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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Modeling LANSCE Line D and RI Beamlines in Elegant and Impact-T

This technical report describes models in Elegant and Impact-T of two LANSCE high-energy beamlines: LineD and Ring Injection. These two beamlines transport the 800 MeV H- beam from the exit of the 805 MHz Linac to the entrance of the PSR. Computer models of all LANSCE high-energy beamlines exist in Transport but include a limited model of the space charge forces. A motivation for using Elegant as an optional beam dynamics code is that the existing model of the PSR is in Elegant, therefore enabling the modeling of the full beam injection scheme. Also, Elegant is a modern code being used by a large accelerator physics community which makes the calculation results more reliable. The drawback is that Elegant has also a limited space charge force model. Therefore, we have opted to include the Particle-In-Cell (PIC) code Impact-T as an alternate beam dynamics code to verify the Elegant calculations. We will use the new Line D and RI models to study beam halo in the transport leading into the PSR, and to evaluate collimation schemes as part of the PSR upgrade. The new models can also be readily used in support of other LANSCE activities.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

GPU acceleration and performance of the particle-beam-dynamics code Elegant

Elegant is an accelerator physics and particle-beam dynamics code widely used for modeling and design of a variety of high-energy particle accelerators and accelerator-based systems. We discuss a recently developed version of the code that can take advantage of CUDA-enabled graphics processing units (GPUs) to achieve significantly improved performance for a large class of simulations that are important in practice. The GPU version is largely defined by a framework that simplifies implementations of the fundamental kernel types that are used by Elegant: particle operations, reductions, particle loss, histograms, array convolutions and random number generation. Accelerated performance on the Titan Cray XK-7 supercomputer is approximately 6–10 times better with the GPU than all the CPU cores associated with the same node count. In addition to performance, the maintainability of the GPU-accelerated version of the code was considered a key design objective. Accuracy with respect to the CPU implementation is also a core consideration. Finally, four different methods are used to ensure that the accelerated code faithfully reproduces the CPU results.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Perturbative representation of ultrashort nonparaxial elegant Laguerre-Gaussian fields

An analytical method for calculating the electromagnetic fields of a nonparaxial elegant Laguerre-Gaussian (LG) vortex beam is presented for arbitrary pulse duration, spot size, and LG mode. This perturbative approach provides a numerically tractable model for the calculation of arbitrarily high radial and azimuthal LG modes in the nonparaxial regime, without requiring integral representations of the fields. A key feature of this perturbative model is its use of a Poisson-like frequency spectrum, which allows for the proper description of pulses of arbitrarily short duration. Lastly, this model is thus appropriate for simulating laser-matter interactions, including those involving short laser pulses.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Analytic generalized description of a perturbative nonparaxial elegant Laguerre-Gaussian phasor for ultrashort pulses in the time domain

An analytic expression for a polychromatic phasor representing an arbitrarily short elegant Laguerre-Gauss (eLG) laser pulse of any spot size and LG mode is presented in the time domain as a nonrecursive, closed-form perturbative expansion valid to any order of perturbative correction. Here, this phasor enables the calculation of the complex electromagnetic fields for such beams without requiring the evaluation of any Fourier integrals. It is thus straightforward to implement in analytical or numerical applications involving eLG pulses.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Modeling of the Optical Stochastic Cooling at the IOTA Storage Ring Using ELEGANT

In support of the Optical Stochastic Cooling (OSC) experiment at IOTA, we implemented a high-fidelity model of OSC in ELEGANT. The element is generalizable to any OSC experiment and captures three main behaviors; (i) the longitudinal time of flight OSC, (ii) the effects between the transverse motion of particles in the beam and the transverse distribution of undulator radiation, and (iii) the incoherent contributions of neighboring particles. Together these produce a highly accurate model of OSC and were benchmarked using the results from the IOTA OSC experiment.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

The Solid Angle for a Spherical Surface Source and a Detector with an Arbitrary Aperture: An Elegant Proof

