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DOE OSTI2023

Data-Driven Optimization of the Processing Window for 316H Components Fabricated Using Laser Powder Bed Fusion

The Advanced Materials and Manufacturing Technologies Program is focused on accelerating the development and deployment of advanced materials and components fabricated via additive manufacturing with a specific focus on laser powder bed fusion (LPBF). As an initial case study, the program has selected 316H stainless steel (SS) as an initial material around which to develop a code case development strategy. This strategy involves two parallel approaches: (1) an equivalency approach whereby round-robin testing across multiple collaborating laboratories demonstrates repeatability in processing and direct comparisons with conventional wrought 316H material and (2) a revolutionary approach to code qualification combining in situ data collection and high-fidelity modeling to capture, predict, and bound the performance of LPBF 316HSS components. As part of this campaign, this work package has initiated an extensive process optimization campaign across three laboratories, each printing variations of LPBF 316HSS using three different LPBF units (Concept Laser, EOS, and Renishaw). In FY23, ORNL has focused on unique experimental designs spanning wide ranges in energy inputs and turning knobs such as scan speed, laser power, hatch spacing, layer thickness, spot size, scan rotation, and more. On the Concept Laser M2, 72 different combinations of processing variables were investigated with duplicate samples and different powder compositions. In total, 252 samples were printed with combined in situ sensing data. A parallel design of experiments was conducted on the Renishaw AM400 with an additional 390 printed specimens for analysis. All 642 miniature specimens, each with unique features included in each print to capture geometry-related heterogeneity, were subjected to high-throughput x-ray computed tomography (XCT) analysis to enable the downselection of specific processing parameters of interest. Then, using electrical discharge machining (EDM), miniature tensile specimens were extracted for mechanical testing and microscopy investigations. From the analysis performed in FY23, it was found that powder composition drastically affects the resulting microstructure and mechanical performance of 316SS. Specifically, changing from 316L to 316HSS powder results in a wide range of grain sizes with varying degrees of preferred grain orientation, which increases as a function of energy density. It was also found that due to stored heat in thin fin–type features, large microstructural differences can be seen within one part printed with one set of processing parameters. These variations in microstructure features, including grain size, the nanoscale dislocation structure, and grain texture, will all affect the irradiation performance and high-temperature mechanical performance of LPBF 316HSS parts. Two sets of concept laser processing parameters, spanning both refined and columnar grain structures, were scaled to print larger 316H builds for campaign testing (high-temperature creep and irradiation). In addition, at least two optimized processing parameter sets were identified for the Renishaw AM400 for round-robin testing in FY24 with Argonne National Laboratory. Future work includes printing samples using identical parameters identified by partner institutions, providing material for corrosion and high-temperature mechanical testing, and continuing evaluations of heterogeneity in larger printed parts.

36 MATERIALS SCIENCE↗

NASA NTRS1966

Parametric analysis of microwave and laser systems for communication and tracking Quarterly report, 6 Jun. - 6 Sep. 1966

Parametric analysis of microwave and laser systems for space communication and tracking

SPACE COMMUNICATION↗

NASA NTRS1990

New Space Domain Processing Technique for Pulsed Laser Velocimetry

A new and fast data processing technique for pulsed-laser-velocimetry data is described. A simplified cross correlation algorithm was developed which uses the time history information of the recorded particle images. It is shown that, the use of the particle time history information (which can be obtained using an electronic camera to record the particle exposures) facilitates high speed processing and unambiguous velocity vector information. It was found that a complex convection vortex flow can be recorded and completely processed in less than 2 min on a personal computer, producing a two-dimensional map of the flow field containing over 300 velocity vectors.

Wernet, Mark P.↗

NASA NTRS1992

Active figure maintenance control using an optical truss laser metrology system for a space-based far-IR segmented telescope

A two-stage active control approach was developed addressing the figure control problem for a spaceborne FIR telescope, the Precision Segmented Reflectors Focus Moderate Mission Telescope (FMMT). The first active control stage aligns the optical segments based on images; attention is here given to the second stage, active figure maintenance control system, which maintains the alignment of the optical elements between initializations to hold the mirror figure steady while obtaining data and fixes translational and rotational changes of the optical segments induced by long-term thermal drifts of the support structure. Errors are expected to be 10-100 microns at the nodes of the primary backup structure over the course of an orbit. An rms performance of 0.8 microns of wavefront error can be expected during the maintenance function based on specified nominal sensor noises, actuator accuracies, and system environments. A performance of less than 0.3 microns rms can be expected, based on advanced components.

