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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Reconstruction of the BNB and NuMI Neutrino Bunch Structure with ICARUS

ICARUS serves as the Far Detector of the Short Baseline Neutrino (SBN) program at Fermilab, sitting on-axis on the Booster Neutrino Beam (BNB) and 6$^\circ$ off-axis from the Neutrinos at the Main Injector (NuMI) beam. Neutrinos from both beams inherit the timing sub-structure of their parent proton spills, which is in turn derived from either the Booster's or the Main Injector's synchrotron acceleration. Since neutrino propagation introduces only a constant offset, their timing structure is preserved as they travel. Identifying this structure in data represents a powerful tool for selecting neutrino events and searching for physics beyond the Standard Model (BSM). This poster presents the preliminary reconstruction of the BNB and NuMI neutrino bunch structure with ICARUS data, exploiting only the precise timing of ICARUS optical readout system to both locate and assign a time to each interaction.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Reconstruction of the BNB and NuMI Neutrino Bunch Structure with ICARUS

ICARUS serves as the Far Detector of the Short Baseline Neutrino (SBN) program at Fermilab, sitting on-axis on the Booster Neutrino Beam (BNB) and 6$^\circ$ off-axis from the Neutrinos at the Main Injector (NuMI) beam. Neutrinos from both beams inherit the timing sub-structure of their parent proton spills, which is in turn derived from either the Booster's or the Main Injector's synchrotron acceleration. Since neutrino propagation introduces only a constant offset, their timing structure is preserved as they travel. Identifying this structure in data represents a powerful tool for selecting neutrino events and searching for physics beyond the Standard Model (BSM). This poster presents the preliminary reconstruction of the BNB and NuMI neutrino bunch structure with ICARUS data, exploiting only the precise timing of ICARUS optical readout system to both locate and assign a time to each interaction.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Novel Concepts for High Gradient Acceleration (Final Technical Report)

We have conducted an intensive, pioneering program to demonstrate novel concepts for achieving high gradient acceleration at frequencies from the conventional microwave bands up to the millimeter wave /THz bands. High gradient accelerators hold the promise of smaller and less costly accelerators for applications ranging from the largest scale accelerators used for discovery science down to the smallest accelerators used for industrial, homeland security and medical applications. The research consisted of two major research thrusts: 1.) Structure-based wakefield accelerator (SWFA) research in collaboration with the Argonne Wakefield Accelerator research group and 2.) Millimeter Wave / THz high gradient acceleration in collaboration with SLAC. The specific goals of the research program were: Design novel metallic metamaterial structures that increase the beam-wave coupling for the accelerator mode and reduce the effect of high order modes; test novel metamaterial structures to achieve higher output power, > 1 GW at X-Band (11.7 GHz), in test at the Argonne Wakefield Accelerator (AWA); determine the experimental breakdown threshold for nanosecond-scale pulses at X-Band in testing at the AWA; test a 110 GHz accelerator structure with a field emission electron gun, built at SLAC, using pulses from a 1 MW, 110 GHz gyrotron; design, build and test a 110 GHz quasi-optical, resonant-ring pulse compressor to compress microsecond pulses from the 1 MW gyrotron into > 20 MW, 5 ns output pulses for accelerator structure testing. The proposed research program built on our successes in our research program including: Generation of 510 MW, 2.1 ns (FWHM) pulses at 11.7 GHz from a metallic metamaterial structure in test at the Argonne Wakefield Accelerator using a train of eight 65 MeV electron bunches spaced at 1.3 GHz with a total charge of 280 nC. The metamaterial structure consisted of 100 copper unit cells each consisting of a “wagon-wheel” plate and a spacer plate with a total structure length of 0.2 m. The 510 MW pulse generated an on-axis wakefield of 130 MV/m that could be used to accelerate a trailing witness bunch. Demonstration of coupling of an unprecedented rf power level of 575kW into a 110 GHz accelerator structure using a quasi-optical setup. The standing structure consisted of a central copper cavity located between two matching cavities fed by a TM01 mode. The 6 ns input pulses were sliced from 3 microsecond pulses from the gyrotron using a laser-driven silicon switch. We obtained an unprecedented high gradient up to 230MV/m corresponding to a peak surface electric field of more than 520 MV/m.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Sensitive neutron transverse polarization analysis using a 3 He spin filter

