X -band rf driven free electron laser driver with optics linearization
Not Available
43 PARTICLE ACCELERATORS↗
SEARCH · Engineering Papers
Results for “Laser”
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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Interaction physics for the stimulated Brillouin scattering of a laser in laser driven fusion
Energy exchange between pump wave and ion-acoustic wave during the stimulated Brillouin Scattering process in relativistic laser-plasma interactions is studied, including the effect of damping coefficient of electron-ion collision by obeying the energy and momentum conservations. The variations of plasma density and damping coefficient of electron-ion collision change the amplitudes of the interacting wave. The relativistic mass effect modifies the dispersion relations of the interacting waves and consequently, the energy exchange during the stimulated Brillouin Scattering is affected. The collisional damping of electron-ion collision in the plasma is shown to have an important effect on the evolution of the interacting waves. (author)
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
High Temperature Laser Generation of Quantum-Cascade Lasers in the Spectral Region of 8 μm
Abstract—In this paper, we present studies of the characteristics of quantum-cascade lasers with a generation wavelength in the region of 8 μm at high temperatures of up to + 65°C. The characteristic temperatures of the temperature dependences of the threshold current and the differential efficiency are determined. Spectral studies showed the presence of two generation lines with a short wavelength of ~7800 nm and a long-wave wavelength of ~8100 nm. The observed competition between the short-wave and long-wave generation lines leads to a nonmonotonic character of the dependence of the radiation intensity on the pump current.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Determination of Rare Earth Elements in Geological Samples Using Laser-Induced Breakdown Spectroscopy (LIBS) [Determination of Rare Earth Elements in Geological Samples by Laser-Induced Breakdown Spectroscopy (LIBS)]
Laser-induced breakdown spectroscopy (LIBS) was used to detect rare earth elements (REEs) in natural geological samples. Low and high intensity emission lines of Ce, La, Nd, Y, Pr, Sm, Eu, Gd, and Dy were identified in the spectra recorded from the samples to claim the presence of these REEs. Multivariate analysis was executed by developing partial least squares regression (PLS-R) models for the quantification of Ce, La, and Nd. Analysis of unknown samples indicated that the prediction results of these samples were found comparable to those obtained by inductively coupled plasma mass spectrometry analysis. In conclusion, data support that LIBS has potential to quantify REEs in geological minerals/ores.
58 GEOSCIENCES↗
Spectral Linewidth Narrowing and Tunable Two-Color Laser Operation of Two Diode Laser Arrays
We propose and implement a common external cavity to narrow spectral linewidth of two broad-area laser diode arrays (LDAs) and align their center wavelengths. The locked center wavelength of two LDAs can be tuned in the range of {approx}10 nm by tuning the tilted angle of the diffraction grating. The output beams of two LDAs are spatially overlapped through the polarization beam splitter of the common external cavity, and the total output power equals the power of two LDAs. The center wavelength of each LDA can be independently tuned by shifting the corresponding fast-axis collimation lens. As a result, the high-power two-color LDA operation is demonstrated with the tunable wavelength difference of up to 2 nm ({approx}1 THz).
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Nano-indentation and laser-induced damage testing in optical multilayer-dielectric gratings [Nanomechanics and laser-induced damage in optical multilayer dielectric gratings]
Here, we demonstrate how a nanomechanical test can be used to generate metrics to complement laser-induced–damage testing (LIDT) measurements and show that differences in optical performance of the gratings (arising from changes in cleaning process and/or fabrication methods) can be related to their mechanical reliability. Data are presented on LIDT measurements in diffractive gratings of silica deposited on optical multilayers. The nano-indentation response of the diffraction gratings is measured in a new mode that allows for the extraction of a measurable metric characterizing the brittleness of the gratings, as well as their ductility. We show that lower LIDT’s are positively correlated with an increased grating brittleness, and therefore identify a nanomechanical approach to describe LIDT’s. We present extensive numerical simulations of nano-indentation tests and identify different deformation modes including stretching, shear concentration, and bending as precursors to mechanical failure in the nano-indentation test. The effects of geometrical inhomogeneities on enhanced stress generation in these gratings are specifically examined and addressed.
36 MATERIALS SCIENCE↗
w22_laser_radiography - Laser-Based MeV Radiography
This project seeks to develop novel x-ray sources based on high-power short-pulse lasers with unique advantages, including small spot size, flexible configuration, and tailorable spectra. Kinetic plasma simulations using the VPIC particle in cell code will be performed to support the R&D goals of this project. If successful, this effort will allow LANL to deploy flexible, compact x-ray sources for static tomographic radiography and dynamic multi-axis radiography at our firing sites and facilities such as pRad and U1a. The higher resolution, shorter pulse duration, and tunability of our proposed sources will enable new applications in the weapons program and broader scientific community. This effort advances the LANL FY22 Strategic Investment Plan priority of “[r]adiographic tools for dynamic and static imaging with improved spatial and temporal resolution, sensitivity, and dose.”
