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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Progress in developing laser based post irradiation examination infrastructure

To be able to understand the performance of reactor fuels and materials, irradiated materials must be characterized effectively and efficiently in high rad environments. This characterization work is performed remotely and in environments generally hostile to instrumentation. Laser based characterization techniques provide the ability to operate remotely and robustly in a hot-cell environment. Laser based instrumentation also can provide high spatial resolution suitable for scanning and imaging large areas. The INL is currently developing three laser based Post Irradiation Examination (PIE) stations for the Hot Fuel Examination Facility (HFEF) at the INL. These laser based systems will characterize irradiated materials and fuels. The characterization systems are the following: -) laser shock, -) laser based ultrasonic C-scan system and -) gas assay, sample and recharge system (GASR, up-grade to an existing system). The laser shock technique will characterize material properties and failure loads/mechanisms in various materials such as Light Water Reactor (LWR) fuel, plate fuel, and next generation fuel forms in high radiation areas. The laser shock-technique induces large amplitude shock waves to mechanically characterize interfaces such as the fuel-clad bond. As part of the laser shock system, a laser-based ultrasonic C-scan system will be used to detect and characterize de bonding caused by the application of the laser shock as well as performing classical non-destructive evaluation testing and imaging functions such as microstructure characterization, flaw detection and dimensional metrology. A spectroscopy capability can be added later as the salient components to perform Light Induced Breakdown Spectroscopy will be in place. Additional fiber ports in the feed-through will also enable future spectroscopic techniques to be efficiently installed and operated. The purpose of the GASR is to measure the pressure/volume of the plenum of an irradiated fuel element/capsule and obtain fission gas samples for analysis. The study of pressure and volume in the plenum of an irradiated fuel element/capsule and the analysis of fission gases released is important to understanding the performance of reactor fuels and materials. The main function of the laser in this application is to puncture the fuel rod or plate to allow the fission gas to escape and if necessary to weld the hole close. This system may also be used to measure the pressure/volume of other components (such as control blades) and obtain gas samples from these components for analysis. The GASR upgrade will match the functionality of the current system and provide these important functions on fuels made from current and future engineered materials. The GASR station will also have the inherent capability to perform cutting welding and joining functions within a hot-cell. The extra fiber ports built into the hot cell feed-through will also enable the efficient installation of future laser processing work benches. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS2011

Noncontacting Laser Inspection System for Dimensional Profiling of Space Application Thermal Barriers

A noncontacting, two-dimensional (2-D) laser inspection system has been designed and implemented to dimensionally profile thermal barriers being developed for space vehicle applications. In a vehicle as-installed state, thermal barriers are commonly compressed between load sensitive thermal protection system (TPS) panels to prevent hot gas ingestion through the panel interface during flight. Loads required to compress the thermal barriers are functions of their construction, as well as their dimensional characteristics relative to the gaps in which they are installed. Excessive loads during a mission could damage surrounding TPS panels and have catastrophic consequences. As such, accurate dimensional profiling of thermal barriers prior to use is important. Due to the compliant nature of the thermal barriers, traditional contact measurement techniques (e.g., calipers and micrometers) are subjective and introduce significant error and variability into collected dimensional data. Implementation of a laser inspection system significantly enhanced the method by which thermal barriers are dimensionally profiled, and improved the accuracy and repeatability of collected data. A statistical design of experiments study comparing laser inspection and manual caliper measurement techniques verified these findings.

Taylor, Shawn C.↗
DOE OSTI2022

Applicability of semiclassical methods for modeling laser-enhanced fusion rates in a realistic setting

In the context of the potential laser-induced enhancement to the rates of DHe 3 and DT fusion, we discuss the frequently-used Wentzel-Kramers-Brillouin (WKB) method and the imaginary-time method (ITM). For static external electric fields, we find that these methods predict significant enhancement to the fusion cross section for electric-field strengths > 10 14 V/m, especially at low values (≈ keV) for the enter-of-mass (CoM) energy. When considering dynamic electric fields, this enhancement can be amplified by considering increased photon frequencies. However, we also pro- vide a review of the region of laser-parameter phase space where these semiclassical methods are applicable. Here, we conclude that this allowable region decreases for higher photon frequencies in con-junction with lower values for the electric-field strength, motivating the need for future experiments to test the predictions of these methods and their ranges of validity.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1998

