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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 NTRS2018

Channel Wall Nozzle Manufacturing and Hot-Fire Testing Using a Laser Wire Direct Closeout Technique for Liquid Rocket Engines

A regeneratively-cooled nozzle for liquid rocket engine applications is a significant cost of the overall engine due to the complexities of manufacturing a large thin-walled structure that must operate in extreme temperature and pressure environments. The National Aeronautics and Space Administration (NASA) has been investigating and advancing methods for fabrication of liquid rocket engine channel wall nozzles to realize further cost and schedule improvements over traditional techniques. The methods being evaluated are targeting increased scale required for current NASA and commercial space programs. Several advanced rapid fabrication methods are being investigated for forming of the inner liner, producing the coolant channels, closeout of the coolant channels, and fabrication of the manifolds. NASA's Marshall Space Flight Center (MSFC) has completed process development and subscale hot-fire testing of a series of these advanced fabrication channel wall nozzle technologies to gather performance data in a relevant environment. The primary fabrication technique being discussed in this paper is Laser Wire Direct Closeout (LWDC). This process has been developed to significantly reduce the time required for closeouts of regeneratively-cooled slotted liners. It allows for channel closeout to be formed in place in addition to the structural jacket without the need for channel fillers or complex tooling. Additional technologies were also tested as part of this program including water jet milling and arc-based additive manufacturing deposition. Each nozzle included different fabrication features, materials, and methods to demonstrate durability in a hot-fire environment. The results of design, fabrication, and hot-fire testing are discussed in this paper.

Gradl, Paul R.↗
NASA NTRS2005

Siderophile Element Profile Measurements in Iron Meteorites Using Laser Ablation ICP-MS

Understanding the behaviour of siderophile elements during cooling of iron meteorites can lead to insight into the general thermal histories of the meteorites as well as their respective parent bodies. Traditionally trace element analyses in meteorites have been done using techniques that only measure the average concentration in each phase. With these methods, all of the spatial information with respect to the distribution of an element within one phase is lost. Measuring concentration profiles of trace elements in meteorites is now possible, with the advent of high-resolution analytical techniques such as laser ablation, inductively coupled plasma mass spectrometry (LA-ICP-MS) with spatial resolution <20 microns. [e.g. 1,2] and secondary ion mass spectrometry [3]. These profiles can give more insight into both the partitioning and diffusive behavior of siderophile elements in metal systems relevant to iron meteorites, as well as parent body cooling rates.

Watson, H. C.↗
NASA NTRS1984

A redetermination of the succinonitrile-water phase diagram

The phase diagram of the water/succinonitrile system often used in modeling binary metallic alloys is determined experimentally using a laser scattering method. Triply distilled and zone-refined succinonitrile is placed in a jacketed water-cooled vessel with a magnetic mixer and a copper-constantan thermocouple, and the melting point is determined under vacuum and under Ar by observing the response of a photodiode placed opposite a laser source as the chamber is cooled and reheated. Then water is added, and the eutectic and monotectic temperatures and the entire phase diagram are determined under Ar. The results are presented in a table and graph and compared to those of Schreinemakers (1897): significant discrepancies are noted and attributed to impurities in the succinonitrile used by Schreinemakers. The importance of accurate phase diagrams for modeling binary alloys is stressed.

Smith, J. E., Jr.↗
NASA NTRS1992

Nonequilibrium synthesis of NbAl3 and Nb-Al-V alloys by laser cladding. I - Microstructure evolution

The evolution of the microstructure in NbAl3 synthesized by a laser cladding technique (a rapid solidification process, with cooling rates up to 10 exp 6 C/sec) is investigated, and the phases are identified using convergent beam electron diffraction. Two new metastable phases were identified and characterized in detail. The effect of adding V on the final microstructure was also investigated, and the various phase chemistries and the partitioning of different elements into different phases were studied.