It has previously been proven that the solid angle (or geometry factor, also called the geometrical efficiency) for a spherically symmetric outward-directed surface source with an arbitrary radius and polar angle distribution and an arbitrary detector aperture is equal to the solid angle for an isotropic point source located at the center of the spherical surface source and the same detector aperture. The solid angle for a source-detector system is the fraction of source particles that enter the detector aperture and so it is not purely geometric-the angular distribution of the source is a factor. The previous proof relied on an analytic transport-theory (streaming only) calculation of the solid angle Ω for a spherically symmetric surface source and a point detector. In this paper, a new, more elegant proof is given. Since the net current across any portion of a plane that intersects the center of a spherical surface source is zero, the solid angle for a spherical surface source with any polar angle distribution and a uniform azimuthal angle distribution and any detector aperture is equal to the solid angle for an isotropic point source and the same detector. This insight obviates the calculus and trigonometry involved in the previous proof. (author)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Simulations of Optical Stochastic Cooling with ELEGANT

Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

The Microbiome-Mitochondrion Connection: Common Ancestries, Common Mechanisms, Common Goals

Lynn Margulis in the 1960s elegantly proposed a shared phylogenetic history between bacteria and mitochondria; this relationship has since become a cornerstone of modern cellular biology. Yet, an interesting facet of the interaction between the microbiome and mitochondria has been mostly ignored, that of the systems biology relationship that underpins host health and longevity. Lynn Margulis in the 1960s elegantly proposed a shared phylogenetic history between bacteria and mitochondria; this relationship has since become a cornerstone of modern cellular biology. Yet, an interesting facet of the interaction between the microbiome and mitochondria has been mostly ignored, that of the systems biology relationship that underpins host health and longevity. The mitochondria are descendants of primordial aerobic pleomorphic bacteria (likely genus Rickettsia) that entered (literally and functionally) into a mutualistic partnership with ancient anaerobic microbes (likely Archaea). A stable symbiosis was established, given the metabolic versatility of the early mitochondria, which were capable of providing energy with or without oxygen, whereas nutrient gathering was the assumed responsibility of the host. While microbial relationships with single-cell protists must have occurred in the past, as they occur today, the evolution of multicellular organisms generated a new framework for symbiosis with the microbial world, taking the ancient partnership to an entirely new level. Cell-cell communication between microbes and single-cell protists was augmented through multicellularity to allow distant communication between the host cells and the microbiome, resulting in the development of complex metabolic relationships and an immune system to manage these interactions. Thus, the host is now the body and its resident mitochondria, and the microbiome is an essential supplier of metabolites that act at the level of mitochondria in skeletal muscle to stabilize host metabolism. We humans are caretakers of a profoundly vast and diverse microbiota, the majority of which resides in the gut. Indeed, the microbial genetic diversity of our microbiota outstrips our own by several orders of magnitude, and the cellular abundance is roughly equivalent to our somatic selves. Modern clinical science has elegantly highlighted the importance of the microbiome for metabolic health and well-being. This perspective underscores one fundamental facet of this symbiosis, the ancestral mitochondrion-microbiome axis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Rational Design of Mononuclear Iron Porphyrins for Facile and Selective 4e-/4H+ O2 Reduction: Activation of O-O Bond by 2nd Sphere Hydrogen Bonding

Facile and selective 4e-/4H+ electrochemical reduction of O2 to H2O in aqueous medium has been a sought-after goal for several decades. Elegant but synthetically demanding cytochrome c oxidase mimics have demonstrated selective 4e-/4H+ electrochemical O2 reduction to H2O is possible with rate constants as fast as 105 M-1 s-1 under heterogeneous conditions in aqueous media. Over the past few years, in situ mechanistic investigations on iron porphyrin complexes adsorbed on electrodes have revealed that the rate and selectivity of this multielectron and multiproton process is governed by the reactivity of a ferric hydroperoxide intermediate. The barrier of O-O bond cleavage determines the overall rate of O2 reduction and the site of protonation determines the selectivity. In this report, a series of mononuclear iron porphyrin complexes are rationally designed to achieve efficient O-O bond activation and site-selective proton transfer to effect facile and selective electrochemical reduction of O2 to water. Indeed, these crystallographically characterized complexes accomplish facile and selective reduction of O2 with rate constants >107 M-1 s-1 while retaining >95% selectivity when adsorbed on electrode surfaces (EPG) in water. These oxygen reduction reaction rate constants are 2 orders of magnitude faster than all known heme/Cu complexes and these complexes retain >90% selectivity even under rate determining electron transfer conditions that generally can only be achieved by installing additional redox active groups in the catalyst.

