Development testing and application of a three-dimensional laser Doppler velocimeter for the measurement of gas flows
Three-dimensional laser Doppler velocimeter for measuring local mean and fluctuating gas velocities
Fuller, C. E.↗
SEARCH · Engineering Papers
Results for “laser testing”
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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Design of a CO2 laser power control system for a Spacelab microgravity experiment
The surface tension driven convection experiment (STDCE) is a Space Transportation System flight experiment manifested to fly aboard the USML-1 Spacelab mission. A CO2 laser is used to heat a spot on the surface of silicone oil contained inside a test chamber. Several CO2 laser control systems were evaluated and the selected system will be interfaced with the balance of the experimental hardware to constitute a working engineering model. Descriptions and a discussion of these various design approaches are presented.
Wenzler, Carl J.↗
A ruggedness evaluation of procedures for damage threshold testing optical materials
A ruggedness evaluation of approaches to damage threshold testing was performed to determine the influence of three procedural variables on damage threshold data. The differences between the number of test sites evaluated at an applied fluence level (1 site versus 10 sites), the number of laser pulses at each test site (1 pulse versus 200 pulses), and the beam diameter (0.35 mm versus 0.70 mm) were all found to significantly influence the damage threshold data over a 99-percent confidence interval.
Hooker, Matthew W.↗
Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating
Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also provide a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm 2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.
36 MATERIALS SCIENCE↗
Laser Ablation, Absorbance Ratio Spectrometry (LAARS) Assay Performance Study (FY2018 Annual Report)
The International Atomic Energy Agency (IAEA) has a long history of testing and using laser-based technologies for a variety of safeguards applications. Notable laser-based on-site applications include: 3-dimensional laser range (3DLR) instruments, used for facility design information and verification (DIV); laser measurements to verify unique labels and detect signs of tampering; and laser spectroscopy, for non-contact process monitoring. The IAEA is also evaluating analytical laboratory instruments, such as laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for interrogating individual particles to determine uranium isotopic ratios in collected environment samples. Recent laser technology advancements will continue to fuel future IAEA adoption of new and novel laser-based safeguards tools. Pacific Northwest National Laboratory (PNNL) is developing one such tool, called the Laser Ablation, Absorbance Ratio Spectrometry (LAARS) technology, which is designed to provide high-fidelity 235 U/ 238 U isotope ratio measurements to support either on-site enrichment plant or off-site laboratory destructive assay (DA). Analyzing uranium hexafluoride (UF 6 ) DA samples on-site by LAARS could provide early indication of discrepancies with operator declarations during physical inventory verifications, so that such discrepancies could be addressed immediately, rather than after off-site analysis is completed. The IAEA is also seeking on-site DA options, because sample shipping time can be long and evolving restrictions on radioactive/corrosive material shipments may increasingly limit the IAEA’s ability to easily transport UF 6 samples. Routine on-site LAARS analysis could provide timely assay results and reduce the DA sample shipment inventory to just those needed for more definitive determination. A laboratory-based LAARS instrument could also provide rapid, cost-effective prescreening of selected DA samples shipped to the IAEA’s Nuclear Materials Laboratory in Seibersdorf, Austria. PNNL has also developed a complementary UF 6 sampling technology and method, called the Single-Use Destructive Assay (SUDA) sampler to easily collect DA samples that are ideal for on-site analysis by LAARS. Combining the LAARS and SUDA sampler technologies could provide a powerful new on-site DA option for the IAEA.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Further Investigation Into the Use of Laser Surface Preparation of Ti-6Al-4V Alloy for Adhesive Bonding
Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes currently applied to Ti-6Al-4V alloys. Laser ablation imparts both topographical and chemical changes to a surface that can lead to increased bond durability. A laser based process provides an alternative to chemical-immersion, manual abrasion, and grit blast process steps which are expensive, hazardous, environmentally unfriendly, and less precise. In addition, laser ablation is amenable to process automation, which can improve reproducibility to meet quality standards for surface preparation. An update on work involving adhesive property testing, surface characterization, surface stability, and the effect of laser surface treatment on fatigue behavior is presented. Based on the tests conducted, laser surface treatment is a viable replacement for the immersion chemical surface treatment processes. Testing also showed that the fatigue behavior of the Ti-6Al-4V alloy is comparable for surfaces treated with either laser ablation or chemical surface treatment.