Lau, Kenneth↗

NASA NTRS1998

Multi-Beam Surface Lidar for Lunar and Planetary Mapping

Surface lidar techniques are now being demonstrated in low Earth orbit with a single beam of pulsed laser radiation at 1064 nm that profiles the vertical structure of Earth surface landforms along the nadir track of a spacecraft. In addition, a profiling laser altimeter, called MOLA, is operating in elliptical Martian orbit and returning surface topography data. These instruments form the basis for suggesting an improved lidar instrument that employs multiple beams for extension of sensor capabilities toward the goal of true, 3-dimensional mapping of the Moon or other similar planetary surfaces. In general the lidar waveform acquired with digitization of a laser echo can be used for laser distance measurement (i.e. range-to-the-surface) by time-of-flight measurement and for surface slope and shape measurements by examining the detailed lidar waveform. This is particularly effective when the intended target is the lunar surface or another planetary body free of any atmosphere. The width of the distorted return pulse is a first order measure of the surface incidence angle, a combination of surface slope and laser beam pointing. Assuming an independent and absolute (with respect to inertial space) measurement of laser beam pointing on the spacecraft, it is possible to derive a surface slope with-respect-to the mean planetary surface or its equipotential gravity surface. Higher-order laser pulse distortions can be interpreted in terms of the vertical relief of the surface or reflectivity variations within the area of the laser beam footprint on the surface.

Bufton, Jack L.↗

NASA NTRS2003

Evaluation and Characterization Study of Dual Pulse Laser-Induced Spark (DPLIS) for Rocket Engine Ignition System Application

This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). Laser ignition has been used at MSFC in recent test series to successfully ignite RP1/GOX propellants in a subscale rocket chamber, and other past studies by NASA GRC have demonstrated the use of laser ignition for rocket engines. Despite the progress made in the study of this ignition method, the logistics of depositing laser sparks inside a rocket chamber have prohibited its use. However, recent advances in laser designs, the use of fiber optics, and studies of multi-pulse laser formats3 have renewed the interest of rocket designers in this state-of the-art technology which offers the potential elimination of torch igniter systems and their associated mechanical parts, as well as toxic hypergolic ignition systems. In support of this interest to develop an alternative ignition system that meets the risk-reduction demands of Next Generation Launch Technology (NGLT), characterization studies of a dual pulse laser format for laser-induced spark ignition are underway at MSFC. Results obtained at MSFC indicate that a dual pulse format can produce plasmas that absorb the laser energy as efficiently as a single pulse format, yet provide a longer plasma lifetime. In an experiments with lean H2/air propellants, the dual pulse laser format, containing the same total energy of a single laser pulse, produced a spark that was superior in its ability to provide sustained ignition of fuel-lean H2/air propellants. The results from these experiments are being used to optimize a dual pulse laser format for future subscale rocket chamber tests. Besides the ignition enhancement, the dual pulse technique provides a practical way to distribute and deliver laser light to the combustion chamber, an important consideration given the limitation of peak power that can be delivered through optical fibers. With this knowledge, scientists and engineers at Los Alamos National Laboratory and CFD Research Corporation have designed and fabricated a miniaturized, first-generation optical prototype of a laser ignition system that could be the basis for a laser ignition system for rocket applications. This prototype will be tested at MSFC in future subscale rocket ignition tests.

Osborne, Robin↗

NASA NTRS2010

Testing of Laser Components Subjected to Exposure in Space

Materials International Space Station Experiment (MISSE) missions provide an opportunity for developing space qualifiable materials by studying the response of novel materials when subjected to the synergistic effects of the harsh space environment. MISSE 6 was transported to the international Space Station (ISS) via STS 123 on March 11. 2008. The astronauts successfully attached the passive experiment containers (PEC) to external handrails of the international space station (ISS) and opened up for long term exposure. After more than a year of exposure attached to the station's exterior, the PEC with several hundred material samples returned to the earth with the STS-128 space shuttle crew that was launched on shuttle Discovery from the Kennedy Space Center, Fla., on Aug. 28. Meanwhile, MISSE 7 launch is scheduled to be launched on STS 129 mission. MISSE-7 was launched on Space Shuttle mission STS-129 on Atlantis was launched on November 16, 2009. This paper will briefly review recent efforts on MISSE 6 and MISSE 7 missions at NASA Langley Research Center (LaRC).

Prasad, Narasimha S.↗

NASA NTRS2018

Telescope Development for LISA

A laser interferometer space-based gravitational wave observatory requires an optical telescope to efficiently transfer laser light between pairs of widely-separated sciencecraft. The application is precision interferometric metrology, and therefore requires the telescope to have high optical pathlength stability, and low scattered light performance. We summarize recent activity on the development of a telescope to meet requirements for the LISA mission, including optimization of the optical design, development of a CAD and finite element model, and thinking about how to live with a high level of particulate contamination on the optics and still meet challenging scattered light requirements.

