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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

High-efficiency 20 GHz traveling wave tube development for space communications

A 75 watt CW high efficiency helix TWT operating at 20 GHz was developed for satellite communication systems. The purpose was to extend the performance capabilities of helix TWTs by using recent technology developments. The TWT described is a unique design because high overall efficiency is obtained with a low perveance beam. In the past, low perveance designs resulted in low beam efficiencies. However, due to recent breakthoughs in diamond rod technology and in collector electrode materials, high efficiencies can now be achieved with low perveance beams. The advantage of a low perveance beam is a reduction in space charge within the beam which translates to more efficient collector operation. In addition, this design incorporates textured graphite electrodes which further enhance collector operation by suppressing backstreaming secondaries. The diamond supported helix circuit features low RF losses, high interaction impedance, good thermal handling capability and has been designed to compensate for the low perveance beam. One more discussed tube feature is the use of a velocity taper in the output helix that achieves low signal distortion while maintaining high efficiency.

Aldana, S. L.↗
DOE OSTI2024

In-Silico Analysis of High Refractive Index Materials Through Principles of Materials Design

The intent of the paper is to use specific principles of Materials Design that were developed and applied in the electronics industry for enabling understanding and design of improved high refractive index materials. Further, by combining first-principle based ab-initio, semiempirical interatomic potential methods, and machine learning approaches in conjunction with experimental data, we identified specific determinants of high refractive index materials, which can be critically applied for informing materials design and accelerating discovery. Specifically, it was demonstrated that chalcogenides and perovskites as bulk materials can exhibit higher refractive indices with appropriate engineering of specific aspects of the materials.

36 MATERIALS SCIENCE↗
NASA NTRS1978

Building Specifications

The building in the top photo is the new home of the National Permanent Savings Bank in Washington, D.C., designed by Hartman-Cox Architects. Its construction was based on a money-saving method of preparing building specifications which derived from NASA technology developed to obtain quality construction while holding down cost of launch facilities, test centers and other structures. Written technical specifications spell out materials and components to be used on construction projects and identify the quality tests each item must pass. Specifications can have major impact on construction costs. Poorly formulated specifications can lead to unacceptable construction which must be replaced, unnecessarily high materials costs, safety hazards, disputes and often additional costs due to delays and litigation. NASA's Langley Research Center developed a novel approach to providing accurate, uniform, cost-effective specifications which can be readily updated to incorporate new building technologies. Called SPECSINTACT, it is a computerized - system accessible to all NASA centers involved in construction programs. The system contains a comprehensive catalog of master specifications applicable to many types of construction. It enables designers of any structure to call out relevant sections from computer storage and modify them to fit the needs of the project at hand. Architects and engineers can save time by concentrating their efforts on needed modifications rather than developing all specifications from scratch. Successful use of SPECSINTACT has led to a number of spinoff systems. One of the first was MASTERSPEC, developed from NASA's experience by Production Systems for Architects and Engineers, Inc., an organization established by the American Institute of Architects. MASTERSPEC, used in construction of the bank building pictured, follows the same basic format as SPECSINTACT and can be used in either automated or manual modes. The striking appearance of the bank building shows that, while MASTERSPEC saves time and money, its use involves no sacrfice in architectural design freedom. The Naval Engineering Facilities Command employs an automated specifications system based on SPECSINTACT. The Public Buildings Service of the General Services Administration used SPECSINTACT as a starting point in a plan to make its guideline specifications available to architects and engineers on a nationwide computer network. Public Technology, Inc., a NASA Technology Application Team, is working with Production Systems for Architects and Engineers, Inc., to promote widespread use of the system by state and local governments for cost benefits to taxpayers.

