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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

A Complete Reporting of MCNP6 Validation Results for Electron Energy Deposition in Single-Layer Extended Media for Source Energies <= 1-MeV

In this paper, we expand on previous validation work by Dixon and Hughes. That is, we present a more complete suite of validation results with respect to to the well-known Lockwood energy deposition experiment. Lockwood et al. measured energy deposition in materials including beryllium, carbon, aluminum, iron, copper, molybdenum, tantalum, and uranium, for both single- and multi-layer 1-D geometries. Source configurations included mono-energetic, mono-directional electron beams with energies of 0.05-MeV, 0.1-MeV, 0.3- MeV, 0.5-MeV, and 1-MeV, in both normal and off-normal angles of incidence. These experiments are particularly valuable for validating electron transport codes, because they are closely represented by simulating pencil beams incident on 1-D semi-infinite slabs with and without material interfaces. Herein, we include total energy deposition and energy deposition profiles for the single-layer experiments reported by Lockwood et al. (a more complete multi-layer validation will follow in another report).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

The ERL Facility PERLE at Orsay

The realisation of the LHeC and the FCC-eh at CERN require the development of the energy recovering technique in multipass mode and for large currents O(10) mA in the SRF cavities. For this purpose, a technology development facility, PERLE, is under design to be built at IJCLab Orsay, which has the key LHeC ERL parameters, in terms of configuration, source, current, frequency and technical solutions, cryomodule, stacked magnets. In this talk we review the design and comment on the status of PERLE.

Bogacz, Alex↗
DOE OSTI2025

Low Frequency Cable Dual Shield Penetration Using Complete Transfer Immittance Model

This report discusses low frequency coupling and subsequent penetration of a dual shield cable using a transfer immittance model with reciprocal sources. Configurations include: 1) where the cable is above a ground plane and shorted at both ends, 2) a monopole arrangement where it is shorted at one end and open at the other end, and 3) a monopole arrangement where the open end is loaded by a disc. The open circuit voltage within the cable is estimated for each case.

42 ENGINEERING↗
NASA NTRS1972

An integrated radiation physics computer code system.

An integrated computer code system for the semi-automatic and rapid analysis of experimental and analytic problems in gamma photon and fast neutron radiation physics is presented. Such problems as the design of optimum radiation shields and radioisotope power source configurations may be studied. The system codes allow for the unfolding of complex neutron and gamma photon experimental spectra. Monte Carlo and analytic techniques are used for the theoretical prediction of radiation transport. The system includes a multichannel pulse-height analyzer scintillation and semiconductor spectrometer coupled to an on-line digital computer with appropriate peripheral equipment. The system is geometry generalized as well as self-contained with respect to material nuclear cross sections and the determination of the spectrometer response functions. Input data may be either analytic or experimental.

Steyn, J. J.↗
NASA NTRS1975

Rarefied gas dynamic effects on mass spectrometric studies of upper planetary atmospheres

Results are presented of measurements obtained with an open-source mass spectrometer both in earth orbit and in a laboratory molecular beam facility. The mass spectrometer/ion source combination was developed in the laboratory to be operable in either of two modes by altering ion extraction potential on ground command, i.e., as a stagnation cavity or to respond only to the incoming molecules of the unperturbed atmosphere. Results indicate that the use of this open-source configuration and dual-mode capability, allied with both standard static calibration and dynamic calibration using high-speed molecular beam techniques in the laboratory, allows collection of useful data on aeronomy of the upper atmosphere of planets and comet tails.

French, J. B.↗
NASA NTRS1987

A finite difference-time domain technique for modeling narrow apertures in conducting scatterers

The finite difference-time domain (FDTD) technique has proven to be a valuable tool for the calculation of the transient and steady state scattering characteristics of relatively complex scatterer and source configurations. In spite of its usefulness, it exhibits serious deficiencies when used to analyze geometries that contain fine detail. An FDTD technique is described that utilizes Babinet's principle to decouple the regions on both sides of the aperture. The result is an FDTD technique that is capable of modeling apertures that are much smaller than the spatial grid used in the analysis and yet is not perturbed by numerical noise when used in the 'scattered field' mode. Numerical results are presented that show the field penetration through cavity-backed apertures that are much smaller than the spatial grid used during the solution.