Here we report an experimental implementation for neutron transverse polarization analysis that is capable of detecting a small angular change ($\ll$10 –3 rad) in neutron spin orientation. This approach is demonstrated for monochromatic beams, and we show that it could be extended to polychromatic neutron beams. Our approach employs a 3 He spin filter inside a solenoid with an analyzing direction perpendicular to the incident neutron polarization direction. The method was tested with polarized neutron beams and a spin rotator placed inside a μ -metal shield just upstream of the analyzer. No cryogenic superconducting shields or additional neutron spin manipulations are needed. With a counting detector, we experimentally show that the angular resolution δ θ = 1 / ( P n A N ) rad is only determined by the counting statistics for the total counts N and the product of the neutron polarization P n and the analyzing power A . With a high-flux neutron beam, 10 –6 rad angular sensitivity is feasible within a day. This simple, classical-quantum-limited transverse polarization analysis scheme may reduce the overall complexity of experimental implementation for applications requiring sensitive neutron polarimetry and improve the precision in fundamental science studies and polarized neutron imaging.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Nano-laminography with a transmission X-ray microscope

Nano-laminography combines the penetrating power of hard X-rays with a tilted rotational geometry to deliver high-resolution, three-dimensional images of laterally extended, flat specimens that are otherwise incompatible with, or difficult to image using, conventional nano-tomography. In this work, we demonstrate a full-field, X-ray nano-laminography system implemented with the transmission X-ray microscope at beamline 32-ID of the upgraded Advanced Photon Source at Argonne National Laboratory, USA. By rotating the sample around an axis inclined by 20° to the incident beam, the technique minimizes the long optical path lengths that would otherwise generate excessive artifacts when planar samples are imaged edge-on. The efficiency of the technique is demonstrated with 50 nm spatial resolution and minute-scale temporal resolution 3D imaging of a planar integrated circuit sample and targeted imaging of an individual particle within a powder sample, where mounting procedures are typically challenging in regular nano-tomography. The sample mounting strategy, data acquisition, and reconstruction method will also be discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

ORBITAL ANGULAR MOMENTUM BEAMS RESEARCH USING A FREE-ELECTRON LASER OSCILLATOR

Orbital angular momentum (OAM) photon beams are excellent tools for non-contact optical manipulation of mat- ter in a broad photon energy range. A free-electron laser (FEL) oscillator is well-suited for studying OAM beams with various features including a wide spectral coverage, wavelength tunability, two-color lasing, polarization control, etc. Here, we report the first experimental demonstration of superposed OAM beams from an oscillator FEL. Lasing at around 458 nm, we have generated superposed OAM beams up to the fourth order as a superposition of two pure OAM modes with opposite helicities. These generated beams have a good beam quality, a high degree of circular polarization, and high power. Using external rf modulation with frequen- cies from 1 to 30 Hz, we also developed a pulsed mode operation of the OAM beams with a highly reproducible temporal structure. FEL operation showcased in this work can be extended to higher photon energies, e.g. using a future x-ray FEL oscillator. The operation of such an OAM FEL also paves the way for the generation of OAM gamma-ray beams via Compton scattering.

Liu, P.↗
DOE OSTI2022

Scattering-type Scanning Near-Field Optical Microscopy of Polymer-Coated Gold Nanoparticles

Scattering-type scanning near-field optical microscopy (s-SNOM) has emerged over the past years as a powerful characterization tool that can probe important properties of advanced materials and biological samples in a label-free manner, with spatial resolutions lying in the nanoscale realm. In this work, we explore such usefulness in relationship with an interesting class of materials: polymer-coated gold nanoparticles (NPs). As thoroughly discussed in recent works, the interplay between the Au core and the polymeric shell has been found to be important in many applications devoted to biomedicine. We investigate bare Au NPs next to polystyrenesulfonate (PSS) and poly(diallyldimethylammonium chloride) (PDDA) coated ones under 532 nm laser excitation, an wavelength matching the surface plasmon band of the custom-synthesized nanoparticles. We observe consistent s-SNOM phase signals in the case of bare and shallow-coated Au NPs, whereas for thicker shell instances, these signals fade. For all investigated samples, the s-SNOM amplitude signals were found to be very weak, which may be related to reduced scattering efficiency due to absorption of the incident beam. We consider these observations important, as they may facilitate studies and applications in nanomedicine and nanotechnology where the precise positioning of polymer-coated Au NPs with nanoscale resolution is needed besides their dielectric function and related intrinsic optical properties, which are also quantitatively available with s-SNOM.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Beam dynamics in a storage ring with a free-electron laser