Sircar, S.↗
NASA NTRS1996

Hot Carrier Dynamics in the X Valley in Si and Ge Measured by Pump-IR-Probe Absorption Spectroscopy

Si is the semiconductor of choice for nanoelectronic roadmap into the next century for computer and other nanodevices. With growing interest in Si, Ge, and Si(sub m)Ge(sub n) strained superlattices, knowledge of the carrier relaxation processes in these materials and structures has become increasingly important. The limited time resolution for earlier studies of carrier dynamics in Ge and Si, performed using Nd:glass lasers, was not sufficient to observe the fast cooling processes. In this paper, we present a direct measurement of hot carrier dynamics in the satellite X valley in Si and Ge by time-resolved infrared(IR) absorption spectroscopy, and show the potential of our technique to identify whether the X valley is the lowest conduction valley in semiconductor materials and structures.

Wang, W. B.↗
NASA NTRS2014

Damage Characterization of EBC-SiCSiC Ceramic Matrix Composites Under Imposed Thermal Gradient Testing

Due to their high temperature capabilities, Ceramic Matrix Composite (CMC) components are being developed for use in hot-section aerospace engine applications. Harsh engine environments have led to the development of Environmental Barrier Coatings (EBCs) for silicon-based CMCs to further increase thermal and environmental capabilities. This study aims at understanding the damage mechanisms associated with these materials under simulated operating conditions. A high heat-flux laser testing rig capable of imposing large through-thickness thermal gradients by means of controlled laser beam heating and back-side air cooling is used. Tests are performed on uncoated composites, as well as CMC substrates that have been coated with state-of-the-art ceramic EBC systems. Results show that the use of the EBCs may help increase temperature capability and creep resistance by reducing the effects of stressed oxidation and environmental degradation. Also, the ability of electrical resistance (ER) and acoustic emission (AE) measurements to monitor material condition and damage state during high temperature testing is shown; suggesting their usefulness as a valuable health monitoring technique. Micromechanics models are used to describe the localized stress state of the composite system, which is utilized along with ER modeling concepts to develop an electromechanical model capable of characterizing material behavior.

protective coatings (nonmetallic)↗
NASA NTRS1997

Super-Compact Laser

Microcosm, Inc. produced the portable Farfield-2 laser for field applications that require high power pulsed illumination. The compact design was conceived through research at Goddard Space Flight Center on laser instruments for space missions to carry out geoscience studies of Earth. An exclusive license to the key NASA patent for the compact laser design was assigned to Microcosm. The FarField-2 is ideal for field applications, has low power consumption, does not need water cooling or gas supplies, and produces nearly ideal beam quality. The properties of the laser also make it effective over long distances, which is one reason why NASA developed the technology for laser altimeters that can be toted aboard spacecraft. Applications for the FarField-2 include medicine, biology, and materials science and processing, as well as diamond marking, semiconductor line-cutting, chromosome surgery, and fluorescence microscopy.

Source record↗
NASA NTRS2005

Adding GaAs Monolayers to InAs Quantum-Dot Lasers on (001) InP

In a modification of the basic configuration of InAs quantum-dot semiconductor lasers on (001)lnP substrate, a thin layer (typically 1 to 2 monolayer thick) of GaAs is incorporated into the active region. This modification enhances laser performance: In particular, whereas it has been necessary to cool the unmodified devices to temperatures of about 80 K in order to obtain lasing at long wavelengths, the modified devices can lase at wavelengths of about 1.7 microns or more near room temperature. InAs quantum dots self-assemble, as a consequence of the lattice mismatch, during epitaxial deposition of InAs on ln0.53Ga0.47As/lnP. In the unmodified devices, the quantum dots as thus formed are typically nonuniform in size. Strainenergy relaxation in very large quantum dots can lead to poor laser performance, especially at wavelengths near 2 microns, for which large quantum dots are needed. In the modified devices, the thin layers of GaAs added to the active regions constitute potential-energy barriers that electrons can only penetrate by quantum tunneling and thus reduce the hot carrier effects. Also, the insertion of thin GaAs layer is shown to reduce the degree of nonuniformity of sizes of the quantum dots. In the fabrication of a batch of modified InAs quantum-dot lasers, the thin additional layer of GaAs is deposited as an interfacial layer in an InGaAs quantum well on (001) InP substrate. The device as described thus far is sandwiched between InGaAsPy waveguide layers, then further sandwiched between InP cladding layers, then further sandwiched between heavily Zn-doped (p-type) InGaAs contact layer.

