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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Metal Hydrides, MOFs, and Carbon Composites as Space Radiation Shielding Mitigators

Recently, metal hydrides and MOFs (Metal-Organic Framework/microporous organic polymer composites - for their hydrogen and methane storage capabilities) have been studied with applications in fuel cell technology. We have investigated a dual-use of these materials and carbon composites (CNT-HDPE) to include space radiation shielding mitigation. In this paper we present the results of a detailed study where we have analyzed 64 materials. We used the Band fit spectra for the combined 19-24 October 1989 solar proton events as the input source term radiation environment. These computational analyses were performed with the NASA high energy particle transport/dose code HZETRN. Through this analysis we have identified several of the materials that have excellent radiation shielding properties and the details of this analysis will be discussed further in the paper.

Atwell, William↗
DOE OSTI2015

Asteroid diversion considerations and comparisons of diversion techniques

The threat of asteroid impacts on Earth poses a low-probability but high consequence risk, with possible outcomes ranging from regional to global catastrophe. However, unique amongst such global threats we have the capability of averting such disasters. Diversion approaches by either kinetic impactor or nuclear energy deposition are the two most practical technologies for mitigating hazardous near Earth asteroids. One of the greatest challenges in understanding our options is the uncertain response of asteroids to such impulsive techniques, due both to our lack of knowledge of the composition and structure of these objects as well as their highly varied nature. Predicting whether we will simply divert or break up a given object is a crucial: the weak self-gravity and inferred weak structure of typical asteroids present the strong possibility the body will fragment for modest impulses. Predictive modeling of failure and fragmentation is one important tool for such studies. In this paper we apply advances in modeling failure and fracture using Adaptive Smoothed Particle Hydrodynamics (ASPH) to understand mega-cratering on asteroids as a validation exercise, and show examples of diverting the near Earth asteroid Bennu using both a kinetic impactor and ablative blow-off due to nuclear energy deposition.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Effects of internal stresses and intermediate phases on the coarsening of coherent precipitates: A phase-field study

Phase stability, topology and size evolution of precipitates are important factors in determining the mechanical properties of crystalline materials. In this article, the Cahn-Hilliard type of phase-field model was coupled to elasticity equations within a mixed-order Galerkin finite element framework to study the coarsening morphology of coherent precipitates. The effects of capillarity, particle size and fraction, compositional strain, and inhomogeneous elasticity on the kinetics and kinematics of coherent precipitates in a binary dual phase crystal admitting a third intermediate stable/meta-stable phase were investigated. The results demonstrated the ability of the model to simulate coarsening under the concomitant action of Ostwald ripening and mismatch elastic strain mechanisms. Using a phenomenological coarsening power law, coarsening rates were determined to depend on precipitate size and volume fraction, compositional strain, and strain mismatch between precipitates and the matrix. Results also showed that the necking incubation time between two neighboring precipitates depends inversely on the precipitate's initial sizes; however, under fixed volume fraction of precipitates, any increase in the initial sizes of the precipitates mitigates the coarsening. Meanwhile, the compositional strain and the growth of the intermediate stable/meta-stable phase leads to substantial enhancements of precipitate coarsening.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Mitigating oxygen loss to improve the cycling performance of high capacity cation-disordered cathode materials

Recent progress in the understanding of percolation theory points to cation-disordered lithium-excess transition metal oxides as high-capacity lithium-ion cathode materials. Nevertheless, the oxygen redox processes required for these materials to deliver high capacity can trigger oxygen loss, which leads to the formation of resistive surface layers on the cathode particles. Here, we demonstrate here that, somewhat surprisingly, fluorine can be incorporated into the bulk of disordered lithium nickel titanium molybdenum oxides using a standard solid-state method to increase the nickel content, and that this compositional modification is very effective in reducing oxygen loss, improving energy density, average voltage, and rate performance. We argue that the valence reduction on the anion site, offered by fluorine incorporation, opens up significant opportunities for the design of high-capacity cation-disordered cathode materials.

25 ENERGY STORAGE↗
NASA NTRS2002

Dust Mitigation for Mars Solar Arrays

Settling of atmospheric dust onto the surface of the solar array is potentially a lifetime-limiting factor for a power system on any Mars mission. For long-term operation of arrays on Mars, it will be necessary to develop techniques to remove deposited dust. Dust is expected to adhere to the array by Van der Waals adhesive forces. These forces are quite strong at the dust particle sizes expected. Dust removal methods must overcome this force. Removal methods can be categorized briefly into four categories: natural, mechanical, electromechanical, and electrostatic. The environment of Mars is expected to be an ideal one for use of electrostatic dust-removal techniques.