Evaluation of Manganese Doped Ca5(PO4)3F as a Near Infrared (1-2 microns) Solid-State Laser Material

Tunable solid-state lasers are of enormous interest for applications including fundamental spectroscopy, remote sensing of the earth atmosphere, medical surgery, and optical communications. Efficient and widely tunable lasers have been developed for the 800-1100 nm region based on transition metal doped insulators like e.g. Ti:Sapphire. The development of transition metal lasers operating at longer wavelength, however, has been limited by the luminescence efficiency of existing materials. We are currently evaluating Mn doped Ca5(PO4)3F as a new solid-state laser material for the 1-2 micro-m region. Preliminary spectroscopic studies revealed that Mn:Ca5(PO4)3F exhibits an intense near infrared luminescence which extends from 1100-1300 nm. Based on lifetime measurements we estimated the luminescence quantum efficiency to be as high as 90 deg./0 at room temperature. The near infrared luminescence properties of Mn doped Ca5(PO4)3F and its potential for solid-state laser applications will be discussed in detail.

Turner, Matthew↗
DOE OSTI2016

Q-switched Erbium-doped fiber laser at 1600 nm for photoacoustic imaging application

We present a nanosecond Q-switched Erbium-doped fiber (EDF) laser system operating at 1600 nm with a tunable repetition rate from 100 kHz to 1 MHz. A compact fiber coupled, acousto-optic modulator-based EDF ring cavity was used to generate a nanosecond seed laser at 1600 nm, and a double-cladding EDF based power amplifier was applied to achieve the maximum average power of 250 mW. In addition, 12 ns laser pulses with the maximum pulse energy of 2.4 μJ were obtained at 100 kHz. Furthermore, the Stokes shift by Raman scattering over a 25 km long fiber was measured, indicating that the laser can be potentially used to generate the high repetition rate pulses at the 1.7 μm region. Finally, we detected the photoacoustic signal from a human hair at 200 kHz repetition rate with a pulse energy of 1.2 μJ, which demonstrates that a Q-switched Er-doped fiber laser can be a promising light source for the high speed functional photoacoustic imaging.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1993

State-of-the-art satellite laser range modeling for geodetic and oceanographic applications

Significant improvements have been made in the modeling and accuracy of Satellite Laser Range (SLR) data since the launch of LAGEOS in 1976. Some of these include: improved models of the static geopotential, solid-Earth and ocean tides, more advanced atmospheric drag models, and the adoption of the J2000 reference system with improved nutation and precession. Site positioning using SLR systems currently yield approximately 2 cm static and 5 mm/y kinematic descriptions of the geocentric location of these sites. Incorporation of a large set of observations from advanced Satellite Laser Ranging (SLR) tracking systems have directly made major contributions to the gravitational fields and in advancing the state-of-the-art in precision orbit determination. SLR is the baseline tracking system for the altimeter bearing TOPEX/Poseidon and ERS-1 satellites and thus, will play an important role in providing the Conventional Terrestrial Reference Frame for instantaneously locating the geocentric position of the ocean surface over time, in providing an unchanging range standard for altimeter range calibration, and for improving the geoid models to separate gravitational from ocean circulation signals seen in the sea surface. Nevertheless, despite the unprecedented improvements in the accuracy of the models used to support orbit reduction of laser observations, there still remain systematic unmodeled effects which limit the full exploitation of modern SLR data.

Klosko, Steve M.↗
NASA NTRS1989

Laser power transmission concepts for Martian applications

Long-term, highly reliable, flexible power will be required to support many diverse activities on Mars and for rapid development of the Mars environment. The potential of laser power transmission for supporting science, materials processing, transportation, and human habitats is discussed. Some advantageous locations for laser power stations in Mars orbit are developed.

