Method of directing a laser beam with very high accuracy
System will collimate and direct an argon laser beam with high angular tracking accuracy at objects on the moons surface. It can be adapted to missile and satellite tracking.
Allen, L. H.↗
SEARCH · Engineering Papers
Results for “laser directionality”
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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NASA direct detection laser diode driver
TRW has developed a prototype driver circuit for GaAs laser diodes as part of the NASA/Goddard Space Flight Center's Direct Detection Laser Transceiver (DDLT) program. The circuit is designed to drive the laser diode over a range of user-selectable data rates from 1.7 to 220 Mbps, Manchester-encoded, while ensuring compatibility with 8-bit and quaternary pulse position modulation (QPPM) formats for simulating deep space communications. The resulting hybrid circuit has demonstrated 10 to 90 percent rise and fall times of less than 300 ps at peak currents exceeding 100 mA.
Seery, B. D.↗
Satellite Power System (SPS) laser studies. Volume 2: Meteorological effects on laser beam propagation and direct solar pumped lasers for the SPS
The primary emphasis of this research activity was to investigate the effect of the environment on laser power transmission/reception from space to ground. Potential mitigation techniques to minimize the environment effect by a judicious choice of laser operating parameters was investigated. Using these techniques, the availability of power at selected sites was determined using statistical meteorological data for each site.
Beverly, R. E., III↗
Experimental Characterization of Surface Roughness and Geometric Evaluations of Thin-Wall Laser Powder Directed Energy Deposition
Additive Manufacturing (AM) has offered many new design and manufacturing opportunities for components across various industries. As AM evolves there is a need to better understand outputs of the process including geometric limitations and surface roughness based on specific application requirements. One possible application area of AM are components using thin-wall (<2 mm) microchannel heat exchangers for subsystems across aerospace, and industrial applications. AM offers the opportunity to significantly reduce the cost and lead time associated with fabricating these complex parts with internal features such as an array of cooling channels. Laser Powder Bed Fusion (L-PBF) has been continuously demonstrated as a technique to fabricate heat exchangers with internal geometric complexities. However, L-PBF is limited in the scale at which parts can be fabricated. Laser Powder Directed Energy Deposition (LP-DED) has been demonstrated as an AM technology to significantly increase the scale of which thin-wall microchannel heat exchangers could be manufactured. Successful deployment of the LP-DED technology requires critical understanding of the resulting features from the build process. Surface roughness is one of the critical areas that effects the friction factor and pressure drop within a heat exchanger and must be well understood. This presentation will provide an overview of the characterization work completed to understand the LP-DED process for thin-walls representative of hydrogen resistant alloy NASA HR-1 that would be used in a Hydrogen-environment application. An overview of the experiments conducted with varying LP-DED parameters, evaluation of various geometric channel and geometric build features and resulting surface finish will be provided along with a summary of conclusions from these experiments. Results indicate that powder size is a major contributor and surface roughness varies between closed channel shapes and external surfaces.
Directed Energy Deposition↗
Nondestructive Evaluation of the J-2X Direct Metal Laser Sintered Gas Generator Discharge Duct
The J-2X program at NASA's Marshall Space Flight Center (MSFC) procured a direct metal laser sintered (DMLS) gas generator discharge duct from Pratt & Whitney Rocketdyne and Morris Technologies for a test program that would evaluate the material properties and durability of the duct in an engine-like environment. DMLS technology was pursued as a manufacturing alternative to traditional techniques, which used off nominal practices to manufacture the gas generator duct's 180 degree turn geometry. MSFC's Nondestructive Evaluation (NDE) Team performed radiographic, ultrasonic, computed tomographic, and fluorescent penetrant examinations of the duct. Results from the NDE examinations reveal some shallow porosity but no major defects in the as-manufactured material. NDE examinations were also performed after hot-fire testing the gas generator duct and yielded similar results pre and post-test and showed no flaw growth or development.
