Search NASA⌕ Search

SEARCH · Search NASA

Results for “accelerator performance”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Four-dimensional emittance measurement at the Spallation Neutron Source

A coasting hadron beam with an elliptical transverse profile, uniform charge density, and small transverse four-dimensional (4D) emittance could improve accelerator performance in several contexts. A phase space painting method to generate such a distribution is being tested in the Spallation Neutron Source (SNS) accumulator ring. A critical component of these efforts is to measure the 4D emittance of the beam during accumulation. The 4D emittance can be reconstructed from measured beam profiles in two ways: in the multi-optics method, the optics between a reconstruction and measurement location are varied; in the fixed-optics method, multiple measurement locations are used without modifying the optics. The fixed-optics method is faster but can lead to large uncertainty in the reconstructed 4D emittance. In this paper, we implement a variant of the multi-optics method using the four available wire-scanners near the SNS target. We also modify the wire-scanner region to reduce the uncertainty of the fixed-optics method. We then demonstrate the usefulness of the fixed-optics method by reconstructing the 4D emittance evolution during accumulation in the SNS ring.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Evaluating Autoxidation Radical Scavengers and Additives to Enhance Aminopolymer Sorbent Stability

Solid amine sorbents have shown promise in the removal of ultradilute CO 2 from the atmosphere. Despite being a promising candidate material type for this application, these sorbents are prone to degradation during long-term exposure to environmental components such as CO 2 , O 2 , and H 2 O, with amine oxidation being a particularly challenging problem. In this study, we investigate the potency of different radical scavengers and additives in mitigating the degradation of a model poly- (ethylenimine) (PEI)/Al 2 O 3 sorbent under direct air capture (DAC)-relevant conditions. The results reveal that a 4,4′-bis(α,α- dimethylbenzyl)diphenylamine (BDDPA)-incorporated PEI/Al 2 O 3 sorbent showed the most resistance toward oxidative degradation at varying exposure times and BDDPA loadings under CO 2 -free air (21% O 2 /balance N 2 ) at 120 °C. Interestingly, under humid (∼43% relative humidity (RH) at 26 °C) and dry 0.04% CO 2 -air, the BDDPA/PEI/Al 2 O 3 sorbent showed enhanced sorbent stability both at 70 and 120 °C after 4.5 h of exposure. Under humid CO 2 -free air, at 120 °C, the antioxidant performance slightly declined (in comparison to the dry CO 2 -free air condition) but displayed a much higher stability than the pristine sorbent. Overall, the ability of BDDPA to inhibit sorbent degradation under dry and humid, CO 2 -free and CO 2 -containing (0.04%) air at intermediate (70 °C) and elevated (120 °C) temperatures is promising in prolonging sorbent stability and underscores the importance of performing accelerated oxidation studies in the presence of all species that are expected to be present in DAC processes to identify suitable stabilization treatments for sorbent materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Evolution of Metastable Structures at Bimetallic Surfaces from Microscopy and Machine-Learning Molecular Dynamics

The restructuring of interfaces plays a crucial role in materials science and heterogeneous catalysis. Bimetallic systems, in particular, often adopt very different compositions and morphologies at surfaces compared to the bulk. For the first time, we reveal a detailed atomistic picture of long-time scale restructuring of Pd deposited on Ag using microscopy, spectroscopy, and novel simulation methods. By developing and performing accelerated machine-learning molecular dynamics followed by an automated analysis method, we discover and characterize previously unidentified surface restructuring mechanisms in an unbiased fashion, including Pd-Ag place exchange and Ag pop-out as well as step ascent and descent. Remarkably, layer-by-layer dissolution of Pd into Ag is always preceded by an encapsulation of Pd islands by Ag, resulting in a significant migration of Ag out of the surface and a formation of extensive vacancy pits within a period of microseconds. These metastable structures are of vital catalytic importance, as Ag-encapsulated Pd remains much more accessible to reactants than bulk-dissolved Pd. We report our approach is broadly applicable to complex multimetallic systems and enables the previously intractable mechanistic investigation of restructuring dynamics at atomic resolution.