Demarest, Kenneth R.↗
NASA NTRS1989

Interaction of surface radiation with convection in crystal growth by physical vapor transport

Growth of single crystals from vapor in closed ampoules is governed by an intricate interplay between mass, momentum and heat transfer processes. The objective of this study is to examine and isolate the effects of surface radiation heat transfer on the vapor transport process using a mathematical model. The model consists of a set of coupled nonlinear partial differential equations for conservation of mass, momentum, energy and species, and the integrodifferential equations which represent radiative exchange. It depends on five important physical parameters. These are Grashof number, Prandtl number, Schmidt number, aspect ratio and the radiation-conduction number. The effects of these dimensionless groupings are systematically investigated. From the cases examined, it is concluded that surface radiation can change the flow structure appreciably. This is especially true in microgravity environment where radiation competes primarily with conduction in modifying the thermal profiles. The numerical results also show that in the presence of radiation, the top heating configuration (source on top) is no longer stable and that near the growing crystal, radiation-induced vortices can introduce significant nonuniformities in the growth flux.

Kassemi, Mohammad↗
NASA NTRS1992

Binaural auralization and perceptual verdicality

Early reflection patterns calculated from a room design program were filtered with measured head-related transfer functions (HRTFs) within a 'hypothetical auralization system.' With reference to a particular set of room/listener/sound source configurations, the system is shown to produce both perceptible and imperceptible results. The results of this exploratory analysis are illuminating for future design considerations of HRTF-based auralization systems.

Begault, Durand R.↗
NASA NTRS1998

Finite Element and Plate Theory Modeling of Acoustic Emission Waveforms

A comparison was made between two approaches to predict acoustic emission waveforms in thin plates. A normal mode solution method for Mindlin plate theory was used to predict the response of the flexural plate mode to a point source, step-function load, applied on the plate surface. The second approach used a dynamic finite element method to model the problem using equations of motion based on exact linear elasticity. Calculations were made using properties for both isotropic (aluminum) and anisotropic (unidirectional graphite/epoxy composite) materials. For simulations of anisotropic plates, propagation along multiple directions was evaluated. In general, agreement between the two theoretical approaches was good. Discrepancies in the waveforms at longer times were caused by differences in reflections from the lateral plate boundaries. These differences resulted from the fact that the two methods used different boundary conditions. At shorter times in the signals, before reflections, the slight discrepancies in the waveforms were attributed to limitations of Mindlin plate theory, which is an approximate plate theory. The advantages of the finite element method are that it used the exact linear elasticity solutions, and that it can be used to model real source conditions and complicated, finite specimen geometries as well as thick plates. These advantages come at a cost of increased computational difficulty, requiring lengthy calculations on workstations or supercomputers. The Mindlin plate theory solutions, meanwhile, can be quickly generated on personal computers. Specimens with finite geometry can also be modeled. However, only limited simple geometries such as circular or rectangular plates can easily be accommodated with the normal mode solution technique. Likewise, very limited source configurations can be modeled and plate theory is applicable only to thin plates.

Prosser, W. H.↗
NASA NTRS2006

The Low-Noise Potential of Distributed Propulsion on a Catamaran Aircraft

The noise shielding potential of an inboard-wing catamaran aircraft when coupled with distributed propulsion is examined. Here, only low-frequency jet noise from mid-wing-mounted engines is considered. Because low frequencies are the most difficult to shield, these calculations put a lower bound on the potential shielding benefit. In this proof-of-concept study, simple physical models are used to describe the 3-D scattering of jet noise by conceptualized catamaran aircraft. The Fast Scattering Code is used to predict noise levels on and about the aircraft. Shielding results are presented for several catamaran type geometries and simple noise source configurations representative of distributed propulsion radiation. Computational analyses are presented that demonstrate the shielding benefits of distributed propulsion and of increasing the width of the inboard wing. Also, sample calculations using the FSC are presented that demonstrate additional noise reduction on the aircraft fuselage by the use of acoustic liners on the inboard wing trailing edge. A full conceptual aircraft design would have to be analyzed over a complete mission to more accurately quantify community noise levels and aircraft performance, but the present shielding calculations show that a large acoustic benefit could be achieved by combining distributed propulsion and liner technology with a twin-fuselage planform.

Posey, Joe W.↗
NASA NTRS2007

Simulation Environment for Orion Launch Abort System Control Design Studies

The development and use of an interactive environment to perform control system design and analysis of the proposed Crew Exploration Vehicle Launch Abort System is described. The environment, built using a commercial dynamic systems design package, includes use of an open-source configuration control software tool and a collaborative wiki to coordinate between the simulation developers, control law developers and users. A method for switching between multiple candidate control laws and vehicle configurations is described. Aerodynamic models, especially in a development program, change rapidly, so a means for automating the implementation of new aerodynamic models is described.

McMinn, J. Dana↗
NASA NTRS2010

Selectivity enhancement in photoacoustic gas analysis via phase-sensitive detection at high modulation frequency

A method for detecting a target fluid in a fluid sample comprising a first fluid and the target fluid using photoacoustic spectroscopy (PAS), comprises a) providing a light source configured to introduce an optical signal having at least one wavelength into the fluid sample; b) modulating the optical signal at a desired modulation frequency such that the optical signal generates an acoustic signal in the fluid sample; c) measuring the acoustic signal in a resonant acoustic detector; and d) using the phase of the acoustic signal to detect the presence of the target fluid.