Esther, Elizabeth A.↗
Bimetallic Channel Wall Nozzle Development and Hot-Fire Testing Using Additively Manufactured Laser Wire Direct Closeout Technology
NASA has been developing and advancing regeneratively-cooled channel wall nozzle technology for liquid rocket engines to reduce cost and schedules associated with fabrication. One of the primary methods being advanced is Laser Wire Direct Closeout (LWDC). LWDC was developed to provide an additively manufactured laser deposited closeout of the coolant channels that also forms the structural jacket in-situ. This technique has been previously demonstrated through process development and hot-fire testing on a series of subscale nozzles at NASA Marshall Space Flight Center. The hot-fire test articles were fabricated using monolithic alloys to simplify the fabrication process. Ongoing research is being conducted to further expand use of this process for increased scale and bimetallic or multi-alloy options. The use of multi-alloys is desired to fully optimize the combination of materials in the radial and axial directions to reduce overall weight of the nozzle and allow for higher thermal and structural margins on the channel wall nozzle. NASA recently completed process development and hot-fire testing of a series of channel wall nozzles that incorporate a copper-alloy as the hotwall liner material and a superalloy and combination thereof for the structural jacket using the LWDC technique. The fabrication process was further advanced by using a multi-alloy axial joint using explosive bonding integrating a copper-alloy at the forward end of the nozzle hotwall and a stainless-alloy for the remaining length. A third alloy was then used for the channel closeout using the LWDC process. This paper will describe the process development using the LWDC process for channel closeout utilizing the multi-alloys, hardware design and results from hot-fire testing on subscale multi-alloy LWDC channel cooled nozzles.
Gradl, Paul↗
Direction sensitive laser velocimeter
A laser velocimeter is described which determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mixed with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90 deg, mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by 90 deg and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.
Franke, J. M.↗
Thin-wall Internal Channel Geometry and Surface Enhancements for Heat Exchangers using Laser Powder Directed Energy Deposition
Additive Manufacturing (AM) has offered many new design and manufacturing opportunities for components across various industries. As AM evolves there is a need to better understand outputs of the process including geometric limitations, surface texture, and post-processing surface enhancements for specific application requirements. One possible application area of AM are components using thin-wall (~1 mm) microchannel heat exchangers for subsystems across aerospace and industrial applications. Laser Powder Bed Fusion (L-PBF) is a common process for complex internal channels but the build diameter is limited to approximately 600 mm. Laser Powder Directed Energy Deposition (LP-DED) is being evaluated to produce thin-wall microchannel heat exchangers at scales beyond the L-PBF process. Successful deployment of the LP-DED technology requires characterization of geometric features from the process and potential improvements to the surface using post-processing. Surface texture, inclusive of roughness and waviness, is one of the critical attributes of AM that effects the friction factor and pressure drop within a heat exchanger and lacks data for the LP-DED process. This presentation will provide an overview of the characterization work completed of the LP-DED process for thin-walls and small channel geometry representative of various high performance alloys including NASA HR-1 and GRCop-42. An overview of the experiments conducted with varying LP-DED parameters, evaluation of various internal channel geometry, geometric build features, and resulting surface texture will be provided along with a summary of conclusions from these experiments. This study presents characterization of 2.5 mm microchannels using LP-DED, mechanisms that cause the surface texture which include powder adherence and material droop, and angled walls have a significant impact on the thickness and surface texture. Results will also be presented on various surface enhancement processes that allow for tuning of the wetting surface for friction factor, heat transfer, or fatigue life performance requirements.
Additive Manufacturing↗
Al6061-RAM2 Development and Hot-Fire Testing using Additive Manufacturing Laser Powder Directed Energy Deposition for Liquid Rocket Engine Channel-Cooled Nozzles
Aluminum 6061-RAM2 is a high-strength aluminum feedstock developed for additive manufacturing (AM)processes. This alloy leverages Reactive Additive Manufacturing (RAM) technology. The RAM aluminum alloys were developed to be weldable—therefore printable—while equaling or exceeding strength properties of high strength wrought aluminum alloys. NASA and industry partners developed Laser Powder Directed Energy Deposition (LP-DED)additive manufacturing of Al6061-RAM2 for use in aerospace applications. Efforts included establishing build parameters, characterizing the alloy, fabricating components, and completing hot-fire testing of complex internal channel-cooled nozzles. These efforts are to address the growing need for large-scale parts using high-performance light-weight materials. Two rocket engine nozzles were fabricated using LP-DED Al6061-RAM2 that included integral cooling channels. The Al6061-RAM2 has completed process development and initial properties were established. This paper provides an overview of the LP-DED process development, material characterization and properties, component manufacturing, supplemental development, and hot-fire testing. Results from hot-fire testing are provided for a lander-class 31kN (7,000lbf)thrust engine using Liquid Oxygen (LOX)/Liquid Hydrogen(LH2) and LOX/Methane(LCH4).
