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At least 991 records · Page 55
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Application of Solar Electric Propulsion to the Low Thrust Lunar Transit of the Gateway Power and Propulsion Element

NASA has committed to returning to the moon, landing the first woman and the next man on its surface. To support a sustained lunar presence, NASA is designing an orbital platform to be assembled in a semi-stable orbit near the moon called the Near Rectilinear Halo Orbit (NRHO). This platform is known as the Gateway and its purpose it to support missions primarily to the lunar south pole. As NASA continues to study ways to reduce the cost of lunar exploration, a simplification implemented in 2020 was combining the first two elements of the Gateway together onto a single commercial launch vehicle (CLV). When launched together, the Power and Propulsion Element (PPE) and NASA’s Habitation and Logistics Outpost (HALO) make up the Co-Manifested Vehicle (CMV). The PPE, a high-power Solar Electric Propulsion (SEP) Stage, will propel the combined stack from a low elliptical orbit to a semi stable orbit near the moon known as a Near Rectilinear Halo Orbit (NRHO). A transit of such a large mass, delivered to the moon from a single launch vehicle is only made possible by the use of the highly efficient SEP low thrust propulsion system. Delivering the same mass via more traditional chemical propulsion systems would require multiple launches and significantly more propellant. This paper captures an overview of the PPE’s SEP system, the lunar transit it will perform to deliver these first two elements of NASA’s Gateway to the NRHO with a comparison of a chemical system performing the same lunar transit to illustrate how SEP enables NASA’s Gateway.

electric propulsion↗
DOE OSTI2022

Next-to-leading power endpoint factorization and resummation for off-diagonal “gluon” thrust

The lack of convergence of the convolution integrals appearing in next-to-leading-power (NLP) factorization theorems prevents the applications of existing methods to resum power-suppressed large logarithmic corrections in collider physics. We consider thrust distribution in the two-jet region for the flavour-nonsinglet off-diagonal contribution, where a gluon-initiated jet recoils against a quark-antiquark pair, which is power-suppressed. With the help of operatorial endpoint factorization conditions, we obtain a factorization formula, where the individual terms are free from endpoint divergences in convolutions and can be expressed in terms of renormalized hard, soft and collinear functions in four dimensions. This allows us to perform the first resummation of the endpoint-divergent SCETI observables at the leading logarithmic accuracy using exclusively renormalization-group methods. The presented approach relies on universal properties of the soft and collinear limits and may serve as a paradigm for the systematic NLP resummation for other 1 → 2 and 2 → 1 collider physics processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Precision DIS thrust predictions for HERA and EIC

We present predictions for the DIS 1-jettiness event shape $τ^b_1$, or DIS thrust, using the framework of Soft Collinear Effective Theory (SCET) for factorization, resummation of large logarithms, and rigorous treatment of nonperturbative power corrections, matched to fixed-order QCD away from the resummation region. Our predictions reach next-to-next-to-next-to-leading-logarithmic (N 3 LL) accuracy in resummed perturbation theory, matched to $\mathcal{O}(α^2_s)$ fixed-order QCD calculations obtained using the program NLOJet++. We include a rigorous treatment of hadronization corrections, which are universal across different event shapes and kinematic variables x and Q at leading power, and supplement them with a systematic scheme to remove $\mathcal{O}$(Λ QCD ) renormalon ambiguities in their definition. The framework of SCET allows us to connect smoothly the nonperturbative, resummation, and fixed-order regions, whose relative importance varies with x and Q, and to rigorously estimate theoretical uncertainties, across a broad range of x and Q covering existing experimental results from HERA as well as expected new measurements from the upcoming Electron- Ion-Collider (EIC). Our predictions will serve as an important benchmark for the EIC program, enabling the precise determination of the QCD strong coupling α s and the universal nonperturbative first moment parameter Ω 1 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Secondary production of massive quarks in thrust

We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e{sup +}e{sup −} → hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N{sup 3}LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(Λ{sub QCD}) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Quantum annealing for jet clustering with thrust

Quantum computing holds the promise of substantially speeding up computationally expensive tasks, such as solving optimization problems over a large number of elements. In high-energy collider physics, quantum-assisted algorithms might accelerate the clustering of particles into jets. In this study, we benchmark quantum annealing strategies for jet clustering based on optimizing a quantity called “thrust” in electron-positron collision events. Here, we find that quantum annealing yields similar performance to exact classical approaches and classical heuristics, after tuning the annealing parameters. Without tuning, comparable performance can be obtained through a hybrid quantum/classical approach.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Mixed deformation styles observed on a shallow subduction thrust, Hikurangi margin, New Zealand