Palmieri, Frank L.↗
Direct Laser Impulse (DLI) System Alignment: Requirements Engineering Project
The National Ignition Facility (NIF) is the world’s largest and most energetic laser, and it is comprised of 192 laser beams that must align onto one target for the purpose of learning about Internal Confinement Fusion (ICF) and High Energy Density (HED) physics. A new NIF capability under development is the Direct Laser Impulse (DLI). The DLI capability will provide a test environment where high pulsed laser energy is delivered to a three-dimensional target. Achieving this delivery to target relies on a precision alignment and positioning of the two redirected NIF beams, as shown in Figure 1. When aligned, the two combined beams—with a frequency converted from infrared (IR) to green laser light, at a fluence (energy per unit area) of roughly 20 joules per square centimeter—will be capable of delivering up to 30 kilojoules of direct, unfocused energy to a one cubic foot target. The 40-cm x 40-cm aligned impulse area at the DLI target interaction plane (TIP) is achieved by using a beam path comprised of pickoff and transport mirrors, frequency conversion crystals, optics serving as environmental barriers, and debris shields. A separate aligned diagnostic beam path is also required for impulse to TIP characterization. Final in-situ alignment is required for the two populated diverted NIF beam paths onto the DLI target as well as the diagnostic optical beam path. Existing NIF alignment subsystems do not offer references that meet DLI’s unique demand. The new DLI Red Box, which has been designed to allow for alignment, has been shown to require deviation from the intended configuration and operational use case to obtain adequate functionality. A systems engineering evaluation has identified a solution that meets the stakeholder requirements while optimizing key performance parameters. The solution, referred to in this document as the Red Box “+” Rotated, was determined to be an improved version of the current DLI Red Box. This system offers improved system repeatability and alignment stability while maintaining similar interfaces and decreasing the demand for engineer/operator interaction.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NARC Rayon Replacement Program for the RSRM Nozzle, Phase IV Qualification and Implementation Status
The Space Shuttle NARC Rayon Replacement Program has down-selected Enka rayon as a replacement for the obsolete NARC rayon in the nozzle carbon cloth phenolic (CCP) ablative insulators. Full qualification testing of the Enka rayon-based carbon cloth phenolic is underway, including processing, thmal/structural properties, and hot-fire subscale tests. Required thermal-structural capabilities, together with confidence in erosio/char performance in simulated and subscale hot fire tests such as Wright-Patterson Air Force Base Laser Hardened Materials Evaluation Laboratory testing, NASA-MSFC 24-inch motor tests, NASA-MSFC Solid Fuel Torch - Super Sonic Blast Tube, NASA-MSFC Plasma Torch Test Bed, ATK Thiokol Forty Pound Charge and NASA-MSFC MNASA justified the testing of the new Enka-rayon candidate on full-scale static test motors. The first RSRM full-scale static test motor nozzle, fabricated using the new Enka rayon-based CCP, was successfully demonstrated in June 2004. Two additional static test motors are planned with the new Enka rayon in the next two years along with additional A-basis property characterization. Process variation or "corner-of-the-box" testing together with cured and uncured aging studies are also planned as some of the pre-flight implementation activities with 5-year cured aging studies over-lapping flight hardware fabrication.
Haddock, M. Reed↗
Coating adhesion of a chromate-containing epoxy primer on Al2024-T3 surface processed by laser-interference
In this work, the coating adhesion test results are presented for a primer that was coated on laser-interference structured surfaces of as-received Al2024-T3 specimens, i.e., without employing any polishing, cleaning, or any other surface alteration techniques. All of the laser-interference processing was performed by splitting the primary beam of a Q-switched Nd:YAG pulsed nanosecond laser into two beams and focused them to the same spot. The specimens were spray painted with a chromate-containing epoxy primer, CA7233, compliant to MIL-PRF-23377 Type I Class C2 specification. The adhesion of primer on Al surface with different treatments was assessed using the ASTM D3359 X-cut and cross-hatch tests. It was found that the laser processed specimens meet the performance requirements in the coating adhesion specifications by having a higher or identical ranking for coating adhesion specimens than those prepared with current state-of-the-art chemical conversion or sulfuric acid anodizing. The rastering with either 4 mm/s or 6 mm/s with a laser fluence of 1.78 J/cm2 is recommended to attain acceptable coating adhesion, even higher than that with the anodizing surface treatment.These results indicate that laser-interference shows significant potential as a non-chemical surface preparation technique for these coatings.