Source record↗
DOE OSTI2020

Discovery of Rhombohedral NaIrO 3 Polymorph by In Situ High-Pressure Synthesis of High-Oxidation-State Materials Using Laser Heating in Diamond Anvil Cells

Here, we report a new in-situ synthesis method effective for discovery of high oxidation state materials using laser heated diamond anvil cells. The issue of chemical reduction during thermally induced phase transitions that occur spontaneously in a noble gas pressure transmitting media (PTM) can be overcome by thermal decomposition of an oxygen-rich solid PTM (NaCl + NaClO 3 ). To illustrate the technical challenges the method overcomes, we applied this new method for two known phase transitions from pentavalent A (I) B (V) O 3 perovskites to the post-perovskite structure. We successfully synthesized and quenched the two post-perovskites, NaOsO 3 and NaIrO 3 , to ambient conditions and furthermore, we report the discovery of a new low-pressure polymorph of NaIrO 3 , illustrating the high potential for new materials discovery. This new method will enable realization of new high oxidation state post-perovskites and can be applied for many other structure families in a P, T parameter space which is not easily accessible using conventional high-pressure synthesis methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2022

Premature Deaths in Africa Due to Particulate Matter Under High and Low Warming Scenarios

Sustainable development and climate change mitigation can provide enormous public health benefits via improved air quality, especially in polluted areas. We use the latest state-of-the-art composition-climate model simulations to contrast human exposure to fine particulate matter in Africa under a “baseline” scenario with high material consumption, population growth, and warming to that projected under a sustainability scenario with lower consumption, population growth, and warming. Evaluating the mortality impacts of these exposures, we find that under the low warming scenario annual premature deaths due to PM2.5 are reduced by roughly 515,000 by 2050 relative to the high warming scenario (100,000, 175,000, 55,000, 140,000, and 45,000 in Northern, West, Central, East, and Southern Africa, respectively). This reduction rises to ∼800,000 by the 2090s, though by that time much of the difference is attributable to the projected differences in population. By contrast, during the first half of the century benefits are driven predominantly by emissions changes. Depending on the region, we find large intermodel spreads of ∼25%–50% in projected future exposures owing to different physics across the ensemble of 6 global models. The spread of projected deaths attributable to exposure to fine particulate matter, including uncertainty in the exposure-response function, are reduced in every region to ∼20%–35% by the non-linear exposure-response function. Differences between the scenarios have an even narrower spread of ∼5%–25% and are highly statistically significant in all regions for all models. These results provide valuable information for policy-makers to consider when working toward climate change mitigation and sustainable development goals.

PM2.5↗
DOE OSTI2024

Assessment of wafer scale MoS 2 atomic layers grown by metal–organic chemical vapor deposition using organo-metal, organo-sulfide, and H 2 S precursors

Transition Metal Dichalcogenides (TMDs) are a unique class of materials that exhibit attractive electrical and optical properties which have generated significant interest for applications in microelectronics, optoelectronics, energy storage, and sensing. Considering the potential of these materials to impact such applications, it is crucial to develop a reliable and scalable synthesis process that is compatible with modern industrial manufacturing methods. Metal–organic chemical vapor deposition (MOCVD) offers an ideal solution to produce TMDs, due to its compatibility with large-scale production, precise layer control, and high material purity. Optimization of MOCVD protocols is necessary for effective TMD synthesis and integration into mainstream technologies. Additionally, improvements in metrology are necessary to measure the quality of the fabricated samples more accurately. In this work, we study MOCVD of wafer-scale molybdenum disulfide (MoS 2 ) utilizing two common chalcogen precursors, H 2 S and DTBS. We then develop a metrology platform for wafer scale samples quality assessment. For this, the coalesced films were characterized using Raman spectroscopy, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Kelvin probe force microscopy. We then correlate the structural analysis of these grown films with electrical performance by using aerosol jet printing to fabricate van der Pauw test structures and assess sheet resistance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2002

An Accurate Quartic Force Field, Fundamental Frequencies, and Binding Energy for the High Energy Density Material T(d)N4

The CCSD(T) method has been used to compute a highly accurate quartic force field and fundamental frequencies for all N-14 and N-15 isotopomers of the high energy density material T(sub d)N(sub 4). The computed fundamental frequencies show beyond doubt that the bands observed in a matrix isolation experiment by Radziszewski and coworkers are not due to different isotopomers of T(sub d)N(sub 4). The most sophisticated thermochemical calculations to date yield a N(sub 4) -> 2N(sub 2) heat of reaction of 182.22 +/- 0.5 kcal/mol at 0 K (180.64 +/- 0.5 at 298 K). It is hoped that the data reported herein will aid in the ultimate detection of T(sub d)N(sub 4).