Al6061-RAM2↗
Al6061-RAM2 Development and Hot-Fire Testing using Additive Manufacturing Laser Powder Directed Energy Deposition for Liquid Rocket Engine Channel-Cooled Nozzles
Aluminum 6061-RAM2 is a high-strength aluminum feedstock developed for additive manufacturing (AM)processes. This alloy leverages Reactive Additive Manufacturing (RAM) technology. The RAM aluminum alloys were developed to be weldable—therefore printable—while equaling or exceeding strength properties of high strength wrought aluminum alloys. NASA and industry partners developed Laser Powder Directed Energy Deposition (LP-DED)additive manufacturing of Al6061-RAM2 for use in aerospace applications. Efforts included establishing build parameters, characterizing the alloy, fabricating components, and completing hot-fire testing of complex internal channel-cooled nozzles. These efforts are to address the growing need for large-scale parts using high-performance light-weight materials. Two rocket engine nozzles were fabricated using LP-DED Al6061-RAM2 that included integral cooling channels. The Al6061-RAM2 has completed process development and initial properties were established. This paper provides an overview of the LP-DED process development, material characterization and properties, component manufacturing, supplemental development, and hot-fire testing. Results from hot-fire testing are provided for a lander-class 31kN (7,000lbf)thrust engine using Liquid Oxygen (LOX)/Liquid Hydrogen(LH2) and LOX/Methane(LCH4).
Al6061-RAM2↗
Al6061-RAM2 Development and Hot-Fire Testing using Additive Manufacturing Laser Powder Directed Energy Deposition for Liquid Rocket Engine Channel-Cooled Nozzles
Aluminum 6061-RAM2 is a high-strength aluminum feedstock developed for additive manufacturing (AM)processes. This alloy leverages Reactive Additive Manufacturing (RAM) technology. The RAM aluminum alloys were developed to be weldable—therefore printable—while equaling or exceeding strength properties of high strength wrought aluminum alloys. NASA and industry partners developed Laser Powder Directed Energy Deposition (LP-DED)additive manufacturing of Al6061-RAM2 for use in aerospace applications. Efforts included establishing build parameters, characterizing the alloy, fabricating components, and completing hot-fire testing of complex internal channel-cooled nozzles. These efforts are to address the growing need for large-scale parts using high-performance light-weight materials. Two rocket engine nozzles were fabricated using LP-DED Al6061-RAM2 that included integral cooling channels. The Al6061-RAM2 has completed process development and initial properties were established. This paper provides an overview of the LP-DED process development, material characterization and properties, component manufacturing, supplemental development, and hot-fire testing. Results from hot-fire testing are provided for a lander-class 31kN (7,000lbf) thrust engine using Liquid Oxygen (LOX)/Liquid Hydrogen (LH2) and LOX/Methane (LCH4).
Al6061-RAM2↗
Volumetric direct nuclear pumped laser
A volumetric direct nuclear pumped laser was developed in which the gas is a mixture of He-3 and a minority gas from the group of argon, krypton, xenon, chlorine and fluorine. The mixture of He-3 and the minority gas produces lasing with a minority gas concentration of from 0.01 to 10 percent argon, 1 percent krypton, 0.01 to 5 percent xenon and small concentrations of chlorine or fluorine.
