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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

An investigation into the probabilistic combination of quasi-static and random accelerations

The development of design load factors are investigated for aerospace and aircraft components and experiment support structures, which are subject to a simultaneous vehicle dynamic vibration and acoustically generated random vibration. The characteristics of the combined acceleration probability density function is determined, and an appropriate percentile level for the combined acceleration is selected. This mechanism is developed and graphical data is provided to select combined accelerations for most popular percentile levels.

Schock, R. W.↗
NASA NTRS1974

Study of the use of Metal-Oxide-Silicon (MOS) devices for particulate detection and monitoring in the earth's atmosphere

A metal-oxide-silicon (MOS) capacitor-type particulate sensor was evaluated for use in atmospheric measurements. An accelerator system was designed and tested for the purpose of providing the necessary energy to trigger the MOS-type sensor. The accelerator system and the MOS sensor were characterized as a function of particle size and velocity. Diamond particles were used as particulate sources in laboratory tests. Preliminary tests were performed in which the detector was mounted on an aircraft and flown in the vicinity of coal-fired electric generating plants.

Brooks, A. D.↗
NASA NTRS2006

Role of High-End Computing in Meeting NASA's Science and Engineering Challenges

High-End Computing (HEC) has always played a major role in meeting the modeling and simulation needs of various NASA missions. With NASA's newest 62 teraflops Columbia supercomputer, HEC is having an even greater impact within the Agency and beyond. Significant cutting-edge science and engineering simulations in the areas of space exploration, Shuttle operations, Earth sciences, and aeronautics research, are already occurring on Columbia, demonstrating its ability to accelerate NASA s exploration vision. The talk will describe how the integrated supercomputing production environment is being used to reduce design cycle time, accelerate scientific discovery, conduct parametric analysis of multiple scenarios, and enhance safety during the life cycle of NASA missions.

Biswas, Rupak↗
NASA NTRS2006

Domed, 40-cm-Diameter Ion Optics for an Ion Thruster

Improved accelerator and screen grids for an ion accelerator have been designed and tested in a continuing effort to increase the sustainable power and thrust at the high end of the accelerator throttling range. The accelerator and screen grids are undergoing development for intended use as NASA s Evolutionary Xenon Thruster (NEXT) a spacecraft thruster that would have an input-power throttling range of 1.2 to 6.9 kW. The improved accelerator and screen grids could also be incorporated into ion accelerators used in such industrial processes as ion implantation and ion milling. NEXT is a successor to the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) thruster - a state-of-the-art ion thruster characterized by, among other things, a beam-extraction diameter of 28 cm, a span-to-gap ratio (defined as this diameter divided by the distance between the grids) of about 430, and a rated peak input power of 2.3 kW. To enable the NEXT thruster to operate at the required higher peak power, the beam-extraction diameter was increased to 40 cm almost doubling the beam-extraction area over that of NSTAR (see figure). The span-to-gap ratio was increased to 600 to enable throttling to the low end of the required input-power range. The geometry of the apertures in the grids was selected on the basis of experience in the use of grids of similar geometry in the NSTAR thruster. Characteristics of the aperture geometry include a high open-area fraction in the screen grid to reduce discharge losses and a low open-area fraction in the accelerator grid to reduce losses of electrically neutral gas atoms or molecules. The NEXT accelerator grid was made thicker than that of the NSTAR to make more material available for erosion, thereby increasing the service life and, hence, the total impulse. The NEXT grids are made of molybdenum, which was chosen because its combination of high strength and low thermal expansion helps to minimize thermally and inertially induced deflections of the grids. A secondary reason for choosing molybdenum is the availability of a large database for this material. To keep development costs low, the NEXT grids have been fabricated by the same techniques used to fabricate the NSTAR grids. In tests, the NEXT ion optics have been found to outperform the NSTAR ion optics, as expected.

Soulas, George C.↗
NASA NTRS2000

Failure Engineering Study and Accelerated Stress Test Results for the Mars Global Surveyor Spacecraft's Power Shunt Assemblies

An Engineering-of-Failure approach to designing and executing an accelerated product qualification test was performed to support a risk assessment of a "work-around" necessitated by an on-orbit failure of another piece of hardware on the Mars Global Surveyor spacecraft. The proposed work-around involved exceeding the previous qualification experience both in terms of extreme cold exposure level and in terms of demonstrated low cycle fatigue life for the power shunt assemblies. An analysis was performed to identify potential failure sites, modes and associated failure mechanisms consistent with the new use conditions. A test was then designed and executed which accelerated the failure mechanisms identified by analysis. Verification of the resulting failure mechanism concluded the effort.

