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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Generation of collimated vortex gamma-rays from intense Poincaré beam–plasma interaction

We report on numerical calculations in which a multi-petawatt γ-ray beam is generated using a novel configuration based on fully structured light irradiating an overdense plasma waveguide. We analyze how the relativistic laser pulse efficiently confines and accelerates plasma electrons to GeV-scale energies and drives a quasi-static field that induces magneto-bremsstrahlung radiation. Multiphoton Compton scattering of electrons in the intense part of the laser also occurs although the radiated energy-density is comparatively lower. The emitted γ-rays carry orbital angular momentum, are highly collimated, and account for upwards of 15% of the incident field energy in one particular case. A comparison of the laser-to-particle angular momentum and energy transfer efficiencies is made between the cases of irradiation by a circularly polarized Laguerre–Gauss mode and one type of full Poincaré beam, and it is found that the latter yields an order-of-magnitude enhancement. In conclusion, the essential characteristics of the interaction are validated with three-dimensional particle-in-cell simulations that include quantum electrodynamical effects.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

StarDICE III: characterization of the photometric instrument with a collimated beam projector

The measurement of Type Ia supernovae magnitudes provides cosmological distances, which constrain dark energy parameters. Current and upcoming large photometric surveys require improved photometric calibration precision to reduce systematic uncertainties in cosmological constraints. The StarDICE experiment aims to establish accurate broad-band flux references for these surveys, targeting sub-percent precision in magnitude measurements. Achieving this requires precise filter bandpass measurements for both StarDICE and survey instruments with sub-nanometre accuracy. To this end, we developed the Collimated Beam Projector (CBP), an optical device for calibrating the throughput of astronomical telescopes and their filters. The CBP uses a tunable laser source and a reversed telescope to emit a parallel monochromatic light beam, continuously monitored in flux and wavelength. The CBP output flux is measured with a large-area photodiode calibrated relative to a NIST photodiode. Using CBP measurements, we derive the StarDICE telescope throughput and filter transmissions, anchoring them to NIST’s absolute calibration. After analysing systematic uncertainties, we achieved sub-nanometre accuracy for filter central wavelengths, measured filter transmission with ~0.5 per cent precision per 1 nm bin, and detected out-of-band leakages at a relative level of 10 –4 ⁠. Furthermore, we synthesized equivalent transmission for full pupil illumination from four sampled positions in the StarDICE telescope mirror, with ~0.2 nm accuracy for central wavelengths and 7 mmag for broad-band fluxes. This demonstrates our ability to characterize telescope throughput down to the millimagnitude, paving the way for future developments, such as the Rubin-CBP for measuring the LSST at Vera Rubin Observatory, and a portable CBP version for in-situ transmission monitoring.

Calibration↗
DOE OSTI2026

Sagittal collimating diaboloid: a new grazing-incidence mirror surface for higher-throughput resonant inelastic X-ray scattering spectrometers

A major challenge in soft X-ray spectroscopy is the efficient collection of the emitted X-rays by grazing-incidence mirrors. In this energy range, grazing-incidence mirrors are widely used as optics for the collection of light. The small angle of incidence necessarily limits the collection solid angle of soft X-ray spectrometers. We present a new mirror surface, a sagittal collimating diaboloid, that can both collect and focus light from a point source in an aberration-free manner. The usefulness of this optic in increasing throughput is demonstrated with a realistic example design of a moderate-sized (3 m) medium-resolution resonant inelastic X-ray scattering spectrometer.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Accobeam - Acoustic Collimated Beam

Researchers at Los Alamos have developed a collimated acoustic imaging technology for non-destructive characterization of highly attenuating media, such as concrete, rocks, mud, and metal casings. The technology is used to investigate structural defects that could compromise important assets such as well boreholes, building structures and sensitive materials like explosives. Current acoustic methods are often unable to penetrate such materials deeply for more informative analysis, which limits what can be learned about asset structural integrity, crucial information companies require to make investment decisions such as fixing or replacing structures well before assets are completely compromised. ACCObeam provides requisite penetration and high-resolution acoustic imaging with applications in borehole imaging, explosives threat evaluation, and structural health evaluation. This technology will potentially save companies significant money by producing accurate and useful visual analyses to better understand the actual condition of assets in the field and respond accordingly. Los Alamos is searching for a collaboration partner to develop this technology for commercial applications that will lead to licensing opportunities for broad industry deployment.

36 MATERIALS SCIENCE↗