Lee, Timothy J.↗
NASA NTRSDate not supplied

High Risk Spacecraft Materials Offgassing

NASA-STD-6001B, Determination of Offgassed Products (Test 7), provides the offgassing characteristics under standardized conditions for materials and assembled articles to be located within habitable spacecraft environments. Experience with Test 7 has found certain material types to be of higher risk for offgassing undesirable compounds aboard spacecraft than others. Formaldehyde and acrolein are historically high T value offgassed components of the offgassed compound target list because they have low spacecraft maximum allowable concentration (SMAC) values assigned by the JSC Toxicology Group. Carbon disulfide, benzene, acrylonitrile, and furan are additional target compounds of concern due to their lower thresholds of toxicity as determined by the JSC Toxicology Group. Materials offgassing siloxanes are also of concern due to their degradation effects on environmental control and life support system (ECLSS) components and performance. Spacecraft materials and articles defined in this manuscript as high risk were identified after examining and condensing data for these compounds of concern from approximately 3000 tests performed over 30 years. Summaries of high risk material and article types based on highest Multi-Purpose Crew Vehicle (MPCV) T values are also presented. Historical analysis shows high risk components are produced largely from test materials and articles in the general categories of electronic/powered components, foams, paints/coatings/films, adhesives/tapes, epoxy/resins, liquids/gels, Nomex® with surface treatments, markers/pens/inks, dry film lubricants, thermoplastics, hygiene items (deodorants, lip balms), and silicone rubber. These data are intended to be a resource for spacecraft materials and processes managers, designers, and toxicologists. High risk materials and articles intended for use aboard spacecraft should be tested in accordance with NASA-STD-6001B Test 7.

Vanessa D Buchanan↗
DOE OSTI2020

Science and Technology of High Performance Ferritic (HiperFer) Stainless Steels

Future, flexible thermal energy conversion systems require new, demand-optimized high-performance materials. The High performance Ferritic (HiperFer) stainless steels, under development at the Institute of Microstructure and Properties of Materials (IEK-2) at Forschungszentrum Jülich GmbH in Germany, provide a balanced combination of fatigue, creep and corrosion resistance at reasonable price. This paper outlines the scientific background of alloy performance development, which resulted in an age-hardening ferritic, stainless steel grade. Furthermore, technological properties are addressed and the potential concerning application is estimated by benchmarking versus conventional state of the art materials.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nonlinear refraction and absorption properties of optical materials for high-peak-power long-wave-infrared lasers

Optical materials transparent in the CO 2 laser wavelength range have been evaluated regarding their suitability for components in ultrashort-pulse (≤ a few ps), high-peak-power (≥ a few TW) long-wave infrared (LWIR) lasers. We provide values for the nonlinear refractive index ( n 2 ) for seventeen materials, and onsets for nonlinear absorption for eleven materials. Characterizations were performed using a 2 ps laser pulse at λ =9.2 μ m. This paper methodically presents the newly acquired data in conjunction with existing literature on linear optical properties, establishing it as a comprehensive reference for designing high-peak-power LWIR laser systems.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Meter-scale van der Waals films manufactured via one-step roll printing

A weak van der Waals (vdW) force in layered materials enables their isolation into thin flakes through mechanical exfoliation while sustaining their intrinsic electronic and optical properties. Here, we introduce a universal roll-printing method capable of producing vdW multilayer films on wafer-to-meter scale. This process uses sequential exfoliation and transfer of layered materials from the powder sources to target substrates through a repeated rolling of a cylindrical metal drum. We achieve uniformly coated films with a library of vdW powders on various mechanically rigid and flexible substrates. The printed films are configured into different devices including light-emitting diodes and photodetectors. The presented technique offers substantial benefits in terms of cost efficiency and a low thermal budget while offering high material quality.

36 MATERIALS SCIENCE↗
NASA NTRS1994

Laminated thermoplastic composite material from recycled high density polyethylene

The design of a materials-science, educational experiment is presented. The student should understand the fundamentals of polymer processing and mechanical property testing of materials. The ability to use American Society for Testing and Materials (ASTM) standards is also necessary for designing material test specimens and testing procedures. The objectives of the experiment are (1) to understand the concept of laminated composite materials, processing, testing, and quality assurance of thermoplastic composites and (2) to observe an application example of recycled plastics.

