution remains. A large array of MTJ thermocouples could amplify the magnetic thermovoltage signal significantly.

Non-uniform temperature and species concentration measurements in a laminar flame using multi-band infrared absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ma, Liu Hao; Lau, Lok Yin; Ren, Wei

2017-03-01

We report in situ measurements of non-uniform temperature, H2O and CO2 concentration distributions in a premixed methane-air laminar flame using tunable diode laser absorption spectroscopy (TDLAS). A mid-infrared, continuous-wave, room-temperature interband cascade laser (ICL) at 4183 nm was used for the sensitive detection of CO2 at high temperature.The H2O absorption lines were exploited by one distributed feedback (DFB) diode laser at 1343 nm and one ICL at 2482 nm to achieve multi-band absorption measurements with high species concentration sensitivity, high temperature sensitivity, and immunity to variations in ambient conditions. A novel profile-fitting function was proposed to characterize the non-uniform temperature and species concentrations along the line-of-sight in the flame by detecting six absorption lines of CO2 and H2O simultaneously. The flame temperature distribution was measured at different heights above the burner (5-20 mm), and compared with the thermocouple measurement with heat-transfer correction. Our TDLAS measured temperature of the central flame was in excellent agreement (<1.5% difference) with the thermocouple data.The TDLAS results were also compared with the CFD simulations using a detailed chemical kinetics mechanism (GRI 3.0) and considering the heat loss to the surroundings.The current CFD simulation overpredicted the flame temperature in the gradient region, but was in excellent agreement with the measured temperature and species concentration in the core of the flame.

Thin-film sensors for space propulsion technology: Fabrication and preparation for testing

NASA Technical Reports Server (NTRS)

Kim, Walter S.; Hepp, Aloysius F.

1989-01-01

The goal of this work is to develop and test thin-film thermocouples for Space Shuttle Main Engine (SSME) components. Thin-film thermocouples have been developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the SSME, especially severe thermal shock from cryogenic fuel to combustion temperatures. Initial results using coupons of MAR M-246 (+Hf) and PWA 1480 have been followed by fabrication of thin-film thermocouples on SSME turbine blades. Current efforts are focused on preparing for testing in the Turbine Blade Tester at the NASA Marshall Space Flight Center (MSFC). Future work will include testing of thin-film thermocouples on SSME blades of single crystal PWA 1480 at MSFC.

ITS-90 Thermocouple Database

National Institute of Standards and Technology Data Gateway

SRD 60 NIST ITS-90 Thermocouple Database (Web, free access)   Web version of Standard Reference Database 60 and NIST Monograph 175. The database gives temperature -- electromotive force (emf) reference functions and tables for the letter-designated thermocouple types B, E, J, K, N, R, S and T. These reference functions have been adopted as standards by the American Society for Testing and Materials (ASTM) and the International Electrotechnical Commission (IEC).

The reliability of thermocouples in microwave ceramics processing.

PubMed

Aguilar, Juan; Valdez, Zarel; Ortiz, Ubaldo

2004-01-01

It is not rare to hear arguments against the use of thermocouples for taking temperatures in processes that are taking place under microwave fields. However, the simplicity of this device makes it attractive to consider its use. One question that arises when thermocouples are employed is whether the electric field perturbs the measurement, and if the thermocouple affects the processing. The process that was chosen for conducting this test was the synthesis of spinel (MgAl2O4) using microwaves as a power supply and hematite (Fe2O3) as an additive for both spinel formation promotion and susceptor. The alumina-based systems are very important to study because this is one of the most common ingredients in refractory materials. There are many discussions about the improvement of the process when microwaves are used, but a kinetic comparison cannot be performed if the temperature is unknown, and that is the reason for emphasizing the measurement techniques. The analysis of the obtained samples was carried out by X-ray diffraction of powders. The results of this work show that there is no difference between the products obtained when the thermocouple was inserted in the system, compared to processing without it; hence the thermocouple is appropriate for this application.

Cutting Zone Temperature Identification During Machining of Nickel Alloy Inconel 718

NASA Astrophysics Data System (ADS)

Czán, Andrej; Daniš, Igor; Holubják, Jozef; Zaušková, Lucia; Czánová, Tatiana; Mikloš, Matej; Martikáň, Pavol

2017-12-01

Quality of machined surface is affected by quality of cutting process. There are many parameters, which influence on the quality of the cutting process. The cutting temperature is one of most important parameters that influence the tool life and the quality of machined surfaces. Its identification and determination is key objective in specialized machining processes such as dry machining of hard-to-machine materials. It is well known that maximum temperature is obtained in the tool rake face at the vicinity of the cutting edge. A moderate level of cutting edge temperature and a low thermal shock reduce the tool wear phenomena, and a low temperature gradient in the machined sublayer reduces the risk of high tensile residual stresses. The thermocouple method was used to measure the temperature directly in the cutting zone. An original thermocouple was specially developed for measuring of temperature in the cutting zone, surface and subsurface layers of machined surface. This paper deals with identification of temperature and temperature gradient during dry peripheral milling of Inconel 718. The measurements were used to identification the temperature gradients and to reconstruct the thermal distribution in cutting zone with various cutting conditions.

Measurements of matric and water potentials in unsaturated tuff at Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thamir, F.; McBride, C.M.