Qiu, Yueming↗
NASA NTRS1984

High Speed Crystal Growth by Q-switched Laser Melting

The modification of the structural and electrical properties of semiconductors short radiation pulses obtained from Q-switched lasers is described. These modifications are accomplished by high heating and cooling rates. This processing revealed novel crystal growth and high speed resolidification phenomena. The behavior of semiconductor Si is analyzed. The annealing process typically employs short pulses of radiation in or near the visible region of the spectrum. The Q-switched ruby and Nd-YAG lasers are commonly used and these are sometimes mode locked to reduce the pulse length still further. Material to be annealed can be processed with a single large area radiation spot. Alternatively, a small radiation spot size can be used and a large sample area is covered by overlapping irradiated regions.

Cullis, A. G.↗
NASA NTRS1987

Pulsed source of energetic atomic oxygen

A pulsed high flux source of nearly monoenergetic atomic oxygen was designed, built, and successfully demonstrated. Molecular oxygen at several atmospheres pressure is introduced into an evacuated supersonic expansion nozzle through a pulsed molecular beam valve. An 18 J pulsed CO2 TEA laser is focused to intensities greater than 10(9) W/sq cm in the nozzle throat to generate a laser-induced breakdown. The resulting plasma is heated in excess of 20,000 K by a laser supported detonation wave, and then rapidly expands and cools. Nozzle geometry confines the expansion to provide rapid electron-ion recombination into atomic oxygen. Average O atom beam velocities from 5 to 13 km/s were measured at estimated fluxes to 10(18) atoms per pulse. Preliminary materials testing has produced the same surface oxygen enrichment in polyethylene samples as obtained on the STS-8 mission. Scanning electron microscope examinations of irradiated polymer surfaces reveal an erosion morphology similar to that obtained in low Earth orbit, with an estimated mass removal rate of approx. 10(-24) cu cm/atom. The characteristics of the O atom source and the results of some preliminary materials testing studies are reviewed.

Caledonia, George E.↗
NASA NTRS1997

Temperature Dependence of the Collisional Removal of O2(A(sup 3)Sigma(sup +)(sub u), upsilon=9 ) with O2 and N2

The temperature dependence of the collisional removal of O2 molecules in the upsilon = 9 level of the A(sup 3)Sigma(sup +)(sub u) electronic state has been studied for the colliders O2 and N2, over the temperature range 150 to 300 K. In a cooled flow cell, the output of a pulsed dye laser excites the O2 to the upsilon = 9 level of the A(sup 3)Sigma(sup +)(sub u) state, and the output of a time-delayed second laser monitors the temporal evolution of this level via a resonance-enhanced ionization. We find the u thermally averaged removal cross section for O2 collisions is constant (approx. 10 A(sup 2)) between room temperature and 200 K, then increases rapidly with decreasing temperature, doubling by 150 K. In contrast, the N2 cross section at 225 K is approx. 8% smaller and gradually increases to a value at 150 K that is approx. 60% larger than the room temperature value. The difference between the temperature dependence of the O2 and N2 collision cross section implies that the removal by oxygen becomes more important at the lower temperatures found in the mesosphere, but removal by N2 still dominates.