Gibbel, Mark↗
NASA NTRSDate not supplied

Parametric Mechanism Design Through Numerical Optimization and Physics Simulation

Design-Build-Test approaches for developing spaceflight hardware are prohibitively time and cost intensive and often lead to suboptimal mechanism designs. Approaches that couple machine learning and high-fidelity physics simulation could eliminate the need for hardware prototyping and dramatically accelerate the engineering design cycle, ultimately reducing cost. This work presents a modular NASA-developed toolchain to optimize hardware mechanisms in a virtual environment using numerical optimization and multi-body physics simulation. The toolchain enables multi-objective optimization, generates parametric CAD files that can be further post-processed by an end user, and can be expanded to optimize full systems and non-mechanical parameters such as feedback control variables. We demonstrate the toolchain through an independently verifiable design problem that optimizes wheel radius to achieve a desired linear velocity in a rigid-body physics environment when the wheel rotates at a constant angular speed, and then post-process the parametric CAD file of the optimal design generated by the tool before ultimately manufacturing it via 3D printing. We end with a discussion of how the toolchain can incorporate other analysis tools, including finite element analysis, computational fluid dynamics, and granular media simulations.

Optimization↗
NASA NTRSDate not supplied

An Optimization-Based Toolchain for Parametric Mechanism Design

Design-Build-Test approaches for developing spaceflight hardware are prohibitively time and cost intensive and often lead to suboptimal mechanism designs. Approaches that couple machine learning and high-fidelity physics simulation could eliminate the need for hardware prototyping and dramatically accelerate the engineering design cycle, ultimately reducing cost. This work presents a modular NASA-developed toolchain to optimize hardware mechanisms in a virtual environment using numerical optimization and multi-body physics simulation. The toolchain enables multi-objective optimization, generates parametric CAD files that can be further post-processed by an end user, and can be expanded to optimize full systems and non-mechanical parameters such as feedback control variables. We demonstrate the toolchain through an independently verifiable design problem that optimizes wheel radius to achieve a desired linear velocity in a rigid-body physics environment when the wheel rotates at a constant angular speed, and then post-process the parametric CAD file of the optimal design generated by the tool before ultimately manufacturing it via 3D printing. We end with a discussion of how the toolchain can incorporate other analysis tools, including finite element analysis, computational fluid dynamics, and granular media simulations.

Optimization↗
NASA NTRSDate not supplied

Optimization-Based Parametric Design via High-Fidelity Simulation: Overview + Examples

Design-Build-Test approaches for developing spaceflight hardware are prohibitively time and cost intensive and often lead to suboptimal mechanism designs. Approaches that couple machine learning and high-fidelity physics simulation could eliminate the need for hardware prototyping and dramatically accelerate the engineering design cycle, ultimately reducing cost. This talk presents a modular NASA-developed toolchain to optimize hardware mechanisms in a virtual environment using numerical optimization and multi-body physics simulation and includes example applications related to rigid wheel design for autonomous rovers and computational fluid dynamics.

optimization↗
NASA NTRS2022

Lunar Transport Vehicle Occupant Protection Requirements

The National Aeronautics and Space Administration (NASA) is preparing for future Artemis missions that will return humans to the lunar surface. A critical piece of these future missions is the Lunar Transport Vehicle (LTV), a transportation device to be used on the lunar surface. A vehicular method of transportation will allow for longer duration missions with increased capabilities to conduct research and transport soil, geological samples, or other materials of interest. Multiple missions to the lunar surface throughout the Apollo program also deployed the use of a lunar vehicle, known as the Lunar Roving Vehicle (LRV). The LRV was used during three of the six Apollo missions that successfully landed humans on the moon. Unfortunately, the LRV did not have any onboard instrumentation, and a large portion of the lunar performance evaluation relied on photographic documentation and crew reports. Therefore, we do not know the actual accelerations and vibrations experienced by the crew when driving on the lunar surface. The objective of this document is to provide occupant protection guidance when designing the LTV. Acceleration, vibration, and jerk metrics imparted by the vehicle relative to the occupant shall not exceed those listed in this document. At the time of writing of these requirements, much of the LTV design is unknown. This document details requirements based on multiple possible restraint configurations and crew orientations.

Kevin R. Dolick↗
DOE OSTI2024

Highly accelerated life testing (HALT): A review from a statistical perspective

Despite its use in one form or another for at least four decades, HALT and related techniques [e.g., highly accelerated-stress screening (HASS) and stress audits (HASA)] are not well understood within the statistical community and remain controversial. This largely reflects a conflict in motivation between engineers, testing under harsh conditions to discover and eliminate failure modes, and statisticians, taking a more cautious approach to develop quantitative estimates of parameters such as mean time between failures (MTBF). Here, this review article will clarify HALT concepts and methods and explain where it fits within the universe of methods that involve the application of accelerating factors to compress the time required to evaluate or enhance product reliability. A major distinction is between methods such as HALT, a high-stress test-analyze-fix-test iterative process directed at improving reliability by discovering and fixing weak points in a design, and quantitative accelerated life testing (QALT), whose goal is the estimation of product life for a fixed design. We discuss methods such as physics of failure that offer some hope of bridging the gap between the qualitative nature of HALT, and purely quantitative statistical methods. We present a variety of engineering applications of HALT including metal fatigue, piping and pressure vessels, structural damage, radiation damage, and rotating machinery. We also discuss potential synergies between HALT and QALT, such as rapid identification, through HALT, of failure modes requiring quantitative analysis. For further study, extensive references to the applicable literature are provided as well as an appendix that describes related methods.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Final Physics Design of Proton Improvement Plan-II At Fermilab