Livas, Jeff↗

NASA NTRS2004

Three dimensional imaging utilizing structured light

This paper describes a method of remote sensing 3-dimensional structure of the proximity utilizing a laser, a holographic grating, and a single regular CCD camera. Basically, the laser beam is split by a holographic grating to form a regular spaced grid of laser beams that are projected into the field of view of a CCD camera.

Chang, Johnny↗

NASA NTRSDate not supplied

Laser-Processed Condensing Heat Exchanger for Space Applications

In sizing a condensing heat exchanger for space life support systems, there is a limit to allowable pressure drop along with a required vapor recuperation rate. This sizing is performed by using known heat transfer and pressure drop correlations in a numerical model. Dimpling the surface of an air-liquid channeled heat exchanger increases the convective heat transfer rate however creates difficulties within the numerical model as the flat plate correlations are no longer accurate. To increase the fidelity of the numerical model used for sizing the heat exchanger Computational Fluid Dynamics (CFD) with an SST k-ω turbulence model was performed on a periodic portion of the heat exchanger. Through CFD modeling a heat flux and pressure drop was measured across the heat exchanger channel, this information was used to create a localized Nusselt number that was incorporated into the numerical model along with a more accurate pressure drop due to the dimpled surface. Additionally, through modeling the heat exchanger after manufacturing and assembly in Computer Aided Drafting (CAD) software there was an increase in the measurement accuracy of geometric features which was incorporated into the numerical model for further increase in fidelity.

heat exchanger↗

NASA NTRSDate not supplied

Early Results from NASA’s Laser Communications Relay Demonstration (LCRD) Experiment Program

The National Aeronautics and Space Administration’s (NASA) Laser Communications Relay Demonstration (LCRD) mission began its two-year Experiment Program in June 2022. This experimental phase includes long-term measurement of the effects of the atmosphere (turbulence, weather) on the performance and availability of lasercom. Furthermore, various future operational scenarios including robotic and exploration missions and various network service configurations are being emulated. In addition to experiments and demonstrations proposed by the LCRD Investigator Team, NASA enables individuals and groups from government agencies, academia, and industry to propose experiments under the LCRD Guest Experimenters Program. This conference paper provides highlights of the early LCRD experiments and a preview of the future experiments, including relaying data to and from the Integrated LCRD Low-Earth Orbit (LEO) User Modem and Amplifier Terminal (ILLUMA-T) on the International Space Station. The LCRD geosynchronous payload includes two laser communications terminals interconnected via an onboard electronic switch, and can relay information between two optical ground stations located in California and Hawaii. LCRD is a joint project involving NASA Goddard Space Flight Center (GSFC), the NASA Jet Propulsion Laboratory (JPL), and Massachusetts Institute of Technology Lincoln Laboratory (MIT LL).

lasercom↗

NASA NTRSDate not supplied

Early Results from NASA’s Laser Communications Relay Demonstration (LCRD) Experiment Program

lasercom↗

NASA NTRS1988

Global measurements of wind fields using the Laser Atmospheric Wind Sounder (LAWS) on the Earth Observing System (EOS)

The technology for measuring global wind fields in space by the Laser Atmospheric Wind Sounder (LAWS) to be flown on the Earth Observing System (EOS) is discussed. Studies initiated by NASA to determine the feasibility of using Doppler lidar from a platform in space to measure the wind globally have shown the general feasibility of the technique and have identified the technological problems that need to be resolved. Among the lidar systems being evaluated, CO2 coherent detection lidar is given special consideration. A comprehensive research program, the Global Backscatter Experiment, has been established to study global distribution of naturally occurring atmospheric aerosols that provide signal return at the wavelengths used by the techniques under consideration. Wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering the present knowledge of the large-scale atmospheric circulation and climate dynamics, and of global biogeochemical and hydrologic cycles.

Fitzjarrald, Daniel E.↗

NASA NTRS2003

Laser-Based Relative Navigation and Guidance for Space Shuttle Proximity Operations

American manned spacecraft have used visual piloting techniques in the terminal phase of randezvous during the Gemini, Apollo, Skylab, and Space Shuttle programs. In the last several years, space- shuttle astronauts have used the Rendezvous and Proximity Operations Program (RPOP), running; on a laptop computer, as a guidance and navigation aid during proximity operations. By processing measurements to the target satellite taken by a laser sensor, RPOP provides the shuttle crew with a more accurate relative position and velocity than from any other source. The inclusion of guidance algorithms allows RPOP to determine delta-velocities to fly very efficient, repeatable trajectories. This paper will focus on the guidance and navigation algorithms in RPOP, as well as results from simulation and flight. Although developed for shuttle proximity operations, the RPOP algorithms have potential applicability to an automated vehicle.