Geophysical observations show spatial and temporal variations in fault slip style on shallow subduction thrust faults, but geological signatures and underlying deformation processes remain poorly understood. International Ocean Discovery Program (IODP) Expeditions 372 and 375 investigated New Zealand’s Hikurangi margin in a region that has experienced both tsunami earthquakes and repeated slow-slip events. We report direct observations from cores that sampled the active Papaku splay fault at 304 m below the seafloor. This fault roots into the plate interface and comprises an 18-m-thick main fault underlain by ~30 m of less intensely deformed footwall and an ~10-m-thick subsidiary fault above undeformed footwall. Fault zone structures include breccias, folds, and asymmetric clasts within transposed and/or dismembered, relatively homogeneous, silty hemipelagic sediments. The data demonstrate that the fault has experienced both ductile and brittle deformation. As a result, this structural variation indicates that a range of local slip speeds can occur along shallow faults, and they are controlled by temporal, potentially far-field, changes in strain rate or effective stress.

58 GEOSCIENCES↗
DOE OSTI2017

The Effect of Krypton Consumption through the Accelerator Channel on Thrust Efficiency of a Morozov’s Stationary Plasma Thruster

Morozov’s stationary plasma thrusters (SPTs) operating on xenon have been successfully used in space technology for many years. At the same time, due to the high cost of xenon, now there is an increased interest in alternative working substances. One of them is krypton. Therefore, research has been conducted earlier on the features of operation and characteristics of SPTs using krypton, which have showed that they are traditional for SPTs. Here, we consider the results of studying the effect of krypton consumption on the thrust efficiency of SPTs. The importance of these results is determined by the fact that they determine the appropriate ranges of SPT regimes when working on krypton.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

thrust iterators

A collection of iterators built on NVIDIA's thrust library driven by a small domain specific language

Brady, Peter↗
DOE OSTI2018

Validation of Deterministic Broadband Ground Motion and Variability from Dynamic Rupture Simulations of Buried Thrust Earthquakes

According to the article, we numerically model broadband ground motion (up to 5–7.5 Hz⁠) from blind‐thrust scenario earthquakes matching the fault geometry of the 1994 Mw 6.7 Northridge earthquake. Several realizations are modeled (by varying the hypocenter location in the dynamic rupture simulation) in a 1D‐layered velocity profile. In addition, we include Q(f )⁠, nonlinear effects from Drucker–Prager plasticity, and superimpose small‐scale medium complexity in both a 1D‐layered and 3D velocity model within the subsequent wave propagation. We investigate characteristics of the ground motion and its variability up to 50 km from the fault by comparing them with ground‐motion prediction equations (GMPEs), simple proxy metrics, as well as strong ground motion records from the Northridge event. We find that median ground motion closely follows the trend predicted by GMPEs and that the intraevent standard deviation, although varying with hypocenter location, lies near that of GMPE models. Plasticity affects ground‐motion amplitudes in regions near the source, reducing intraevent variability above ∼0.5 Hz⁠. Heterogeneity in the velocity structure on both the regional and small scales is needed for the simulated data to match two proxy metrics: the period‐to‐period correlation of spectral acceleration (SA) and the ratio of maximum‐to‐median SA. Although small‐scale heterogeneity has a negligible effect on median SA for this style of rupture, it serves to significantly increase the cumulative absolute velocity, better agreeing with observations. When compared with strong‐motion data, we find that long‐wavelength velocity structure within our deterministic simulations reduces bias at both short and long periods. Finally, synthetic ground motion at both footwall and hanging‐wall sites has no clear dependence on the distance to rupture (at both short and long periods); directivity is likely overpowering any hanging‐wall effect.