This paper presents the final physics design of the Proton Improvement Plan-II (PIP-II) at Fermilab, focusing on the linear accelerator (Linac) and its beam transfer line. We address the challenges in longitudinal and transverse lattice design, specifically targeting collective effects, parametric resonances, and space charge nonlinearities that impact beam stability and emittance control. The strategies implemented effectively mitigate space charge complexities, resulting in significant improvements in beam quality -- evidenced by reduced emittance growth, lower beam halo, decreased loss, and better energy spread management. This comprehensive study is pivotal for the PIP-II project's success, providing valuable insights and approaches for future accelerator designs, especially in managing nonlinearities and enhancing beam dynamics.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

A high repetition rate millimeter wavelength accelerator for an X-ray free-electron laser

A compact collinear wakefield accelerator has been designed for an X-ray free-electron laser capable of operating at a pulse repetition rate in the tens of kilohertz. The maximum achievable accelerating gradient has been determined, with its limitation linked to beam breakup instability. The fabrication techniques for the principal components of the accelerator including wakefield generation, couplers for excess power extraction and diagnostics, focusing quadrupoles, and a novel undulator have been discussed. Results from various laboratory and beam-based tests on these components have been compared to their original design specifications and demonstrated very good agreement. A preliminary design for the XFEL has been presented, featuring a novel small-period, force-neutral, adjustable-phase undulator.

26 undulator↗
NASA NTRS1974

Physical conditions for conducting radiobiological experiments in beams of accelerated particles with high linear energy transfer

The design and construction of an accelerator to conduct radiobiological experiments is reported that uses aluminum filters to control the accelerated ion beam while preserving its stability, and a vacuum chamber to conduct the ion beam with the help of a collector through a lavsan exit port to the target. Depth distribution of the absorbed dose from a monodirectional ion beam is practically completely represented by the change in the energy spectrum of the biological object.

Kudryashov, Y. I.↗
DOE OSTI2024

Final Physics Design of Proton Improvement Plan-II at Fermilab

This paper presents the final physics design of the Proton Improvement Plan-II (PIP-II) at Fermilab, focusing on the linear accelerator (Linac) and its beam transfer line. We address the challenges in longitudinal and transverse lattice design, specifically targeting collective effects, parametric resonances, and space charge nonlinearities that impact beam stability and emittance control. The strategies implemented effectively mitigate space charge complexities, resulting in significant improvements in beam quality—evidenced by reduced emittance growth, lower beam halo, decreased loss, and better energy spread management. This comprehensive study is pivotal for the PIP-II project's success, providing valuable insights and approaches for future accelerator designs, especially in managing nonlinearities and enhancing beam dynamics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1981

A study on task difficulty and acceleration stress

The results of two experiments which relate to task difficulty and the effects of environmental stress on tracking performance are discussed and compared to subjective evaluations. The first experiment involved five different sum of sine tracking tasks which humans tracked both in a static condition and under a 5 Gz acceleration stress condition. The second experiment involved similar environmental stress conditions but in this case the tasks were constructed from deterministic functions with specially designed velocity and acceleration profiles. Phase Plane performance analysis was conducted to study potential measures of workload or tracking difficulty.

Repperger, D. W.↗
NASA NTRS1993

Detailed analysis of Honeywell In-Space Accelerometer data - STS-32

The Honeywell In-Space Accelerometer (HISA) system collected data in the mid-deck area of the Shuttle Columbia during the flight of STS-32, January 1990. The resulting data were to be used to investigate the response of crystal microstructure to different types of residual acceleration. The HISA is designed to detect and record transient and oscillatory accelerations. The sampling and electronics package stored averaged accelerations over two sampling periods; two sampling rates were available: 1 Hz and 50 Hz. Analysis of the HISA data followed the CMMR Acceleration Data Processing Guide, considering in-house computer modelling of a float-zone indium crystal growth experiment. Characteristic examples of HISA data showing the response to the primary reaction control system, Orbiter Maneuvering System operations, and crew treadmill activity are presented. Various orbiter structural modes are excited by these and other activities.

Rogers, Melissa J. B.↗
NASA NTRS1995

Hypersonic aerodynamics test facility using the external propulsion accelerator

The use of the External propulsion Accelerator (EPA) for launching models of hypersonic aerodynamic configurations into an instrumented ballistic range is discussed. The aerodynamic model is encased inside an axisymmetric projectile designed to be accelerated to high speed in the EPA. Accelerator lengths required to achieve hypersonic speeds are estimated to vary from 10 meters for Mach 7, 40 meters for Mach 10, 150 meters for Mach 15, and 700 meters for Mach 30, assuming a limit of 50,000 g's acceleration. For a model span of 10 cm to 25 cm, the launch tube diameters are 40 cm and 100 cm, respectively. Using this EPA launcher will enable exact simulation of hypersonic flight in ground facilities where both the gas composition and pressure can be controlled in the ballistic range.

Rom, J.↗