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

Coherent Strain-Inhibiting Phase Construction of Lithium-Rich Manganese-Based Oxide Toward High Mechanochemical Stability

A layered lithium-rich manganese-based oxide cathode, containing $R\overline{3}m$ (LiTMO 2 , TM = Mn, Ni, Co) and $C2/m$ (Li 2 MnO 3 ) nanodomains, utilizes both transition metals and oxygen redox to yield substantial energy density. However, the inherent heterogeneous nature and distinct nanodomain redox chemistries of layered lithium-rich oxides will inevitably cause pernicious lattice strain and structural displacement, which can hardly be eliminated by conventional doping or coating strategies and result in accelerated performance decay. Herein, we incorporate a strain-inhibiting perovskite phase coherently grown within the layered structure to effectively restrain the displacement and lattice strain during uneven Li-ion extraction. The enhanced mechanochemical stability of the designed cathode benefits the persistent structure and reversible oxygen redox, thereby achieving high initial Coulombic efficiency and stable cycling and voltage profiles. In conclusion, our approach of lattice engineering alleviates the strain and displacement caused by inhomogeneous reactivity between heterogeneous nanodomains and promotes the development of advanced cathode materials with long durability.

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

Thermal management challenges in lithium-ion batteries: understanding heat generation mechanisms

This paper investigates heat generation in commercial 18 650 lithium-ion battery cells and the thermal management challenges from their high energy density and electrochemical processes. Thermal effects can degrade performance, accelerate aging, and increase thermal runaway risk. Using isothermal calorimetry and EIS, the study emphasizes optimizing thermal behavior to improve battery efficiency, safety, and durability.

25 ENERGY STORAGE↗
DOE OSTI2020

GronOR: Massively Parallel and GPU-Accelerated Non-Orthogonal Configuration Interaction for Large Molecular Systems

GronOR is a program package for non-orthogonal configuration interaction calculations for an electronic wave function built in terms of anti-symmetrized products of multi-configuration molecular fragment wave functions. The two-electron integrals that have to be processed may be expressed in terms of atomic orbitals or in terms of an orbital basis determined from the molecular orbitals of the fragments. The code has been specifically designed for execution on distributed memory massively parallel and Graphics Processing Unit (GPU)-accelerated computer architectures, using an MPI+OpenACC/OpenMP programming approach. The task-based execution model used in the implementation allows for linear scaling with the number of nodes on the largest pre-exascale architectures available, provides hardware fault resiliency, and enables effective execution on systems with distinct central processing unit-only and GPU-accelerated partitions. The code interfaces with existing multi-configuration electronic structure codes that provide optimized molecular fragment orbitals, configuration interaction coefficients, and the required integrals. Algorithm and implementation details, parallel and accelerated performance benchmarks, and an analysis of the sensitivity of the accuracy of results and computational performance to thresholds used in the calculations are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Ambient-temperature liquid jet targets for high-repetition-rate HED discovery science

High-power lasers can generate energetic particle beams and astrophysically relevant pressure and temperature states in the high-energy-density (HED) regime. Recently-commissioned high-repetition-rate (HRR) laser drivers are capable of producing these conditions at rates exceeding 1 Hz. However, experimental output from these systems is often limited by the difficulty of designing targets that match these repetition rates. To overcome this challenge, we have developed tungsten microfluidic nozzles, which produce a continuously replenishing jet that operates at flow speeds of approximately 10 m/s and can sustain shot frequencies up to 1 kHz. The ambient-temperature planar liquid jets produced by these nozzles can have thicknesses ranging from hundreds of nanometers to tens of micrometers. In this work, we illustrate the operational principle of the microfluidic nozzle and describe its implementation in a vacuum environment. Further, we provide evidence of successful laser-driven ion acceleration using this target and discuss the prospect of optimizing the ion acceleration performance through an in situ jet thickness scan. Future applications for the jet throughout HED science include shock compression and studies of strongly heated nonequilibrium plasmas. When fielded in concert with HRR-compatible laser, diagnostic, and active feedback technology, this target will facilitate advanced automated studies in HRR HED science, including machine learning-based optimization and high-dimensional statistical analysis.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Radiation, optical, power flow, and electrical diagnostics at the Z facility: Layout and techniques utilized to operate in the harsh environment