Kosterev, Anatoliy↗
NASA NTRS2013

Global Propagation of Gravity Waves Generated with the Whole Atmosphere Transfer Function Model

A brief review is presented of the Transfer Function Model (TFM) [e.g., Mayr et al., Space Science Reviews, 1990], which describes acoustic gravity waves (AGW) that propagate across the globe in a dissipative and static (no winds) background atmosphere with globally uniform temperature and density variations extending from the ground to 700 km. Unique among existing models, the TFM can be placed between the analytical approach on one end, and the rigorous numerical approach of general circulation models (GCM). The time consuming numerical integration of the conservation equations is restricted to compute the transfer function (TF) for a broad range of frequencies and spherical harmonics. Given TF, the atmospheric response for a chosen source configuration is then obtained in short order. Computationally efficient, the model is well suited to serve as experimental and educational tool for simulating propagating wave patterns across the globe. By design, the TFM is also semi-analytical and therefore well suited to explore the different wave modes that can be generated under different dynamical conditions.

Transfer Function Model↗
NASA NTRS2021

Microsphere Plutonium-238 Oxide Fuel to Revolutionize New Radioisotope Power Systems and Heat Sources for Planetary Exploration

Microsphere 238PuO2 fuels have potential to provide performance and safety enhancements for future radioisotope heat and power systems (RPS) as well as enable more flexible and compact RPS designs. Improvements in RPS specific power and more flexible geometries were recently investigated by JPL and PNNL as part of a study on cryobot devices for exploring Ocean Worlds. Missions to penetrate ice and explore oceans, such as on Europa, will require RPS with high specific power within the vehicle to provide both heat and power. Such missions will be mass-constrained, and the energy required to penetrate the ice is highly dependent on cryobot size. Therefore, compact RPS geometries are needed to maximize heat and power while minimizing 238Pu inventory. Microsphere-based heat sources are an attractive way to obtain flexible geometries and high volumetric power loadings because they can fill a region of any size and shape provided fuel temperatures are kept below a threshold and launch/re-entry safety are not compromised. The sol-gel technique to produce 238PuO2 microsphere particles for heat sources has the benefit of preventing dust generation, as opposed to the current 238PuO2 powder/pellet processing method, reducing hazards in the fuel fabrication line. Microspheres can also be individually coated to enhance thermal conductivity, and/or reduce the likelihood of 238PuO2 fuel dispersal in an accident. Although PNNL has produced 238PuO2 microspheres using the sol-gel method, the application of coatings and their integrity over time has yet to be investigated. Continued R&D could demonstrate the feasibility of advanced, microspherebased heat sources and provide baseline data for planning future missions requiring new RPS with different heat source configurations.

Fleurial, Jean-Pierre↗
DOE OSTI2018

High-speed volume measurement system

Disclosed is a volume sensor having a first axis, a second axis, and a third axis, each axis including a laser source configured to emit a beam; a parallel beam generating assembly configured to receive the beam and split the beam into a first parallel beam and a second parallel beam, a beam-collimating assembly configured to receive the first parallel beam and the second parallel beam and output a first beam sheet and a second beam sheet, the first beam sheet and the second beam sheet being configured to traverse the object aperture; a first collecting lens and a second collecting lens; and a first photodetector and a second photodetector, the first photodetector and the second photodetector configured to output an electrical signal proportional to the object; wherein the first axis, the second axis, and the third axis are arranged at an angular offset with respect to each other.

42 ENGINEERING↗
DOE OSTI2018

Methods and systems for calibration of particle detectors

Techniques for calibration of particle detectors are disclosed. In one aspect, a system for calibrating a particle detector includes a source configured to emit particles including a first and a second type of particles; a first and a second shielding unit configured to be removably positioned in a travel path of the particles and configured to block at least a portion of the first type of particles and to allow the second type of particles to traverse substantially unimpeded there through; one or more particle detectors positioned in the travel path of the particles to receive particles after traversing through the first or the second shielding unit and produce electronic pulses in response to the detection of the particles; and a processor coupled to the one or more particle detectors to generate training date and a classifier that allows classification of the first and the second types of particles.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Controlled microwave assisted synthesis of functionalized silica nanoparticles

A method of synthesizing silica nanoparticles. The method includes hydrolyzing a silica precursor to form a plurality of monomers, each monomer of the plurality comprising a microwave reactive silicon species. The plurality of monomers is irradiated by an energy source configured to generate microwave frequency energy. Irradiation cases the plurality of monomers polymerize into a silica nanoparticle.

36 MATERIALS SCIENCE↗