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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Enhanced Design of Radiation Tolerant High-Temperature Structural Health Monitoring Sensors

Acoustic emission sensors are vital in the nuclear industry for real-time structural health monitoring and early detection of material degradation. By capturing high-frequency stress waves emitted from defects like cracks, corrosion, or fatigue, acoustic emission sensors enable non-invasive monitoring of critical components such as reactor vessels, piping, and containment structures. This technology supports predictive maintenance, enhances safety, and ensures regulatory compliance by providing early warnings of potential failures. It is also instrumental in research, particularly in material testing reactors, where it is used to monitor the behavior of fuels and materials under irradiation, by allowing the detection of cracking or other acoustic signals in real time. This enables the evaluation of performance and accident behavior of advanced fuel concepts.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
NASA NTRS1984

High-temperature fiber optic pressure sensor

Attention is given to a program to develop fiber optic methods to measure diaphragm deflection. The end application is intended for pressure transducers capable of operating to 540 C. In this paper are reported the results of a laboratory study to characterize the performance of the fiber-optic microbend sensor. The data presented include sensitivity and spring constant. The advantages and limitations of the microbend sensor for static pressure measurement applications are described. A proposed design is presented for a 540 C pressure transducer using the fiber optic microbend sensor.

Berthold, J. W.↗
NASA NTRS2011

Improved Reliability of SiC Pressure Sensors for Long Term High Temperature Applications

We report advancement in the reliability of silicon carbide pressure sensors operating at 600 C for extended periods. The large temporal drifts in zero pressure offset voltage at 600 C observed previously were significantly suppressed to allow improved reliable operation. This improvement was the result of further enhancement of the electrical and mechanical integrity of the bondpad/contact metallization, and the introduction of studded bump bonding on the pad. The stud bump contact promoted strong adhesion between the Au bond pad and the Au die-attach. The changes in the zero offset voltage and bridge resistance over time at temperature were explained by the microstructure and phase changes within the contact metallization, that were analyzed with Auger electron spectroscopy (AES) and field emission scanning electron microscopy (FE-SEM).

Okojie, R. S.↗
DOE OSTI2020

Laser-assisted embedding of all-glass optical fiber sensors into bulk ceramics for high-temperature applications

We develop a laser-assisted sensor embedding process to embed all-glass optical fiber sensors into bulk ceramics for high-temperature applications. A specially designed two-step microchannel was fabricated on an Al 2 O 3 substrate for sensor embedment using a picosecond (ps) laser. An optical fiber Intrinsic Fabry-Perot Interferometer (IFPI) sensor was embedded at the bottom of the microchannel and covered by Al 2 O 3 slurry which was subsequently sintered by a CO 2 laser. The sensor spectrum was in-situ monitored during the laser sintering process to ensure the survival of the sensor and optimize the laser sintering parameters. By testing in furnace through high temperature, the embedded optical fiber shows improved stability after CO 2 laser sealing, resulting in the linear temperature response of the embedded optical fiber IFPI sensor. To improve the embedded IFPI sensor for thermal strain measurement, a dummy fiber was co-embedded with the sensing fiber to improve the mechanical bonding between the sensing fiber and the ceramic substrate so that the thermal strain of the ceramic substrate can apply on the sensing fiber. The response sensitivity, measurement repeatability and high-temperature long-term stability of the embedded optical fiber IFPI sensor were evaluated in this work.

47 OTHER INSTRUMENTATION↗
NASA NTRS1981

H2O frost point detection on Mars

The Viking Mars landers contain meteorological instrumentation to measure wind, temperature, and pressure but not atmospheric water content. The landings occurred during local summer, and it was observed that the nocturnal temperature decrease at sensor height (1.6 m) did not exhibit a uniform behavior at either site. It was expected that the rate of decrease would gradually slow, leveling off near sunrise. Instead, a leveling occurred several hours earlier. Temperature subsequently began a more rapid decrease which slowed by sunrise. This suggested that the temperature sensors may be detecting the frost point of water vapor. Analysis of alternative hypotheses demonstrates that none of these are viable candidates. The frost point interpretation is consistent with other lander and orbiter observations, with terrestrial experience, and with modeling of Mars' atmospheric behavior. It thus appears that the meteorology experiment can help provide a basis toward understanding the distribution and dynamics of Martian water vapor.