Jalufka, N. W.↗
Development of Large-Scale Thrust Chambers using Laser Powder Directed Energy Deposition
Historical manufacturing methods for liquid propulsion combustion chambers have relied on series of tube-walls or slotted channel walls (subsequently brazed or plated) for regenerative cooling paths. Large-scale additive manufacturing techniques offer strong potential to minimize manufacturing lead times and cost for developing liquid propulsion chambers, while maintaining performance metrics of traditionally manufactured hardware. The benefits expand beyond traditional combustion chambers to lesser considered nuclear thermal propulsion chambers where radiation energizes the singular incoming propellant stream instead of an exothermic chemical reaction. While each subset of liquid propulsion chambers reaps similar benefit, the geometric challenges in each design can vary substantially. This manuscript discusses the challenges of large contraction ratio propulsion chambers, bimetallic liners and closeout jackets, and material selection when considering laser powder directed energy deposition. LP-DED presently offers build volumes unattainable by L-PBF systems, required for large diameter thrust chambers. LP-DED typically has faster deposition time and is capable of overhang angles without support material (due to the ability to tilt the build plate and minimize the actual build angle). These benefits come at the cost of feature resolution. Designers and manufacturers should consider the effects of thick-wall features printed parallel to the primary surface versus perpendicular due to distortion. Thick-wall and thin-wall features printed in the same plane can substantially increase build time. Where large-scale L-PBF overlaps in size, there may be limited benefit in the quantity of powder required for the build due to the low capture rate of LP-DED and a case-by-case examination is required.
LP-DED↗
Size Effects on Laser Powder Bed Fusion and Laser Powder Directed Energy Deposition GRCop-42 Alloy
Additive manufacturing (AM) plays a significant role in the fabrication of regeneratively cooled rocket engine combustion chambers, where internal channels are used to transport high pressure propellants to keep the engine from overheating. Cooling channels are designed with thin walls between the cooling and combustion sides, experiencing high thermal and mechanical stresses from large temperature gradients and internal pressures. Hence, selecting materials suited for this environment and maintaining a high-quality processing for this critical application is of utmost importance. GRCop-alloys (Cu-Cr-Nb) were developed as an ideal material for combustion chambers due to its high conductivity and high strength at temperature, being employed as a structural member for the hotwall with excellent heat transfer capabilities. GRCop-42 (Cu, 4 at% Cr, 2 at% Nb) has significantly matured using the Laser Powder Bed Fusion (L-PBF) process through microstructure, mechanical and thermophysical properties and evaluations using hot-fire testing. Additionally, Laser Powder Directed Energy Deposition (LP-DED) has demonstrated successful deposition and geometry samples using GRCop-42. While the maturation in properties has focused on bulk material properties from standard test specimens, these cannot be extrapolated to be used in thin walls, as different features (i.e., microstructure, porosity, and surface texture) have a greater effect on thin walls, especially on AM structures built using L-PBF and LP-DED. This presentation provides an overview of the effects introduced by reducing the thickness on the fabrication, microstructure, surface metrology and subsequent mechanical properties of GRCop-42 using L-PBF and LP-DED as well as future work planned for this research.
Gabriel Demeneghi↗
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.↗
50 Mbps free space direct detection laser diode optical communication system with Q = 4 PPM signaling
A 50 Mbps direct detection optical communication system for use in an intersatellite link was constructed with an AlGaAs laser diode transmitter and a silicon avalanche photodiode photodetector. The system used a Q = 4 PPM format. The receiver consisted of a maximum likelihood PPM detector and a timing recovery subsystem. The PPM slot clock was recovered at the receiver by using a transition detector followed by a PLL. The PPM word clock was recovered by using a second PLL whose input was derived from the presence of back-to-back PPM pulses contained in the received random PPM pulse sequences. The system achieved a bit error rate of 0.000001 at less than 50 detected signal photons/information bit. The receiver was capable of acquiring and maintaining slot and word synchronization for received signal levels greater than 20 photons/information bit, at which the receiver bit error rate was about 0.01.
Sun, Xiaoli↗
Laser beam directed at the lunar retro- reflector array - Observations of the first returns.
Lunar laser beam retroreflection observations, showing agreement with predicted ephemeris and signal strength
Carrion, W.↗
Advancing Additively Manufactured Al 6061 RAM2 using Laser Powder Directed Energy Deposition
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Additive Manufacturing↗