Bhunia, Sarmistha↗
DOE OSTI2016

Detector-device-independent quantum key distribution: Security analysis and fast implementation

One of the most pressing issues in quantum key distribution (QKD) is the problem of detector side-channel attacks. To overcome this problem, researchers proposed an elegant “time-reversal” QKD protocol called measurement-device-independent QKD (MDI-QKD), which is based on time-reversed entanglement swapping. However, MDI-QKD is more challenging to implement than standard point-to-point QKD. Recently, an intermediary QKD protocol called detector-device-independent QKD (DDI-QKD) has been proposed to overcome the drawbacks of MDI-QKD, with the hope that it would eventually lead to a more efficient detector side-channel-free QKD system. Here, we analyze the security of DDI-QKD and elucidate its security assumptions. We find that DDI-QKD is not equivalent to MDI-QKD, but its security can be demonstrated with reasonable assumptions. On the more practical side, we consider the feasibility of DDI-QKD and present a fast experimental demonstration (clocked at 625 MHz), capable of secret key exchange up to more than 90 km.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Nuclear-Electronic Orbital Ehrenfest Dynamics

The recently developed real-time nuclear-electronic orbital (RT-NEO) approach provides an elegant framework for treating electrons and selected nuclei, typically pro- tons, quantum mechanically in nonequilibrium dynamical processes. However, the RT-NEO approach neglects the motion of the other nuclei, preventing a complete de- scription of the coupled nuclear-electronic dynamics and spectroscopy. In this work, we describe the dynamical interaction between the other nuclei and the electron-proton subsystem with the mixed quantum-classical Ehrenfest dynamics method. The NEO- Ehrenfest approach propagates the electrons and quantum protons in a time-dependent variational framework, while the remaining nuclei move classically on the correspond- ing average electron-proton vibronic surface. This approach includes the non-Born- Oppenheimer eects between the electrons and quantum protons with RT-NEO and between the classical nuclei and the electron-proton subsystem with Ehrenfest dynam- ics. Spectral features for vibrational modes involving both quantum and classical nuclei are resolved from the time-dependent dipole moments. Moreover, nuclear quantum ef- fects are included directly in nonadiabatic dynamics simulations. The excited state intramolecular proton transfer in the o-hydroxybenzaldehyde molecule is shown to be faster and to exhibit a larger kinetic isotope eect with NEO-Ehrenfest compared to classical Ehrenfest dynamics. This work shows that the NEO-Ehrenfest method is a powerful tool to study dynamical processes with coupled electronic and nuclear degrees of freedom.

Zhao, Luning↗
DOE OSTI2023

Super-resolution computational saturated absorption microscopy

Imaging beyond the diffraction limit barrier has attracted wide attention due to the ability to resolve previously hidden image features. Of the various super-resolution microscopy techniques available, a particularly simple method called saturated excitation microscopy (SAX) requires only simple modification of a laser scanning microscope: The illumination beam power is sinusoidally modulated and driven into saturation. SAX images are extracted from the harmonics of the modulation frequency and exhibit improved spatial resolution. Unfortunately, this elegant strategy is hindered by the incursion of shot noise that prevents high-resolution imaging in many realistic scenarios. Here, we demonstrate a technique for super-resolution imaging that we call computational saturated absorption (CSA) in which a joint deconvolution is applied to a set of images with diversity in spatial frequency support among the point spread functions (PSFs) used in the image formation with saturated laser scanning fluorescence microscopy. CSA microscopy allows access to the high spatial frequency diversity in a set of saturated effective PSFs, while avoiding image degradation from shot noise.

Murray, Gabe (ORCID:0000000295655485)↗
DOE OSTI2016

ER@CEBAF: Modeling code developments

A proposal for a multiple-pass, high-energy, energy-recovery experiment using CEBAF is under preparation in the frame of a JLab-BNL collaboration. In view of beam dynamics investigations regarding this project, in addition to the existing model in use in Elegant a version of CEBAF is developed in the stepwise ray-tracing code Zgoubi, Beyond the ER experiment, it is also planned to use the latter for the study of polarization transport in the presence of synchrotron radiation, down to Hall D line where a 12 GeV polarized beam can be delivered. This Note briefly reports on the preliminary steps, and preliminary outcomes, based on an Elegant to Zgoubi translation.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Structural Manipulation of Phase Transitions by Self‐Induced Strain in Geometrically Confined Thin Films