Geochemistry & Geophysics↗
DOE OSTI2012

Observation and Simulation of Long-Period Ground Motions In the Persian/Arabian Gulf From Earthquakes in Zagros Thrust Belt

The Arabian Gulf is adjacent to one of the most seismically active fold-and-thrust belts on Earth, the Zagros Mountains. Broadband seismic records of earthquakes in the Zagros Mountains recorded on the Arabian side of the Gulf display long duration surface waves. While shorter periods (< 1 s) are attenuated from crossing the deep sediments (> 10 km) of the Gulf basin, the long period energy is relatively unaffected. Consequently large earthquakes in the Zagros could result in possibly damaging ground motions at long-periods (1-10 s). Such ground motions are of concern for large engineered structures, such as tall buildings and long bridges with resonant periods in the same frequency band (period of 1-10 s).

58 GEOSCIENCES↗
DOE OSTI2014

Data Archive and Portal Thrust Area Strategy Report

This report describes the Data Archive and Portal (DAP), a key capability of the U.S. Department of Energy's Atmosphere to Electron (A2e) initiative. The DAP Thrust Area Planning Group was organized to develop a plan for deploying this capability. Primarily, the report focuses on a distributed system--a DOE Wind Cloud--that functions as a repository for all A2e data. The Wind Cloud will be accessible via an open, easy-to-navigate user interface that facilitates community data access, interaction, and collaboration. DAP management will work with the community, industry, and international standards bodies to develop standards for wind data and to capture important characteristics of all data in the Wind Cloud.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2023

TRACER Carbonaceous Aerosols Thrust – University of California, Davis Field Campaign Report

The broader U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility’s TRacking Aerosol Convection interactions ExpeRiment (TRACER) campaign aims to increase our understanding of convective cloud life cycles and aerosol-convection interactions. Our TRACER Carbonaceous Aerosols Thrust-University of California, Davis (TRACER-CAT-UCDavis) study complemented these broader aims by characterizing and quantifying the optical properties and composition of carbonaceous aerosols during part of the TRACER intensive sampling period (July 1- July 31, 2022) at the first ARM Mobile Facility (AMF1) main site (M1) in La Porte, Texas. Our measurements complemented the suite of instrumentation already provided by the AMF1, expanding the capabilities through deployment of unique, state-of-the-science instrumentation. The instrumentation included: (i) two cavity-attenuated phase shift spectroscopy single-scatter albedo (CAPS-SSA) instruments operating at 530 nm and 630 nm, and that were modified to characterize particle light absorption, extinction, and scattering at elevated humidities; (ii) the UC Davis dual-wavelength cavity ringdown-photoacoustic spectrometer (CRD-PAS), which characterizes dry particle extinction and absorption at 405 nm and 532 nm; (iii) a soot particle aerosol mass spectrometer (SP-AMS) that operated in “laser only” mode that characterized the size-dependent compositions of black carbon (BC)-containing particles; (v) a thermal denuder, to remove coatings on particles; and (vi) a scanning electrical mobility sizer (SEMS), to characterize particle mobility diameters from 10-1300 nm. Our measurements occurred alongside complementary observations made by Los Alamos National Laboratory (LANL) during the TRACER-CAT-LANL study, including a humidified CAPS-SSA instrument operating at 450 nm. Our primary scientific interest is in understanding the relationship between particle composition and light absorption, with a particular focus on the influence of water uptake. While it is known that coatings on BC can enhance absorption, the extent to which this occurs in the atmosphere and the specific role that water plays as a coating remain unclear. The TRACER-CAT-UCDavis measurements were made with near-complete coverage for the CRD-PAS, SP-AMS, and SEMS throughout the intensive period. The UC Davis humidified CAPS-SSA instruments had significant challenges with operation owing to the demanding conditions (large temperature fluctuations, high humidity), exacerbated by supply chain issues that delayed resolution of these challenges. However, the humidified CAPS-SSA instrument operated by LANL operated throughout the intensive period with near-complete coverage. The dry light extinction measurements from the CRD-PAS measurements and the LANL CAPS-SSA exhibited a good correlation, although the CAPS-SSA systematically measured greater extinction values than expected. While all instruments, with the exception of an aerodynamic particle sizer (APS), measured behind a common particulate matter (PM)2.5 μm cyclone, the greater extinction measured by the LANL CAPS-SSA compared to the CRD-PAS may have resulted from different losses of larger particles in the sampling lines from the cyclone to the instruments; the tubing length was shorter from the cyclone to the LANL CAPS-SSA, consistent with this idea. A summary of the TRACER-CAT-UCDavis measurements, along with some of the TRACER-CAT-LANL measurements, are shown in the figure below. Notably, there were periods when the contributions of presumed dust were substantial and even dominated the observed light extinction and absorption. Also, there was a clear shift in the behavior of submicron particles from before July 16, 2022 to after, with the prior period exhibiting regular episodes of new particle formation and the latter period exhibiting rapid variations in the concentrations of small particles.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Energetic Particles - microturbulence interaction thrust (EP SIWG white paper)