Hwang, Eunsook S.↗
NASA NTRS2009

All-Solid-State UV Transmitter Development for Ozone Sensing Applications

In this paper, recent progress made in the development of an all-solid-state UV transmitter suitable for ozone sensing applications from space based platforms is discussed. A nonlinear optics based UV setup based on Rotated Image Singly Resonant Twisted Rectangle (RISTRA) optical parametric oscillator (OPO) module was effectively coupled to a diode pumped, single longitudinal mode, conductively cooled, short-pulsed, high-energy Nd:YAG laser operating at 1064 nm with 50 Hz PRF. An estimated 10 mJ/pulse with ~10% conversion efficiency at 320 nm has been demonstrated limited only by the pump pulse spatial profile. The current arrangement has the potential for obtaining greater than 200 mJ/pulse. Previously, using a flash-lamp pumped Nd:YAG laser with round, top-hat profile, up to 24% IR-UV conversion efficiency was achieved with the same UV module. Efforts are underway to increase the IR-UV conversion efficiency of the all solid-state setup by modifying the pump laser spatial profile along with incorporating improved OPO crystals.

Prasad, Narasimha S.↗
NASA NTRS2019

In-situ Mechanical Neutron Diffraction Loading Characteristics of GRCop-84 Fabricated by SLM

GRCop-84 is a precipitation strengthened alloy composed of Cu-8Cr-4Nb at % with Cr2Nb precipitates that provide dispersion and precipitation strengthening characteristics and limited solubility in the Cu matrix. The particle role of Cr2Nb(C15Laves) is unusual only contributing 1/3 of strengthening at high temperatures while the matrix provides the remainder. The particles mechanically and thermally stabilize the matrix retaining purity and preventing coarsening and loss of strength. At high temperatures (50-85%TmCu), GRCop-84 provides the best thermal and mechanical properties of available alloys. GRCop-84 is currently in development for reusable launch vehicles including the Space Launch System (SLS) with a focus on fabrication with additive manufacturing (AM) techniques. GRCop-84 is an optimal material for consolidating with AM. The base material is costly, the production times are long, and more geometry control can considerably improve cooling efficiency. Development of AMGR Cop-84 with selective laser melting (SLM) has rapidly progressed due to ease of printing and limited operator adjustment between builds, but the necessary knowledge-base of thermal history and stress state during builds is still under development.

Minneci, R.↗
NASA NTRS1995

Laser-Induced Incandescence Calibration via Gravimetric Sampling

Various beam imaging and/or sheet forming optics delivered light at 1064 nm from a pulsed Nd:YAG laser for use either as a beam of 3 mm radius or as a laser sheet. Imaging measurements were performed with a grated intensified array camera equipped with an ultraviolet f4.5 lens and a 40 mm extension tube. Point measurements were performed using an ultraviolet 250 mm focal length lens to collect and focus the laser induced incandescence (LII) signal into a 1 meter long quartz optical fiber which directed the LII signal to a 1/4 meter monochromator. An aperture preceding the lens restricted the signal collection region to 1 cm along the laser beam at the center of the gravimetric chimney. Signals from the PMT were processed by a boxcar integrator whereas the images were captured digitally using a frame-grabber with 16 MByte of on-board memory. Both 'point' and planar measurements were made with detector gates of 250 ns to minimize possible morphology bias in collection of the LII signal. Additionally, the imaging measurements were performed with broadband spectral collection of the LII signal to maximize the signal and again minimize any potential effects of morphology dependent heating and/or cooling rates. Digital delay generators controlled the firing of he laser, detector gates and data acquisition. Neutral density filters were used for both sets of measurements to maintain signal levels within linear dynamic ranges of the detectors, the range being determined prior to experiments.

VanderWal, R. L.↗
NASA NTRS2003

Evaporative Cooling in a Holographic Atom Trap

We present progress on evaporative cooling of Rb-87 atoms in our Holographic Atom Trap (HAT). The HAT is formed by the interference of five intersecting YAG laser beams: atoms are loaded from a vapor-cell MOT into the bright fringes of the interference pattern through the dipole force. The interference pattern is composed of Talbot fringes along the direction of propagation of the YAG beams, prior to evaporative cooling each Talbot fringe contains 300,000 atoms at 50 micro-K and peak densities of 2 x 10(exp 14)/cu cm. Evaporative cooling is achieved through adiabatically decreasing the intensity of the YAG laser. We present data and calculations covering a range of HAT geometries and cooling procedures.