De Young, R. J.↗
DOE OSTI2016

Light self-focusing in the atmosphere: Thin window model

Ultra-high power (exceeding the self-focusing threshold by more than three orders of magnitude) light beams from ground-based laser systems may find applications in space-debris cleaning. The propagation of such powerful laser beams through the atmosphere reveals many novel interesting features compared to traditional light self-focusing. It is demonstrated here that for the relevant laser parameters, when the thickness of the atmosphere is much shorter than the focusing length (that is, of the orbit scale), the beam transit through the atmosphere in lowest order produces phase distortion only. This means that by using adaptive optics it may be possible to eliminate the impact of self-focusing in the atmosphere on the laser beam. Furthermore, the area of applicability of the proposed “thin window” model is broader than the specific physical problem considered here. For instance, it might find applications in femtosecond laser material processing.

42 ENGINEERING↗
NASA NTRS1989

A long-range laser velocimeter for the National Full-Scale Aerodynamics Complex: New developments and experimental application

A long-range laser velocimeter (LV) developed for remote operation from within the flow fields of the large wind tunnels of the National Full-Scale Aerodynamics Complex is described. Emphasis is placed on recent improvements in optical hardware as well as recent additions to data acquisition and processing techniques. The system has been upgraded from a dual-beam, single-color LV with focal range to 10 m, to a dual-beam, two-color LV with focal range to 20 m. At the new extended measurement range (between 10 and 20 m), signals are photon-resolved, and a photon correlation technique is applied to acquire and process the LV signals. This technique permits recovery of the velocity probability distributions at a particular measurement location from which the mean components of velocity and the corresponding normal stress components of turbulence are obtained. The method used for data reduction is outlined in detail, and a discussion of measurement accuracy is made. To study the performance of the LV and verify the measurement accuracy, laboratory measurements were made in the flow field of a 10 cm-diameter, 30-m/sec axisymmetric jet. A discussion of the requirements and techniques used to seed the flow is made, and boundary-layer surveys of mean velocity and turbulence intensity of the streamwise component and the component normal to the surface are presented.

Reinath, Michael S.↗
DOE OSTI2021

Experimental and calculational investigation of laser-heated additive manufactured foams

Foam materials are starting to find application in laser-heated Hohlraums used to drive inertial confinement fusion implosions. Foams made using additive manufacturing (AM) techniques are now available and may have advantages over traditional chemical (aerogel) foams. Here, we present new experimental data on laser-heated AM foams. Samples of four different types of printed AM foams were heated using a single 527 nm laser beam at the Jupiter Laser Facility. The laser pulse was ∼180 J square pulse with an FWHM of 1.6 ns and a peak intensity of 3–4 × 1014 W/cm2. The foam densities ranged from 12 to 93 mg/cc (all supercritical for 527 nm light). We measured the backscattered light (power and spectrum), the transmitted light, side-on x-ray images, and the Ti K-shell emission that was used to infer the time-integrated temperature. The fraction of backscattered light was 6%–15% of the input laser energy. The pure carbon foam sample had less backscatter than a C8H9O3 foam of similar density, which was consistent with multi-fluid calculations that predicted less ion heating for the C8H9O3 foam. The level of backscatter and the thermal front speeds for the AM foams were similar to values measured for stochastic (aerogel) foams under similar conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2017

On angiography with a Thomson laser-electron X-ray generator

We consider a possibility of application of laser-electron X-ray generators for diagnosing the vessel status of internal organs. It is shown that modern lasers and linear accelerators can be used for the development of angiographic instruments of a new type with an increased spatial and temporal resolution while maintaining or reducing the radiation load on the patient and medical staff. Such improvements in diagnostic and ambient factors cannot be achieved with the use of X-ray tubes. All particular estimates and calculations have been performed for a contrast agent based on iodine compounds. (paper)

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1992

Evaluation of OH laser-induced fluorescence techniques for supersonic combustion diagnostics

The limitations on application of dye laser and narrowband tunable KrF excimer laser systems to planar OH fluorescence measurements in supersonic combustion test facilities are examined. Included in the analysis are effects of collisional quenching, beam absorption, fluorescence trapping, and signal strengths on achievable measurement accuracy using several excitation and detection options for either of the two laser systems. Dye-based laser systems are found to be the method of choice for imaging OH concentrations less than 10 exp 15 per cu cm, while the KrF based systems provide significant reduction in measurement ambiguity for concentrations in excess of 10 exp 15 per cu cm.