The Z machine is a current driver producing up to 30 MA in 100 ns that utilizes a wide range of diagnostics to assess accelerator performance and target behavior conduct experiments that use the Z target as a source of radiation or high pressures. Here, we review the existing suite of diagnostic systems, including their locations and primary configurations. The diagnostics are grouped in the following categories: pulsed power diagnostics, x-ray power and energy, x-ray spectroscopy, x-ray imaging (including backlighting, power flow, and velocimetry), and nuclear detectors (including neutron activation). We will also briefly summarize the primary imaging detectors we use at Z: image plates, x-ray and visible film, microchannel plates, and the ultrafast x-ray imager. The Z shot produces a harsh environment that interferes with diagnostic operation and data retrieval. We term these detrimental processes “threats” of which only partial quantifications and precise sources are known. Finally, we summarize the threats and describe techniques utilized in many of the systems to reduce noise and backgrounds.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Conduct Performance Validation of the Electrodynamic Shield (EDS) Induced Cleaning Under Realistic Environmental Soiling Conditions: CRADA Number CRD-21-17861 (Cooperative Research and Development Final Report)

NREL will work with the Participant to perform accelerated long-term durability and other standard durability tests for prototypes to help demonstrate the reliability of the technology for PV applications. NREL will test commercially relevant-sized prototypes under realistic environmental soiling conditions to correlate dust removal efficacy for improving the PV output under standard solar conditions. Measurements will include voltage-current characterization in solar simulators before and after dust cleaning.

14 SOLAR ENERGY↗
DOE OSTI2025

Basic Research Needs for Inverse Methods for Complex Systems under Uncertainty

Inverse problems, which aim to infer unknown properties of a system using experimental and observational data, are central to addressing many of the U.S. Department of Energy’s (DOE) most critical scientific and engineering challenges. Accurate, computationally efficient, and data-efficient solutions to inverse problems are essential for advancing DOE mission-critical science drivers, including analyzing data from large-scale experimental facilities, optimizing fusion reactor performance, accelerating materials discovery, enhancing geophysical imaging, improving wildfire predictions, and enabling autonomous systems and digital twins. However, these problems are becoming increasingly complex, often involving nonlinear, highdimensional, and interconnected systems and models that span multiple physics and scales, while relying on data with varying quantity, quality, and information content. Compounding these challenges is the uncertainty inherent in DOE-relevant systems, where errors in inputs, noise in data, incompleteness of data, and discrepancies between models and reality constrain the accuracy and precision of solutions. At the same time, the convergence of recent scientific computing trends—scientific machine learning, artificial intelligence, and computing advances such as exascale computing—is creating unprecedented opportunities for tackling these challenges. The cross-cutting nature of inverse problems, combined with their growing complexity and rapidly evolving data and algorithmic demands, strongly motivates the formulation of a prioritized research agenda to maximize their capabilities and impact. In response to this need, DOE’s Advanced Scientific Computing Research (ASCR) program in the Office of Science convened the Workshop on Basic Research Needs for Inverse Problems for Complex Systems Under Uncertainty in June 2025. This workshop brought together experts across disciplines to identify grand challenges and major opportunities in the field. Through collaborative discussions, the workshop defined transformative research directions aimed at addressing the mathematical, statistical, and computational challenges posed by inverse problems under uncertainty. As a result of these efforts, four priority research directions (PRDs) were identified to guide future research and development in this area. These PRDs, summarized below, represent a roadmap for advancing the foundational science and mathematics of inverse problems, enabling robust, scalable, and uncertainty-aware solutions that are critical for DOE applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Steady Spills, Stronger Signals: Machine Learning for Slow Spill Analysis

Particle accelerator experiments rely on stable, consistent proton beams to maximize scientific discovery. This presentation introduces beam spills, duty factor, and beam stability using a meteor shower analogy before exploring how feedback control and machine learning, including recurrent neural networks (RNNs), can analyze spill data, identify patterns, and predict beam behavior. Together, these approaches support beam optimization and improve our understanding of accelerator performance for experiments such as Mu2e.