Ryan, J. A.↗
DOE OSTI2022

High-temperature superelasticity in NiTiPt and NiTiPd shape memory alloys

Alloying NiTi shape memory alloys with sufficient Pt and Pd at the expense of Ni has been shown to increase transformation temperatures well above those possible with the binary composition, enabling consideration of a new class of high-temperature mechanical sensors and actuators. To achieve shape memory behavior at temperatures greater than 200 °C, previous studies of NiTiPt and NiTiPd compositions have focused primarily on alloys with greater than 16 at.% Pt and 25 at.% Pd. While generally not the focus, none of these previous studies demonstrated superelastic behavior at high temperatures. In an effort to identify alloys that transform to austenite at approximately 200 °C and exhibit superelastic behavior with recoverable strains greater than 2%, a series of Ti-rich NiTiPt ternary alloys with 15.5–16.5 at.% Pt, and Ti-rich NiTiPd ternary alloys with 25–26 at.% Pd have been targeted. The polycrystalline alloys were processed via arc melting followed by homogenization heat treatment. Thermomechanical properties were measured using electro-discharge machined tension test coupons and a miniature load frame equipped with a clamshell furnace. Ultimately, superelasticity in uniaxial tension with clear plateau regions was demonstrated and characterized in these alloys at temperatures between 219 °C and 270 °C.

Massad, Jordan E.↗
NASA NTRS1972

Method for measuring static Young's modulus of tungsten to 1900 K

An instrument system was developed and tested to measure static Young's modulus of elasticity of refractory metals in tension at temperatures to 1900 K. The extensometer uses capacitance displacement sensors for measuring total elongation of a specimen and incorporates a unique high-resolution remote zero-adjusting mechanism. Details of a method for calibrating capacitance displacement sensors at temperatures to 800 K are included. The system was built to adapt to a vacuum furnace on a tensile machine and was tested on unalloyed tungsten rod specimens. The test results show that the system can measure the modulus of tungsten to 1900 K to within a precision of + or - 5 percent. The uncertainty of the measurement is estimated to be of the same order as the precision.

Harrigill, W. T., Jr.↗
NASA NTRS1995

Apparatus Measures Permeation Of Gases Through Coupons

Apparatus measures permeation of any variety of commercially available pure or mixed gases through polymeric or other material coupons of various thicknesses. Permeability measured at wide range of temperatures and pressures. Includes residual-gas-analyzer (RGA) sensor head and associated circuitry, and vacuum system. Also includes manifold with valves, through which gas of interest allowed to permeate through test coupon before traveling downstream to evacuated RGA sensor head. Temperature of test coupon monitored by thermocouple and maintained at specified value above ambient by use of electrical heating mantle or below ambient by use of bath of ethylene glycol, water, and dry ice.

Adam, Steven J.↗
NASA NTRS1996

Electronic and Interfacial Properties of PD/6H-SiC Schottky Diode Gas Sensors

Pd/SiC Schottky diodes detect hydrogen and hydrocarbons with high sensitivity. Variation of the diode temperature from 100 C to 200 C shows that the diode sensitivity to propylene is temperature dependent. Long-term heat treating at 425 C up to 140 hours is carried out to determine the effect of extended heat treating on the diode properties and gas sensitivity. The heat treating significantly affects the diode's capacitive characteristics, but the diode's current carrying characteristics are much more stable with a large response to hydrogen. Scanning Electron Microscopy and X-ray Spectrometry studies of the Pd surface after the heating show cluster formation and background regions with grain structure observed in both regions. The Pd and Si concentrations vary between grains. Auger Electron Spectroscopy depth profiles revealed that the heat treating promoted interdiffusion and reaction between the Pd and SiC dw broadened the interface region. This work shows that Pd/SiC Schottky diodes have significant potential as high temperature gas sensors, but stabilization of the structure is necessary to insure their repeatability in long-term, high temperature applications.