Liu, Ping↗
DOE OSTI2023

Smoothing tool design and performance during subaperture glass polishing

During subaperture tool grinding and polishing, overlaps of the tool influence function can result in undesirable mid-spatial frequency (MSF) errors in the form of surface ripples, which are often corrected using a smoothing polishing step. Here, in this study, flat multi-layer smoothing polishing tools are designed and tested to simultaneously (1) reduce or remove MSF errors, (2) minimize surface figure degradation, and (3) maximize the material removal rate. A time-dependent convergence model in which spatial material removal varies with a workpiece-tool height mismatch, combined with a finite element mechanical analysis to determine the interface contact pressure distribution, was developed to evaluate various smoothing tool designs as a function of tool material properties, thicknesses, pad textures, and displacements. An improvement in smoothing tool performance is achieved when the gap pressure constant, $\overline{h}$ (which describes the inverse rate at which the pressure drops with a workpiece-tool height mismatch), is minimized for smaller spatial scale length surface features (namely, MSF errors) and maximized for large spatial scale length features (i.e., surface figure). Five specific smoothing tool designs were experimentally evaluated. A two-layer smoothing tool using a thin, grooved IC1000 polyurethane pad (with a high elastic modulus, E pad =360 MPa ), thicker blue foam (with an intermediate modulus, E foam =5.3 MPa ) underlayer, and an optimized displacement (d t =1 mm ) provided the best overall performance (namely, high MSF error convergence, minimal surface figure degradation, and high material removal rate).

47 OTHER INSTRUMENTATION↗
NASA NTRS1971

Multilayer high performance insulation materials

A number of tests are required to evaluate both multilayer high performance insulation samples and the materials that comprise them. Some of the techniques and tests being employed for these evaluations and some of the results obtained from thermal conductivity tests, outgassing studies, effect of pressure on layer density tests, hypervelocity impact tests, and a multilayer high performance insulation ambient storage program at the Kennedy Space Center are presented.

Stuckey, J. M.↗
DOE OSTI2025

In Situ MOVPE Smoothing of Acoustically Spalled GaAs for Substrate Reuse

High material costs, especially for substrates, have limited the widespread adoption of III-V photovoltaics. A potential to reduce this cost is to reuse the III-V substrate via acoustic spalling, however this technique can leave a rough surface, hindering subsequent device performance. This research investigates the potential of using metalorganic vapor-phase epitaxy growth as a buffer layer to smooth the surface of acoustically spalled germanium and gallium arsenide (GaAs) substrates for improved III-V photovoltaic cell yield and performance, while retaining the maximum number of reuses of a substrate. Three potential smoothing layers were explored: lightly doped C:GaAs, highly doped Se:GaInP, and lightly doped Se:GaInP. C:GaAs showed the most promise as a smoothing layer, while Se:GaInP tended to conform to the underlying morphology, potentially increasing roughness in some areas. Utilizing 5 ..mu..m of C:GaAs as a planarizing buffer increased the average efficiency (without an antireflection coating) from an as-spalled baseline from 2.1% to 4.9% and performing a 5-min 30 degrees C 8:1:1 H2SO4:H2O2:H2O etch prior to a 5 ..mu..m of C:GaAs as a planarizing buffer further increased efficiency to 11.1%.

14 SOLAR ENERGY↗
NASA NTRS1983

Impact reactivity of materials at very high oxygen pressure

The requirements for impact testing of materials in an oxygen atmosphere at pressures from 82.7 MPa (12,000 psi) to 172 MPa (25,000 psi) were evaluated. The impact tester system was evaluated for potential pressure increases from 69 MPa (10,000 psi) to 82.7 MPa (12,000 psi). The low pressure oxygen and nitrogen systems, the impact tower, the impact test cell, and the high pressure oxygen system were evaluated individually. Although the structural integrity of the impact test cell and the compressor were sufficient for operation at 82.7 MPa (12,000 psi), studies revealed possible material incompatibility at that pressure and above. It was recommended that if a component should be replaced for 82.7 MPa (12,000 psi) operation the replacement should meet the final objectives of 172 MPa (25,000 psi). Recommended changes in the system include; use of Monel 400 for pressures above 82.7 MPa (12,000 psi), use of bellows to replace the seal in the impact tester, use of a sapphire window attached to a fiber optic for event sensing, and use of a three diaphragm compressor.

Connor, H. W.↗