Prescott, Matthew J. [Fermilab]↗
NASA NTRS1964

The Operation of an Electron-Bombardment Ion Source with Various Gases

The efficiency of the electron-bombardment thrustor is approaching the maximum that can be expected. Desired lifetimes (of the order of 10,000 hr) have not yet been reached, but present knowledge indicates such lifetimes should be obtainable, The simplicity of this thrustor makes it interesting as an ion source for various laboratory experiments. Various gases have been used to determine the ion-chamber and accelerator performance for such applications.

Reader, Paul D.↗
NASA NTRS1978

Diagnostic evaluations of a beam-shielded 8-cm mercury ion thruster

An engineering model thruster fitted with a remotely actuated graphite fiber polyimide composite beam shield was tested in a 3- by 6.5-meter vacuum facility for in-situ assessment of beam shield effects on thruster performance. Accelerator drain current neutralizer floating potential and ion beam floating potential increased slightly when the shield was moved into position. A target exposed to the low density regions of the ion beam was used to map the boundaries of energetic fringe ions capable of sputtering. The particle efflux was evaluated by measurement of film deposits on cold, heated, bare, and enclosed glass slides.

Nakanishi, S.↗
NASA NTRS1978

VEEP: A Vehicle Economy, Emissions, and Performance simulation program

The purpose of the VEEP simulation program was to: (1) predict vehicle fuel economy and relative emissions over any specified driving cycle; (2) calculate various measures of vehicle performance (acceleration, passing manuevers, gradeability, top speed), and (3) give information on the various categories of energy dissipation (rolling friction, aerodynamics, accessories, inertial effects, component inefficiences, etc.). The vehicle is described based on detailed subsystem information and numerical parameters characterizing the components of a wide variety of self-propelled vehicles. Conventionally arranged heat engine powered automobiles were emphasized, but with consideration in the design toward the requirement of other types of vehicles.

Klose, G. J.↗
NASA NTRS1978

Diagnostic evaluations of a beam-shielded 8-cm mercury ion thruster

An engineering model thruster fitted with a remotely actuated graphite fiber polyimide composite beam shield was tested in a 3- by 6.5-meter vacuum facility for in-situ assessment of beam shield effects on thruster performance. Accelerator drain current neutralizer floating potential and ion beam floating potential increased slightly when the shield was moved into position. A target exposed to the low density regions of the ion beam was used to map the boundaries of energetic fringe ions capable of sputtering. The particle efflux was evaluated by measurement of film deposits on cold, heated, bare, and enclosed glass slides.

Nakanishi, S.↗
NASA NTRS1980

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Static and forward speed tests were made in a 40 multiplied by 80 foot wind tunnel of a large-scale, ejector-powered V/STOL aircraft model. Modifications were made to the model following earlier tests primarily to improve longitudinal acceleration capability during transition from hovering to wingborne flight. A rearward deflection of the fuselage augmentor thrust vector was shown to be beneficial in this regard. Other augmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also showed negligible influence on the performance of the wing and of the fuselage augmentor.

Garland, D. B.↗
NASA NTRS1980

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Modifications were made to the model to improve longitudinal acceleration capability during transition from hovering to wing borne flight. A rearward deflection of the fuselage augmentor thrust vector is shown to be beneficial in this regard. Other agmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also shows negligible influence on the performance of the wing and of the fuselage augmentor.

Garland, D. B.↗