In this paper, we study the dynamics of the electron beam in a diffraction limited storage ring with a high-gain free-electron laser. We present in detail the design, including lattice, dynamic aperture, intrabeam scattering, and coherent synchrotron radiation. The simulation of the electron storage ring combined with the free-electron laser is carried out until the electron beam reaches its equilibrium. We find that the initial exponential radiation power is reduced approximately to linear with respect to the undulator length due to the large increase of the energy spread from the free-electron laser.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Four-dimensional dynamics of multirotational transition stimulated rotational Raman scattering in air

Stimulated rotational Raman scattering in air is a powerful parasitic process that degrades high intensity laser beams and pulses propagated over significant distances. Conversely, it is used beneficially in the context of Raman lasers. Through this inelastic scattering process, laser photons are converted to higher (anti-Stokes) or lower (Stokes) energies, according to rotational mode transitions in nitrogen and oxygen diatomic molecules. The full wave-mixing problem involves numerous frequencies, and it is consistently assumed that only one rotational mode contributes to the conversion process. We instead present a dynamic 4D multirotational model that is implemented in a parallelized manner within the Virtual Beamline++ optical modeling package allowing high-resolution 4D studies. We highlight the effect that spontaneous emission plays in large and small beam-width setups, even in the highly saturating regime. The weaker transition modes play a large role in the persistent dynamics and can lead to complex spatiotemporal coupling through nonlinear competition of the modes. We highlight how and why these weaker modes persist, how the size and shape of speckle patterns depends highly on the initial beam profile, and how weaker modes can transiently become stronger as a result of such competition.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Measurement of the QE Map

113 MHz SRF gun utilized CsK 2 Sb and Na 2 KSb cathodes, which were irradiated with a pulsed green laser with a wavelength of 0.53 microns. The drive laser generated 78 kHz pulses with an acousto-optic modulator selecting the desired number of pulses reaching the cathode. The operator can select the aperture size, defining the laser spot diameter on the cathode, and the power level, which is controlled by a rotating polarizer. The laser power reaching the cathode can be measured with a meter based on a photodiode. The quantum efficiency (QE) of a photocathode serves as a primary indicator of its state. Small QE renders the cathode unusable when the desired bunch charge cannot be achieved. Strong variations in the quantum efficiency on the cathode surface might lead to the growth of the beam emittance due to the space charge effects. We have created a routine to measure the distribution of the QE on the cathode. The operator selects the aperture size, the central spot location, and the scan ranges for both planes. The scan starts from the central spots and proceeds along a spiral-like trajectory, making N rounds. The number of rounds can be chosen, and the total number of measured points is (2N+1) 2 . The laser spot movement is shown in Fig. 1.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Anisotropic strain relaxation-induced directional ultrafast carrier dynamics in RuO 2 films

Ultrafast light-matter interactions inspire potential functionalities in picosecond optoelectronic applications. However, achieving directional carrier dynamics in metals remains challenging due to strong carrier scattering within a multiband environment, typically expected for isotropic carrier relaxation. In this study, we demonstrate epitaxial RuO 2 /TiO 2 (110) heterostructures grown by hybrid molecular beam epitaxy to engineer polarization selectivity of ultrafast light-matter interactions via anisotropic strain engineering. Combining spectroscopic ellipsometry, x-ray absorption spectroscopy, and optical pump-probe spectroscopy, we revealed the strong anisotropic transient optoelectronic response at an excitation energy of 1.58 eV in strain-engineered RuO 2 /TiO 2 (110) heterostructures along both in-plane [001] and [1$\bar1$0] crystallographic directions. Theoretical analysis identifies strain-induced modifications in band nesting as the underlying mechanism for enhanced anisotropic carrier relaxation observed at this excitation energy. These findings establish epitaxial strain engineering as a powerful tool for tuning anisotropic optoelectronic responses with near-infrared excitations in metallic systems, paving the way for next-generation polarization-sensitive ultrafast optoelectronic devices.