Chen, Liang-Yu↗
DOE OSTI2025

Origins of radiation-induced optical attenuation in neutron-irradiated single-crystal sapphire at elevated temperatures

Sapphire (α-Al 2 O 3 ) is a candidate fiber-optic sensor material for extreme temperature environments, potentially including those of nuclear reactors. However, its optical transmission under high-dose neutron irradiation is not well understood compared with that of conventional fused silica. This study examined dimensional changes, optical transmission, and irradiation-induced defects in neutron-irradiated α-Al 2 O 3 at temperatures of 298 °C to 688 °C and doses of 3.2 to 12 dpa. Although previous studies attributed radiation-induced attenuation (RIA) at the highest irradiation temperatures to increased optical scattering from radiation-induced voids, our findings indicate that scattering from neither voids nor dislocation loops can explain the measured attenuation. Instead, absorption due to aluminum vacancy centers appears more likely based on a comparison of the spectral features of the measured optical attenuation with previous literature. Significant c-axis swelling (5.51 % ± 0.83 %) was observed in the 12 dpa, 592 °C irradiated sample, much higher than earlier measurements, suggesting temperature sensor drift of 543 °C to 1,140 °C. Void patterning was predominantly observed along the a-axis, differing from previous studies on polycrystalline samples, which showed c-axis patterning. Dislocation loops evolved into network dislocations with increasing temperature and dose; voids formed within these structures, showing no size or density changes, indicating an atypical growth mechanism.

Neutron irradiation↗
DOE OSTI2022

Temperature and Dynamic Strain Measurements Using a Single SAWR Sensor

Dynamic strain sensing is relevant in numerous applications involving structural health monitoring, condition-based maintenance, operation efficiency preservation, and work environment safety. These sensors are particularly critical for high-temperature (HT) harsh-environment (HE) industries such as aerospace, automotive, power plants, and advanced manufacturing. In HT/HE, sensor implementation and measurement present challenges such as maintaining sensor stability, accounting for temperature cross-sensitivity, providing HT attachment, and packaging of the sensors and system. Surface acoustic wave resonator (SAWR) sensors can address these needs and offer additional benefits such as compact size and wireless interrogation capability. The SAWR sensitivity to dynamic strain is temperature dependent, making it necessary to measure the sensor temperature in order to use the correct dynamic strain calibration curve. In this work, a method for determining the temperature, dynamic strain magnitude, and dynamic strain spectral components using a single SAWR sensor is presented. Here, the established technique for determining operational temperature and dynamic strain magnitude/spectral components using only one SAWR simplifies the sensor measurement system, thus being very attractive for HT /HE applications.

47 OTHER INSTRUMENTATION↗
NASA NTRS2009

NASA Tech Briefs, January 2009

Tech Briefs are short announcements of innovations originating from research and development activities of the National Aeronautics and Space Administration. They emphasize information considered likely to be transferable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. Topics covered include: The Radio Frequency Health Node Wireless Sensor System; Effects of Temperature on Polymer/Carbon Chemical Sensors; Small CO2 Sensors Operate at Lower Temperature; Tele-Supervised Adaptive Ocean Sensor Fleet; Synthesis of Submillimeter Radiation for Spectroscopy; 100-GHz Phase Switch/Mixer Containing a Slot-Line Transition; Generating Ka-Band Signals Using an X-Band Vector Modulator; SiC Optically Modulated Field-Effect Transistor; Submillimeter-Wave Amplifier Module with Integrated Waveguide Transitions; Metrology System for a Large, Somewhat Flexible Telescope; Economical Implementation of a Filter Engine in an FPGA; Improved Joining of Metal Components to Composite Structures; Machined Titanium Heat-Pipe Wick Structure; Gadolinia-Doped Ceria Cathodes for Electrolysis of CO2; Utilizing Ocean Thermal Energy in a Submarine Robot; Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators; Alternative OTEC Scheme for a Submarine Robot; Sensitive, Rapid Detection of Bacterial Spores; Adenosine Monophosphate-Based Detection of Bacterial Spores; Silicon Microleaks for Inlets of Mass Spectrometers; CGH Figure Testing of Aspherical Mirrors in Cold Vacuums; Series-Coupled Pairs of Silica Microresonators; Precise Stabilization of the Optical Frequency of WGMRs; Formation Flying of Components of a Large Space Telescope; Laser Metrology Heterodyne Phase-Locked Loop; Spatial Modulation Improves Performance in CTIS; High-Performance Algorithm for Solving the Diagnosis Problem; Truncation Depth Rule-of-Thumb for Convolutional Codes; Efficient Method for Optimizing Placement of Sensors.

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