36 MATERIALS SCIENCE↗
Monitoring Xenon Capture in a Metal Organic Framework Using Laser-Induced Breakdown Spectroscopy
Molten salt reactor operation will necessitate circulation of a cover gas to remove certain evolved fission products and maintain an inert atmosphere. The cover gas leaving the reactor core is expected to contain both noble and non-noble gases, aerosols, volatile species, tritium, and radionuclides and their daughters. To remove these radioactive gases, it is necessary to develop a robust off-gas system, along with novel sensors to monitor the gas stream and the treatment system performance. In this study, a metal organic framework (MOF) was engineered for the capture of Xe, a major contributor to the off-gas source term. The engineered MOF column was tested with a laser-induced breakdown spectroscopy (LIBS) sensor for noble gas monitoring. The LIBS sensor was used to monitor breakthrough tests with various Xe, Kr, and Ar mixtures to determine the Xe selectivity of the MOF column. This study offers an initial demonstration of the feasibility of monitoring off-gas treatment systems using a LIBS sensor to aid in the development of new capture systems for molten salt reactors.
47 OTHER INSTRUMENTATION↗
High energy lasers as a stability rating device
A very cursory test program was performed to evaluate the feasibility of using a 100W CO2 laser to initiate resonant oscillations in a test combustor. GOX/RP-1 were selected as propellants due to the absorption characteristics of RP-1 and due to test facility capabilities. Very low amplitude oscillations were initiated during laser pulsing that correspond to the first longitudinal mode of the test engine.
Breisacher, Kevin J.↗
An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement
An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight, complex shapes, large structure dimension, large current, and low frequency capabilities are important considerations.
Nguyen, Truong X.↗
Gas-laser behavior in a low-gravity environment
In connection with several experiments proposed for flight on the Space Shuttle, which involve the use of gas lasers, the behavior of a He-Ne laser in a low-gravity environment has been studied theoretically and experimentally in a series of flight tests using a low-gravity-simulation aircraft. No fluctuation in laser output above the noise level of the meter (1 part in 1000 for 1 hr) was observed during the low-gravity portion of the flight tests. The laser output gradually increased by 1.4% during a 1.5-hr test; at no time were rapid variations observed in the laser output. A maximum laser instability of 1 part in 100 was observed during forty low-gravity parabolic maneuvers. The beam remained Gaussian throughout the tests and no lobe patterns were observed.
Owen, R. B.↗
Laser Tracker Utilization Methodology in Measuring Truth Trajectories for INS Testing on 6 Degree of Freedom Table at the Marshall Space Flight Center's Contact Dynamics Simulation Laboratory with Lessons Learned
When performing Inertial Navigation System (INS) testing at the Marshall Space Flight Center's (MSFC) Contact Dynamics Simulation Laboratory (CDSL) early in 2017, a Leica Geosystems AT901 Laser Tracker system (LLT) measured the twist & sway trajectories as generated by the 6 Degree Of Freedom (6DOF) Table in the CDSL. These LLT measured trajectories were used in the INS software model validation effort. Several challenges were identified and overcome during the preparation for the INS testing, as well as numerous lessons learned. These challenges included determining the position and attitude of the LLT with respect to an INS-shared coordinate frame using surveyed monument locations in the CDSL and the accompanying mathematical transformation, accurately measuring the spatial relationship between the INS and a 6DOF tracking probe due to lack of INS visibility from the LLT location, obtaining the data from the LLT during a test, determining how to process the results for comparison with INS data in time and frequency domains, and using a sensitivity analysis of the results to verify the quality of the results. While many of these challenges were identified and overcome before or during testing, a significant lesson on test set-up was not learned until later in the data analysis process. It was found that a combination of trajectory-dependent gimbal locking and environmental noise introduced non-negligible noise in the angular measurements of the LLT that spanned the evaluated frequency spectrum. The lessons learned in this experiment may be useful for others performing INS testing in similar testing facilities.