Science & Technology - Other Topics↗
DOE OSTI2025

Amplification of 10 μm picosecond pulses in a compact optically pumped multiatmosphere CO 2 laser

Picosecond pulses, generated by a commercial mid-IR optical parametric source (∼0.5 ps, 1-5 μJ), have been regeneratively amplified to an energy of ≤2 mJ in a palm-size high-pressure CO 2 amplifier optically pumped by a Q-switched 2.8 μm Cr:Er:YSGG laser. The characteristics of the amplified pulses have been studied as a function of seed wavelength centered around 10.3 or 10.6 μm, and the pressure in the gain medium. The measured amplified pulse length is ∼5 ps. Numerical modeling suggests that pulses as short as ∼0.5 ps with multi-GW peak power can be generated in a mixture of CO 2 isotopes. Robustness of the output of a compact CO 2 regenerative amplifier to the seed and pump fluctuations measured at 3 Hz and a perfect Gaussian beam profile indicates the potential of such laser technology for producing high-power ultrashort long-wave infrared pulses at high repetition rates.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

mystic : software for autonomous discovery and design under uncertainty

Throughout the diverse range of science and engineering applications, there is a growing desire to develop computational methods that can reliably predict the behavior of complex systems. Specifically, there is a strategic need for tools that can robustly forecast the behavior of complex physical systems, where data may be high-dimensional, noisy, or sparse, and models of the system may be time-dependent or include uncertainty. We use mystic to build tools that leverage statistical learning, physics-informed learning, and active learning in the efficient generation of reliably predictive surrogates for complex physical systems. mystic is a robust, proven, open-source optimization and uncertainty quantification toolkit with over a decade of use in the design and optimization of neutron instrumentation, solar-powered drones, and gasguns, and in iterative tuning of models for Raman spectroscopy and elastoplastic materials strength. Recent developments have focused on automated learning of statistically robust surrogates under uncertainty, with applications in materials in extreme environments, nanostructures, materials simulations and strength models, and the failure of shielding under particle radiation. In 2020, McKerns demonstrated active learning of optimally robust surrogates with respect to new simulated data for molecular dynamics simulations of materials mixing in warm dense matter, and is currently applying active learning to the automated steering of particle accelerator beams and the optimal design and control of quantum optical sensor instrumentation.

42 ENGINEERING↗
DOE OSTI2020

Design and Performance of the Solid-State Laser Trigger System for HERMES III

The HERMES III accelerator is an 18-20 MeV linear induction accelerator constructed at Sandia National Laboratories in the late 1980s and which continues operation to this day. As part of recent modernization efforts, the laser triggering system on the accelerator has been replaced with a newly designed solid-state system. This system consists of ten Nd:YAG lasers, each having a nominal output energy of 40-45 mJ at a wavelength of 266 nm. The beam from each laser is split such that it triggers two of the Rimfire gas switches on the accelerator. Compared to the previous laser triggering system, this arrangement makes it possible to more readily tailor the final output pulse shape, and overall reliability for the accelerator's operation with these new lasers has increased. The design of this new laser triggering system is presented in this paper, along with details pertaining to the energy budgeting, optical beam paths, and electrical triggering of the lasers. Initial operational data from the HERMES III accelerator using this new triggering system is also presented.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Fused silica optics damage from downstream intensification on laser-induced damage precursors

Management and control of damage initiation and growth on high-value National Ignition Facility (NIF) optics are critical to its operation. Cone-shaped features are currently being used on the input surfaces to arrest growth of exit surface damage by creating “shadows.” Light refracted from the walls of the cones interferes with the incident beam at the exit surface to create an intensified annulus. Significant exit surface damage was observed at the locations of these annuli. Analysis showed that this damage is consistent with a recently reported new mechanism that degrades damage resistance by dispersing damage precursors over the surface upon exposure to UV laser radiation. This has significant implications for the design and operation of high-energy and power laser systems such as the NIF.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Towards optimal gas cooling with minimal aero-optical distortion for a laser amplifier head