This white paper outlines a strategic approach to Energetic Particle (EP) research, aimed at applying the results to the future burning devices such as ITER. Our goal is to deepen the understanding of the interplay between plasma background microturbulence and diverse species of energetic ions in burning plasma devices. This strategy is poised to advance our knowledge in this crucial area of fusion science, paving the way for significant breakthroughs in plasma physics and fusion energy research. We consider the confinement of energetic ions such as auxiliary heating beams, minority ions from ICRH, and fusion product alpha particles. Recent studies have underscored the potential of EP/microturbulence interaction to enhance fusion plasma performance by stabilizing microturbulence. However, it also poses risks, such as exacerbating Alfvénic eigenmode (AE) instabilities, which could compromise the sustainability of plasma discharge by causing EP losses. The interplay between EPs and background microturbulence is evident in the phenomenon of effective pitch angle scattering, a crucial aspect of the quasilinear (QL) theory. This theory is integral to developing numerically-efficient yet comprehensive and self-consistent approaches, recently employed to investigate the relaxation of energetic particle populations in the holistic modeling of fusion-grade plasmas. The primary objectives of this white paper thrust encompass a dual focus. First is that we need to delve into the mechanisms through which microturbulence engenders effective pitch angle scattering. This investigation will entail the examination of the presence of known or self-consistently predicted spectra of modes accountable for microturbulence. In these explorations, electrostatic microturbulence serves as a logical initial stride towards achieving the trust's objectives. This endeavor is anticipated to yield formulations expressing the parametric dependencies of the effective pitch angle scattering frequency on variables such as thermal plasma electron and/or ion temperatures, as well as their respective thermal conductivities. In our second objective, we aim to delve into the intricate formation of zonal flow (ZF) structures amidst the complex interplay of microturbulence and Alfvenic eigenmodes (AEs). This endeavor poses greater challenges as we seek to unravel the macroscopic manifestations influenced by microturbulence, termed as zonal structures (ZS), stemming from microturbulence-induced ZF. Drawing from this understanding, we anticipate employing a QL approach to yield comprehensive insights into the distribution function of energetic particles (EP) within phase space. This method entails resolving the dominant multidimensional phase space diffusion processes while effectively averaging over the rapid ballistic responses. Nevertheless, substantial strides remain imperative to realize a comprehensive whole-device modeling framework. This entails meticulous verification and validation exercises against experimental observations, as well as rigorous benchmarking against theoretical frameworks and numerical simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

EPCAPE-Partitioning Thrust-Los Alamos National Laboratory (EPCAPE-PT-LANL) Field Campaign Report

Coastal cities offer a unique environment for studying aerosol-cloud interactions and the effects of urban emissions on aerosol and cloud properties. As part of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM)’s Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), the Partitioning Thrust by Los Alamos National Laboratory (EPCAPE-PT-LANL) was conducted to complement the science goals of EPCAPE and add additional in-depth measurements of aerosols and clouds at Mt. Soledad. Our campaign focused on measuring the physical, optical, and chemical properties of aerosols, trace gases, and their interactions within marine stratocumulus clouds in La Jolla, California (see Figure 1).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Conversion of Low-Thrust Airplane Gas-Turbine Engines to Power Generators

The local market demand for generators of electric power and heat of output between 7 kW and 2.5 MW is analyzed. State programs relating to the large-scale use of such generators in industry and utility companies are reviewed. Data for generator imports to Russia between 2014 and 2017 suggest that this demand will outstrip supply in the near future. It is expedient to convert low-thrust airplane gas-turbine engines to power generators.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Hydrodynamic Calculation of a Thrust Bearing with an Adapted Profile

Hydrodynamic models are considered for thrust bearings with a profile adapted to the frictional conditions, when operating in incompressible electrically conducting lubricant. The basic operational characteristics of a bearing, with deformation of the frictional pair’s supporting system, are derived on the basis of the equation of motion of the material in the working gap, the continuity equation, and the Darcy and Lamé equations for a thin layer.

36 MATERIALS SCIENCE↗