Laser sensors↗

NASA NTRS2018

Laser Metrology for Ultra-Stable Space-Based Coronographs

Sensing starlight rejected from a coronagraph is essential in stabilizing the telescope pointing and wavefront drift, but performance is degraded for dim stars. Laser Metrology (MET) provides a different, complementary sensing method, one that can be used to measure changes in the alignment of the optics at high bandwidth, independent of the magnitude of the host star. Laser metrology measures changes in the separation of optical fiducial pairs, which can be separated by many meters. The principle of operations is similar to the laser metrology system used in LISA-Pathfinder to measure the in-orbit displacement between two test masses to a precision of ~10 picometers. In closed loop with actuators, MET actively maintains rigid body alignment of the front-end optics, thereby eliminating the dominant source of wavefront drift. In the case of a segmented, active primary mirror, MET provides six degrees of freedom sensing, replacing edge sensors. MET maintains wavefront control even during attitude maneuvers, such as slews between target stars, thereby avoiding the need to repeat time-consuming speckle suppression. These features can significantly improve the performance and observational efficiency of future large-aperture space telescopes equipped with internal coronagraphs. We evaluate MET trusses for various proposed monolithic and segmented space-based coronagraphs and present the performance requirements necessary to maintain contrast drift below 10^-11.

Moore, Dustin↗

NASA NTRS2019

Laser Light Sheet Flow Visualization of the Space Launch System Booster Separation Test

Planar flow visualizations were obtained in a wind tunnel test in the NASA Langley Research Center’s Unitary Plan Wind Tunnel using the laser-light-sheet method. This method uses a laser to illuminate fine particles generated in the wind tunnel to visualize flow structures. The test article was designed to simulate the separation of the two solid rocket boosters (SRBs) from the core stage of the NASA Space Launch System (SLS) at Mach 4 using a scale model. The test was run on of the SLS Block 1B Cargo (27005) configuration and the SLS Block 1B Crew (28005) configuration. Planar flow visualization was obtained only on the crew configuration. Air at pressures up to 1500 psi was used to simulate plumes from the booster separation motors (BSMs) located at the nose, and aft skirt of the two boosters. The facility free stream was seeded with water vapor, which condensed and froze into small ice crystals in the tunnel nozzle expansion. A continuous wave green (532 nm) laser sheet was used to illuminate the ice crystals, and the resulting Mie-scattered light was collected with a camera. The resulting images clearly identify shock waves and other flow features including BSM plume shapes. Measurements were acquired for different BSM pressures and booster separation locations.

Danehy, Paul M.↗

NASA NTRSDate not supplied

Laser Communications Relay Demonstration Optimetrics Experiment

Within this paper, we report on an Optimetrics experiment conducted on the National Aeronautics and Space Administration (NASA) Laser Communication Relay Demonstration (LCRD). The high precision two-way ranging is conducted on the optical communications link between the LCRD space terminal in a geosynchronous orbit and the Optical Ground Station 1 (OGS1) at Table Mountain, California, and is referred to as optimetrics ranging. The receiver to transmitter clock loopback is implemented in the LCRD space modem. A digital dual mixer time difference phase meter (DDMTD) is implemented in the OGS1 ground modem. The round-trip time is measured with the DDMTD by counting the frame and data clock ticks between transmitter and receiver frame synchronization markers for coarse range, and the relative phase of the transmit and receive clock for high precision range. This approach provides coverage for all potential ranges with no ranging ambiguity. The flight modem FPGA code was modified for frame and data clock loopback and the OGS1 FPGA code was modified for the DDMTD phase meter implementation. The experiment team conducted a 36-hour continuous ranging measurement. Preliminary two-way optimetrics ranging data show a noise floor of 3cm (rms). Based on our theoretical noise analysis and ground tests with spare flight modems, we expected one order of magnitude improvement on ranging precision. We are conducting detailed post data processing to identify the differences to further reduce the noise level and formulating an improved implementation approach for future missions. For reference and comparison, traditional Radio Frequency (RF) ranging between LCRD and OGS1 was conducted at the same time and indicates a ranging noise floor of 30cm(rms). Other telemetry and relevant environmental parameters such as weather and atmosphere temperature were also collected for offline data processing. The high precision ranging and range rate measurements from the laser communications data link clock and clock phase are performed simultaneously with continuous optical communication. No extra hardware added to existing system. This high precision optimetrics measurement implementation provides alternative ranging and range rate measurements for orbit determination (OD) and flight dynamics calculations with higher precision. We see significant improvement on OD for navigation upon implementation in future optical communication systems.

Rafael Garcia↗

NASA NTRS1974

Lunar laser ranging data deposited in the National Space Science Data Center: Filtered Observations for July through December 1972 and unfiltered photon dections for January through July 1973

The data acquired by the lunar laser ranging experiment are described for the six months period ending 31 December, 1972. The data are contained on two files of a binary tape written in card image format, using a CDC 6400/6600 computer. Photon detections, and unfiltered photon stops are included.

Mulholland, J. D.↗