Next-generation lasers combining high-peak-power, ultrashort pulses with high repetition rates have the potential to efficiently deliver the high-average-power outputs required by many emerging technologies and areas of research. This work introduces a three-stage workflow consisting of low- and high-fidelity fluid simulations, in addition to aero-optical analyses. The final goal is to optimize gas cooling within a laser amplifier head while maintaining minimal aero-optical distortions. Low-fidelity RANS simulations are used to obtain mean flow solutions and transition locations. High-fidelity LES simulations, informed by their RANS counterparts, provide solutions containing density fluctuations, which are then passed on to the aero-optical analysis. The aero-optical analysis provides insight into the optical quality of the laser beam passing through the flow found in the LES results.

42 ENGINEERING↗
DOE OSTI2023

FAST Discovery of a Fast Neutral Hydrogen Outflow

Abstract In this letter, we report the discovery of a fast neutral hydrogen outflow in SDSS J145239.38+062738.0, a merging radio galaxy containing an optical type I active galactic nucleus (AGN). This discovery was made through observations conducted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) using redshifted 21 cm absorption. The outflow exhibits a blueshifted velocity likely up to ∼−1000 km s −1 with respect to the systemic velocity of the host galaxy with an absorption strength of ∼−0.6 mJy beam −1 corresponding to an optical depth of 0.002 atv= −500 km s −1 . The mass outflow rate ranges between 2.8 × 10 −2 and 3.6M ⊙ yr −1 , implying an energy outflow rate ranging between 4.2 × 10 39 and 9.7 × 10 40 erg s −1 , assuming 100 K s< 1000 K. Plausible drivers of the outflow include the starbursts, AGN radiation, and radio jet, the last of which is considered the most likely culprit according to the kinematics. By analyzing the properties of the outflow, AGN, and jet, we find that if the Hioutflow is driven by the AGN radiation, the AGN radiation does not seem powerful enough to provide negative feedback, whereas the radio jet shows the potential to provide negative feedback. Our observations contribute another example of a fast outflow detected in neutral hydrogen and demonstrate the capability of FAST in detecting such outflows.

Astronomy & Astrophysics↗
DOE OSTI2022

Distributed Real-time Plume Monitoring for Deep Sea Mineral Extraction​

In the emerging industry of deep-sea mining for minerals and deposits (e.g. polymetallic nodules for nickel, cobalt, copper, and manganese), more data is required to understand the effects of sediment plume generation and predict the distribution of disturbed sediment. There are two main sources of plume generation, the first being at the active mining site where the “collector” directly removes the top layer of the sea floor. The other is the “midwater plume” consisting of unwanted sediment that was collected during extraction that is pumped back into the aphotic zone. The vast majority of plume generation is caused by the collector, causing detrimental and long-lasting impacts on seafloor ecosystems due to the lack of wave activity or strong currents at the sea floor. Therefore, it is crucial to invest in the infrastructure to support the study and constant monitoring over a large area of the sea floor where plume generation is present. Due to the limited number of usable channels and power requirements, current subsea wireless communications technologies are not well suited to instrumenting the large areas of the sea floor needed to monitor plume migration. The scope of this effort is to transition experimental demonstrations of high-bandwidth, full-duplex scalable underwater laser communications to the seafloor in an open ocean environment. Specifically tackling challenges associated with the dynamic nature of the subsea world, including but not limited to, deployment logistics, sustainability, and range. The goal is to enable the internet of underwater things for deep sea industries by broadening the capabilities of subsea communications. By using high-precision laser transmitters, many of the challenges current subsea optical systems face can be circumvented, such as power consumption, interference, and bandwidth limitations. This approach lends itself to wireless interlinking multi-node networks, in series or parallel, facilitating the implementation of a wide array of sensor types. This interlinking allows all the data gathered from the network to be processed through a single hardline uplink to the surface, lowering the complexity required for near real-time data processing. Additionally, the laser control systems produce metadata that can be used to help characterize the water column between the nodes. Combining data from various sensors such as turbidity, temperature, current velocity with metadata such as beam attenuation and deflection can produce a high-resolution model of sea floor conditions around an active mining zone. The resulting near real-time model can be used to optimize location and flow rate of the mining operation to minimize and quantify the environmental impact.

Mons, Ishan↗