Newell, Raymond↗
NASA NTRS2018

Hybrid Additive Manufacturing Deposition and Selective Laser Melting Techniques Applied to Copper-Alloy Liquid Rocket Engine Combustion Chambers

Virgin Orbit and the NASA Marshall Space Flight Center have partnered to fabricate a small, multi-metallic, regeneratively cooled thrust chamber by leveraging the strengths of two different types of additive manufacturing: Direct Metal Laser Sintering (DMLS) for the copper alloy liner and blown powder Directed Energy Deposition (DED) for the Inconel structural jacket. The DED is being developed using Virgin Orbit's DMG Mori Seiki hybrid additive/subtractive machining center to further enable unique processing and further cost savings. The materials chosen are preferred for high performance thrust chamber applications, representing a significant advancement from the compromises typically made in the production of metal 3D printed thrust chambers for rocket engines. The 1.2K-lbf thrust article is a 16" tall, 3" diameter design modified for this effort to be regeneratively cooled with water and hot fired using a RP-1/LOX pintle-style development injector from Virgin Orbit's NewtonFour upper stage engine. The thrust chamber was tested at Virgin Orbit's Necker test site in Mojave, California. Results from this test campaign are reported in addition to information characterizing the liner, jacket, and bimetallic diffusion layer materials. This paper will also highlight some of the future bimetallic thrust chamber developments that MSFC and Virgin Orbit will complete under a recently awarded NASA contract.

Zagorski, Kevin↗
NASA NTRS1979

High power phase locked laser oscillators

The feasibility of mechanizing an adaptive array of independent laser oscillators for generation of a high power coherent output was experimentally investigated. Tests were structured to evaluate component/system requirements for delivery of energy to a low-earth orbit satellite. Initial experiments addressed the control issues of phase locking unstable resonators at low power levels. A successful phase lock demonstration formed the basis for the design and fabrication of the high power, water-cooled, control mirror subsequently installed in the NASA LeRC high power laser. Tests were performed to characterize the operational limits of the laser system and included quantitative assessment of the frequency stability, noise sources, and optical properties of the beam.

Hayes, C. L.↗
NASA NTRS1997

Machine Phase Fullerene Nanotechnology: 1996

NASA has used exotic materials for spacecraft and experimental aircraft to good effect for many decades. In spite of many advances, transportation to space still costs about $10,000 per pound. Drexler has proposed a hypothetical nanotechnology based on diamond and investigated the properties of such molecular systems. These studies and others suggest enormous potential for aerospace systems. Unfortunately, methods to realize diamonoid nanotechnology are at best highly speculative. Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically relatively accessible and of great aerospace interest. Machine phase materials are (hypothetical) materials consisting entirely or in large part of microscopic machines. In a sense, most living matter fits this definition. To begin investigation of fullerene nanotechnology, we used molecular dynamics to study the properties of carbon nanotube based gears and gear/shaft configurations. Experiments on C60 and quantum calculations suggest that benzyne may react with carbon nanotubes to form gear teeth. Han has computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Results suggest that rotation can be converted to rotating or linear motion, and linear motion may be converted into rotation. Preliminary results suggest that these mechanical systems can be cooled by a helium atmosphere. Furthermore, Deepak has successfully simulated using helical electric fields generated by a laser to power fullerene gears once a positive and negative charge have been added to form a dipole. Even with mechanical motion, cooling, and power; creating a viable nanotechnology requires support structures, computer control, a system architecture, a variety of components, and some approach to manufacture. Additional information is contained within the original extended abstract.

Globus, Al↗