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Continuous wave laser ground-to-space-to- ground laser experiment.
Continuous wave laser ground-space-ground experiment in conjunction with Explorer XXII SATELLITE tracking
SATELLITE TRACKING↗
A 3.5-Watt Q-Switched 532 nm Nd:YAG Laser Pumped with Fiber-Coupled Diode Lasers
A diode-pumped laser with over 11 W of continuous-wave 1064 nm, and 3.5 W of frequency-doubled average power at 50 kHz pulse repetition frequency, has been developed.
diode-pumped laser↗
Mid-Infrared Interband Cascade Lasers for Free-Space Laser Communication
We have fabricated high-speed Interband Cascade lasers and provided the first experimental evidence that these devices can be directly modulated at a frequency of 3.2 GHz and above.
semiconductor lasers↗
Crystal Growth and Characterization of Epitaxial Layers of Laser and Nonlinear Optical Materials for Thin-Disk and Waveguide laser applications
This paper summarizes the main results we obtained in our laboratories in relation with crystalline layers obtained by liquid phase epitaxial growth of lanthanide doped KLu(WO{sub 4}){sub 2} and Nb:RbTiOPO{sub 4} grown on KLu(WO{sub 4}){sub 2} and RbTiOPO{sub 4} substrates, respectively. Macroscopic defect free epitaxial layers were grown and characterized in terms of their compositional homogeneity, structural stress in the layer/substrate interface and laser and waveguiding performances.
36 MATERIALS SCIENCE↗
Transient Laser-Induced Breakdown of Dielectrics in Ultrarelativistic Laser-Solid Interactions
Not Available
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Pressure dependence of the laser-metal interaction under laser powder bed fusion conditions probed by in situ X-ray imaging
Not Available
36 MATERIALS SCIENCE↗
Laser-Induced Graphene Composites for Printed, Stretchable, and Wearable Electronics
Not provided.
Materials Science↗
Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective
Abstract 316L stainless steel (316L SS) is a flagship material for structural applications in corrosive environments, having been extensively studied for decades for its favorable balance between mechanical and corrosion properties. More recently, 316L SS has also proven to have excellent printability when parts are produced with additive manufacturing techniques, notably laser powder bed fusion (LPBF). Because of the harsh thermo-mechanical cycles experienced during rapid solidification and cooling, LPBF processing tends to generate unique microstructures. Strong heterogeneities can be found inside grains, including trapped elements, nano-inclusions, and a high density of dislocations that form the so-called cellular structure. Interestingly, LPBF 316L SS not only exhibits better mechanical properties than its conventionally processed counterpart, but it also usually offers much higher resistance to pitting in chloride solutions. Unfortunately, the complexity of the LPBF microstructures, in addition to process-induced defects, such as porosity and surface roughness, have slowed progress toward linking specific microstructural features to corrosion susceptibility and complicated the development of calibrated simulations of pitting phenomena. The first part of this article is dedicated to an in-depth review of the microstructures found in LPBF 316L SS and their potential effects on the corrosion properties, with an emphasis on pitting resistance. The second part offers a perspective of some relevant modeling techniques available to simulate the corrosion of LPBF 316L SS, including current challenges that should be overcome.
Voisin, T. (ORCID:0000000287462659)↗
Characterization of the Fe-Co-1.5V soft ferromagnetic alloy processed by Laser Engineered Net Shaping (LENS)
Processing of the low workability Fe-Co-1.5V (Hiperco® equivalent) alloy is demonstrated using the Laser Engineered Net Shaping (LENS) metals additive manufacturing technique. As an innovative and highly localized solidification process, LENS is shown to overcome workability issues that arise during conventional thermomechanical processing, enabling the production of bulk, near net-shape forms of the Fe-Co alloy. Bulk LENS structures appeared to be ductile with no significant macroscopic defects. Atomic ordering was evaluated and significantly reduced in as-built LENS specimens relative to an annealed condition, tailorable through selection of processing parameters. Fine equiaxed grain structures were observed in as-built specimens following solidification, which then evolved toward a highly heterogeneous bimodal grain structure after annealing. The microstructure evolution in Fe-Co is discussed in the context of classical solidification theory and selective grain boundary pinning processes. In conclusion, magnetic properties were also assessed and shown to fall within the extremes of conventionally processed Hiperco® alloys.
36 MATERIALS SCIENCE↗