1985-12-31

Two types of instruments were installed in a borehole in order to monitor matric and water potentials of various hydrogeologic units consisting of tuff. The borehole was drilled as part of a study to provide information to the US Department of Energy for their use in evaluating Yucca Mountain, Nevada, for a repository for high-level radioactive waste. Heat-dissipation probes were used to monitor matric potentials and thermocouple psychrometers were used to monitor water potentials. Two major concerns regarding the use of these instruments in deep boreholes are: (1) the effect of length of the lead wires, and (2) the inabilitymore » to recalibrate the instruments after installation. The length of the lead wire contributes to the source resistance and lead capacitance, which affects the signal settling time. Both instruments tested proved to be insensitive to lead-wire length, except when connected to smaller input-impedance data loggers. Thermocouple wires were more sensitive than heat-dissipation probe wires because of their greater resistance and quality of voltmeters used. Two thermocouple psychrometers were installed at every instrument station for backup and verification of data, because the instruments could not be recalibrated in situ. Multiple scanning rather than single-point scanning of the evaporation curve of a thermocouple psychrometer could give more reliable data, especially in differentiating between very wet and very dry environments. An isolated power supply needs to be used for each heat dissipation probe rather than a single power supply for a group of probes to avoid losing data from all probes when one probe malfunctions. This type of system is particularly desirable if the site is unattended by an operator for as long as a month. 20 refs., 13 figs., 2 tabs.« less

Correction for Thermal EMFs in Thermocouple Feedthroughs

NASA Technical Reports Server (NTRS)

Ziemke, Robert A.

2006-01-01

A straightforward measurement technique provides for correction of thermal-electromotive-force (thermal-EMF) errors introduced by temperature gradients along the pins of non-thermocouple-alloy hermetic feedthrough connectors for thermocouple extension wires that must pass through bulkheads. This technique is an alternative to the traditional technique in which the thermal-EMF errors are eliminated by use of custom-made multipin hermetic feedthrough connectors that contain pins made of the same alloys as those of the thermocouple extension wires. One disadvantage of the traditional technique is that it is expensive and time-consuming to fabricate multipin custom thermocouple connectors. In addition, the thermocouple-alloy pins in these connectors tend to corrode easily and/or tend to be less rugged compared to the non-thermocouple-alloy pins of ordinary connectors. As the number of thermocouples (and thus pins) is increased in a given setup, the magnitude of these disadvantages increases accordingly. The present technique is implemented by means of a little additional hardware and software, the cost of which is more than offset by the savings incurred through the use of ordinary instead of thermocouple connectors. The figure schematically depicts a typical measurement setup to which the technique is applied. The additional hardware includes an isothermal block (made of copper) instrumented with a reference thermocouple and a compensation thermocouple. The reference thermocouple is connected to an external data-acquisition system (DAS) through a two-pin thermocouple-alloy hermetic feedthrough connector, but this is the only such connector in the apparatus. The compensation thermocouple is connected to the DAS through two pins of the same ordinary multipin connector that connects the measurement thermocouples to the DAS.

Development of advanced high-temperature heat flux sensors

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Strange, R. R.

1982-01-01

Various configurations of high temperature, heat flux sensors were studied to determine their suitability for use in experimental combustor liners of advanced aircraft gas turbine engines. It was determined that embedded thermocouple sensors, laminated sensors, and Gardon gauge sensors, were the most viable candidates. Sensors of all three types were fabricated, calibrated, and endurance tested. All three types of sensors met the fabricability survivability, and accuracy requirements established for their application.

Testing of Candidate Rigid Heatshield Materials at LHMEL for the Entry, Descent, and Landing Technology Development Project

NASA Technical Reports Server (NTRS)

Sepka, Steven; Gasch, Matthew; Beck, Robin A.; White, Susan

2012-01-01

The material testing results described in this paper were part of a material development program of vendor-supplied, proposed heat shield materials. The goal of this program was to develop low density, rigid material systems with an appreciable weight savings over phenolic-impregnated carbon ablator (PICA) while improving material response performance. New technologies, such as PICA-like materials in honeycomb or materials with variable density through-the-thickness were tested. The material testing took place at the Wright-Patterson Air Force Base Laser Hardened Materials Laboratory (LHMEL) using a 10.6 micron CO2 laser operating with the test articles immersed in a nitrogen-gas environment at 1 atmosphere pressure. Test measurements included thermocouple readings of in-depth temperatures, pyrometer readings of surface temperatures, weight scale readings of mass loss, and sectioned-sample readings of char depth. Two laser exposures were applied. The first exposure was at an irradiance of 450 W/cm2 for 50 or 60 seconds to simulate an aerocapture maneuver. The second laser exposure was at an irradiance of 115 W/cm2 for 100 seconds to simulate a planetary entry. Results from Rounds 1 and 2 of these screening tests are summarized.

NIM gas controlled sodium heat pipe

NASA Astrophysics Data System (ADS)

Yan, X.; Zhang, J. T.; Merlone, A.; Duan, Y.; Wang, W.

2013-09-01

Gas controlled heat pipes (GCHPs) provide a uniform, stable and reproducible temperature zone to calibrate thermometers and thermocouples, and to realize defining fixed points using a calorimetric method. Therefore, to perform such investigations, a GCHP furnace using sodium as its working fluid was constructed at the National Institute of Metrology (NIM), China. Also, investigations into the thermal characteristics of the NIM gas controlled sodium heat pipe were carried out. The temperature stability over 5 hours was better than ±0.25 mK while controlling the pressure at 111250 Pa. The temperature uniformity within 14 cm from the bottom of the thermometer well was within 0.3 mK. While keeping the pressure stable at the same value, 17 temperature determinations were performed over 14 days, obtaining a temperature reproducibility of 1.27 mK. Additionally, the NIM gas controlled sodium heat pipe was compared with the sodium heat pipe produced by INRiM. The temperature in the INRiM sodium heat pipe operating at 111250 Pa was determined, obtaining a difference of 21 mK with respect to the NIM GCHP. This difference was attributed to sodium impurities, pressure controller capabilities and reproducibility, and instabilities of high temperature standard platinum resistance thermometers (HTSPRTs). Further investigations will be carried out on extending the pressure/temperature range and connecting both GCHPs to the same pressure line.