Strain engineering is a well-known method often used to tune material properties in thin films. The most studied sources of strain are lattice mismatch and differential thermal contraction between the substrate and film. However, in materials which undergo a structural phase transition (SPT), a third and often overlooked source of strain may play a very significant role. If the substrate confines the area of the film, the SPT may induce stress which changes the evolution of the transition. This is a 2D analog of the isochoric phase transition between water and ice, where the freezing point drops below 0 °C. To illustrate this, the prototypical Mott insulator V 2 O 3 which has an SPT coupled to a metal–insulator transition is used to show how self-induced strain can drastically alter structural and electronic properties. This effect provides an elegant approach for mapping the phase diagram of the SPT and the transitions coupled to it. Moreover, the magnitude of self-straining is tunable by modifying the substrate morphology. Furthermore, this effect may be important for numerous materials which exhibit an SPT and are subjected to geometrical constraints.

Kalcheim, Yoav↗
DOE OSTI2018

Nature‐Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self‐Assembly to DNA Mesophase and Nanocolloids

Abstract Liquid crystals (LCs) are omnipresent in living matter, whose chirality is an elegant and distinct feature in certain plant tissues, the cuticles of crabs, beetles, arthropods, and beyond. Taking inspiration from nature, researchers have recently devoted extensive efforts toward developing chiral liquid crystalline materials with self‐organized nanostructures and exploring their potential applications in diverse fields ranging from dynamic photonics to energy and safety issues. In this review, an account on the state of the art of emerging chiral liquid crystalline nanostructured materials and their technological applications is provided. First, an overview on the significance of chiral liquid crystalline architectures in various living systems is given. Then, the recent significant progress in different chiral liquid crystalline systems including thermotropic LCs (cholesteric LCs, cubic blue phases, achiral bent‐core LCs, etc.) and lyotropic LCs (DNA LCs, nanocellulose LCs, and graphene oxide LCs) is showcased. The review concludes with a perspective on the future scope, opportunities, and challenges in these truly advanced functional soft materials and their promising applications.

Wang, Ling↗
DOE OSTI2022

Complex Oxides for Brain–Inspired Computing: A Review

The fields of brain-inspired computing, robotics, and, more broadly, artificial intelligence (AI) seek to implement knowledge gleaned from the natural world into human-designed electronics and machines. In this review, the opportunities presented by complex oxides, a class of electronic ceramic materials whose properties can be elegantly tuned by doping, electron interactions, and a variety of external stimuli near room temperature, are discussed. The review begins with a discussion of natural intelligence at the elementary level in the nervous system, followed by collective intelligence and learning at the animal colony level mediated by social interactions. An important aspect highlighted is the vast spatial and temporal scales involved in learning and memory. The focus then turns to collective phenomena, such as metal-to-insulator transitions (MITs), ferroelectricity, and related examples, to highlight recent demonstrations of artificial neurons, synapses, and circuits and their learning. First-principles theoretical treatments of the electronic structure, and in situ synchrotron spectroscopy of operating devices are then discussed. The implementation of the experimental characteristics into neural networks and algorithm design is then revewed. Finally, outstanding materials challenges that require a microscopic understanding of the physical mechanisms, which will be essential for advancing the frontiers of neuromorphic computing, are highlighted.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Quaternary organic solar cells enhanced by cocrystalline squaraines with power conversion efficiencies >10%

The incorporation of multiple donors into the bulk-heterojunction layer of organic polymer solar cells (PSCs) has been demonstrated as a practical and elegant strategy to improve photovoltaics performance. However, it is challenging to successfully design and blend multiple donors, while minimizing unfavorable interactions (e.g., morphological traps, recombination centers, etc.). Here, a new Förster resonance energy transfer-based design is shown utilizing the synergistic nature of three light active donors (two small molecules and a high-performance donor–acceptor polymer) with a fullerene acceptor to create highly efficient quaternary PSCs with power conversion efficiencies (PCEs) of up to 10.7%. Within this quaternary architecture, it is revealed that the addition of small molecules in low concentrations broadens the absorption bandwidth, induces cocrystalline molecular conformations, and promotes rapid (picosecond) energy transfer processes. Finally, these results provide guidance for the design of multiple-donor systems using simple processing techniques to realize single-junction PSC designs with unprecedented PCEs.

77 NANOSCIENCE AND NANOTECHNOLOGY↗