Quagliaroli, T. M.↗
DOE OSTI2016

Laser sintering of a TiO{sub 2} nanoporous film on a flexible substrate for application in solar cells

The selective laser sintering of TiO{sub 2}-film nanoparticles on a plastic conductive substrate is considered for application in flexible dye-sensitized solar cells. It is shown that the absorbed energy of the laser radiation during laser sintering promotes electrical-contact formation between TiO{sub 2} nanoparticles without damaging the plastic conductive substrate. The choice of a near-infrared laser radiation (wavelength of 1064 nm) provides an efficient laser-sintering process. The laser-sintering method promotes a decrease in recombination losses in the TiO{sub 2} film and an improvement in the charge-collection efficiency, which can result in an increase in the efficiency of such solar cells. Furthermore, the efficient-laser sintering method has a great potential for application in the roll-to-roll technology of the fabrication of high-efficiency flexible solar cells.

36 MATERIALS SCIENCE↗
NASA NTRS1992

Laser-beam power for lunar and space applications

Photovoltaic properties of GaAlAs/GaAs heteroface converters were measured using a 0.81-micron diode laser. Results indicate that the converters under consideration are promising devices for converting diode-laser radiation to electricity. Conversion efficiency as high as 45 percent has been obtained using GaAs devices, while Si converters of the SSF type give efficiencies up to 34.2 percent.

Walker, Gilbert H.↗
DOE OSTI2022

High-Efficiency Quantum Dot Lasers as Comb Sources for DWDM Applications

The trend of data center transceivers is to increase bandwidth while simultaneously decreasing their size, power consumption, and cost. While data center links have previously relied on vertical-cavity surface-emitting lasers (VCSELs) or in-plane lasers using coarse wavelength division multiplexing (WDM) to encode data, recently, dense WDM (DWDM) has moved to the forefront for next-generation links. Several approaches exist as light sources for DWDM links; DFB arrays, nonlinear microcombs, and semiconductor mode-locked lasers (MLLs). This paper focuses on quantum dot MLLs (QDMLLs), which currently offer the best efficiency, simplicity, and size. The efficiency of optical combs generated by QDMLLs is analyzed in depth in this study.

Dumont, Mario (ORCID:000000023956612X)↗
DOE OSTI2026

Characterization and automated optimization of laser-driven proton beams from converging liquid sheet jet targets

Compact, stable, and versatile laser-driven ion sources hold great promise for applications ranging from medicine to materials science and fundamental physics. While single-shot sources have demonstrated favorable beam properties, including the peak fluxes necessary for several applications, high-repetition-rate operation will be necessary to generate and sustain the high average flux needed for many of the most exciting applications of laser-driven ion sources. Further, to navigate through the high-dimensional space of laser and target parameters toward experimental optima, it is essential to develop ion acceleration platforms compatible with machine learning techniques and capable of autonomous real-time optimization. Here, we present a multi-Hz ion acceleration platform employing a liquid sheet jet target. We characterize the laser-plasma interaction and the laser-driven proton beam across a variety of key parameters governing the interaction using an extensive suite of online diagnostics. We also demonstrate real-time, closed-loop optimization of the ion beam maximum energy by tuning the laser wave front using a Bayesian optimization scheme. This approach increased the maximum proton energy by 11% compared to a manually optimized wave front by enhancing the energy concentration within the laser focal spot, demonstrating the potential for closed-loop optimization schemes to tune future ion accelerators for robust high-repetition-rate operation.

Glenn, G. D. [SLAC National Accelerator Laboratory↗
DOE OSTI2025

Electronics Free Laser Sensing Technology for Minerals and Technology Elements

This presentation presents an electronics free laser sensing technique and its ongoing and potential applications. A laser-based technique, popularly known as laser-induced breakdown spectroscopy has been prototyped for the determination of high-tech elements including rare earth elements and other elements in solid as well as aqueous sources. All optical unit without any electronics has been designed in such a way that it can be installed in the source environment and connected to other required components for controlling and data acquisition from the workstation. Measurement methods and results obtained for selected elemental species and overall performance of the developed prototype will be presented.

HCM Sensor↗