Leggett, Jared O.↗
Towards Portable Laser Desorption Postionization Mass Spectrometry Utilizing Microchip Laser Pulses
A 355 nm, 1.5 ns, up to 1 kHz microchip laser system has been tested to both yield ablation spots and postionize material within a plasma plume. A 30 µJ pulse energy microchip laser successfully ablated all samples: 6601 aluminum, 316 and 304 stainless steel, and Mo metal. While visible ablation craters were observed on all samples mentioned above, the stainless-steel samples displayed visible color changes in the resolidified iron, indicating ionization with the 355 nm pulses during ablation. Additionally, when used to intercept a plasma plume of Cs 2 CO 3 made with a separate laser system, the microchip laser pulses yielded Cs + emission signal otherwise not observed. With these experiments completed, the microchip laser has been successfully verified for readiness to be integrated into the front end of a mass spectrometer system as the ion source.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Subsonic Jet Noise Reduced With Improved Internal Exhaust Gas Mixers
Aircraft noise pollution is becoming a major environmental concern for the world community. The Federal Aviation Administration (FAA) is responding to this concern by imposing more stringent noise restrictions for aircraft certification then ever before to keep the U.S. industry competitive with the rest of the world. At the NASA Lewis Research Center, attempts are underway to develop noise-reduction technology for newer engines and for retrofitting existing engines so that they are as quiet as (or quieter than) required. Lewis conducted acoustic and Laser Doppler Velocimetry (LDV) tests using Pratt & Whitney's Internal Exhaust Gas Mixers (IEGM). The IEGM's mix the core flow with the fan flow prior to their common exhaust. All tests were conducted in Lewis' Aero-Acoustic Propulsion Laboratory--a semihemispheric dome open to the ambient atmosphere. This was the first time Laser Doppler Velocimetry was used in such a facility at Lewis. Jet exhaust velocity and turbulence and the internal velocity fields were detailed. Far-field acoustics were also measured. Pratt & Whitney provided 1/7th scale model test hardware (a 12-lobe mixer, a 20-lobe mixer, and a splitter) for 1.7 bypass ratio engines, and NASA provided the research engineers, test facility, and test time. The Pratt & Whitney JT8D-200 engine power conditions were used for all tests.
Source record↗
Proposal for Testing and Validation of Vacuum Ultra-Violet Atomic Laser-Induced Fluorescence as a Method to Analyze Carbon Grid Erosion in Ion Thrusters
Previous investigation under award NAG3-25 10 sought to determine the best method of LIF to determine the carbon density in a thruster plume. Initial reports from other groups were ambiguous as to the number of carbon clusters that might be present in the plume of a thruster. Carbon clusters would certainly affect the ability to LIF; if they were the dominant species, then perhaps the LIF method should target clusters. The results of quadrupole mass spectroscopy on sputtered carbon determined that minimal numbers of clusters were sputtered from graphite under impact from keV Krypton. There were some investigations in the keV range by other groups that hinted at clusters, but at the time the proposal was presented to NASA, there was no data from low-energy sputtering available. Thus, the proposal sought to develop a method to characterize the population only of atoms sputtered from a graphite target in a test cell. Most of the ground work had been established by the previous two years of investigation. The proposal covering 2003 sought to develop an anti-Stokes Raman shifting cell to generate VUW light and test this cell on two different laser systems, ArF and YAG- pumped dye. The second goal was to measure the lowest detectable amounts of carbon atoms by 156.1 nm and 165.7 nm LIF. If equipment was functioning properly, it was expected that these goals would be met easily during the timeframe of the proposal, and that is the reason only modest funding was requested. The PI was only funded at half- time by Glenn during the summer months. All other work time was paid for by Whitworth College. The college also funded a student, Charles Shawley, who worked on the project during the spring.
Stevens, Richard↗
Eyes On the Ground: Year 2 Assessment.
The goal of the Eyes On the Ground project is to develop tools to aid IAEA inspectors. Our original vision was to produce a tool that would take three-dimensional measurements of an unknown piece of equipment, construct a semantic representation of the measured object, and then use the resulting data to infer possible explanations of equipment function. We report our tests of a 3-d laser scanner to obtain 3-d point cloud data, and subsequent tests of software to convert the resulting point clouds into primitive geometric objects such as planes and cylinders. These tests successfully identified pipes of moderate diameter and planar surfaces, but also incurred significant noise. We also investigated the IAEA inspector task context, and learned that task constraints may present significant obstacles to using 3-d laser scanners. We further learned that equipment scale and enclosing cases may confound our original goal of equipment diagnosis. Meanwhile, we also surveyed the rapidly evolving field of 3-d measurement technology, and identified alternative sensor modalities that may prove more suitable for inspector use in a safeguards context. We conclude with a detailed discussion of lessons learned and the resulting implications for project goals. Approved for public release; further dissemination unlimited.
47 OTHER INSTRUMENTATION↗