Landis, Geoffrey A.↗
NASA NTRS2009

Mitigation of EMU Glove Cut Hazard by MMOD Impact Craters on Exposed ISS Handrails

Recent cut damages to crewmember extravehicular mobility unit (EMU) gloves during extravehicular activity (EVA) onboard the International Space Station (ISS) has been found to result from contact with sharp edges or pinch points rather than general wear or abrasion. One possible source of cut-hazards are protruding sharp edged crater lips from impact of micrometeoroid and orbital debris (MMOD) particles on external metallic handrails along EVA translation paths. During impact of MMOD particles at hypervelocity an evacuation flow develops behind the shock wave, resulting in the formation of crater lips that can protrude above the target surface. In this study, two methods were evaluated to limit EMU glove cut-hazards due to MMOD impact craters. In the first phase, four flexible overwrap configurations are evaluated: a felt-reusable surface insulation (FRSI), polyurethane polyether foam with beta-cloth cover, double-layer polyurethane polyether foam with beta-cloth cover, and multi-layer beta-cloth with intermediate Dacron netting spacers. These overwraps are suitable for retrofitting ground equipment that has yet to be flown, and are not intended to protect the handrail from impact of MMOD particles, rather to act as a spacer between hazardous impact profiles and crewmember gloves. At the impact conditions considered, all four overwrap configurations evaluated were effective in limiting contact between EMU gloves and impact crater profiles. The multi-layer beta-cloth configuration was the most effective in reducing the height of potentially hazardous profiles in handrail-representative targets. In the second phase of the study, four material alternatives to current aluminum and stainless steel alloys were evaluated: a metal matrix composite, carbon fiber reinforced plastic (CFRP), fiberglass, and a fiber metal laminate. Alternative material handrails are intended to prevent the formation of hazardous damage profiles during MMOD impact and are suitable for flight hardware yet to be constructed. Of the four materials evaluated, only the fiberglass formed a less hazardous damage profile than the baseline metallic target. Although the CFRP laminate did not form any noticeable crater lip, brittle protruding fibers are considered a puncture risk. In parallel with EMU glove redesign efforts, modifications to metallic ISS handrails such as those evaluated in this study provide the means to significantly reduce cut-hazards from MMOD impact craters.

Christiansen, Eric L.↗
DOE OSTI2022

Effective antiviral coatings for deactivating SARS-CoV-2 virus on N95 respirator masks or filters

The application of antiviral coatings to masks and respirators is a potential mitigating step toward reducing viral transmission during the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic. The use of appropriate masks, social distancing, and vaccines is the immediate solution for limiting the viral spread and protecting people from this virus. N95 respirator masks are effective in filtering the virus particles, but they cannot kill or deactivate the virus. We report a possible approach to deactivating SARS-CoV-2 by applying an antimicrobial coating (Goldshield 75) to masks and respirators, rendering them suitable for repeated use. Masks coated with Goldshield 75 demonstrated continuous inactivation of the Alpha and Beta variants of the SARS-CoV-2 over a 3-day period and no loss of inactivation when stored at temperatures at 50 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2022

FAST irradiations and initial post irradiation examinations – Part I

The Advanced Fuels Campaign Fission Accelerated Steady-state Test (FAST) at Idaho National Laboratory (INL) completed its first irradiation cycle within the Advanced Test Reactor (ATR). The test focused on the irradiation of alloy fuel forms for use in sodium fast reactors. Tests included the use of fuel additives (Sn, Sb, and Pd) for reducing the gettering of lanthanide fission products, zirconium liners to mitigate fuel-cladding chemical interaction, and annular fuel geometry for sodium-free fuel designs. The first cycle of FAST testing was completed and a series of rodlets were removed for the initial post irradiation examination (PIE) of FAST rodlets. The rodlet irradiation conditions was evaluated using Monte Carlo N-Particle (MCNP) for as-run power history and COMSOL for temperature analysis. These rodlets include a set of low burnups (~2.5 % heavy metal [%FIMA]) control rodlets and a helium bonded annular rodlet (4.7 %FIMA). Initial non-destructive PIE has been completed and includes, visual inspection, neutron radiography and gamma scanning of the FAST rodlets. Radiography confirmed the integrity of the experiments as well as showing the complete filling of the annulus in the annular fuel at a modest burnup (4.7 %FIMA) and potential slumping of the cooler rodlets at lower burnup. Precision gamma scanning indicated mostly usual fission product behavior with the exception of the ceasium in the He-bonded annular fuel. Future destructive PIE will be necessary in order to fully understand the effects of accelerated irradiation on U-Zr metallic fuel behavior.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2011

Generation and Evaluation of Lunar Dust Adhesion Mitigating Materials

Particulate contamination is of concern in a variety of environments. This issue is especially important in confined spaces with highly controlled atmospheres such as space exploration vehicles involved in extraterrestrial surface missions. Lunar dust was a significant challenge for the Apollo astronauts and will be of greater concern for longer duration, future missions. Passive mitigation strategies, those not requiring external energy, may decrease some of these concerns, and have been investigated in this work. A myriad of approaches to modify the surface chemistry and topography of a variety of substrates was investigated. These involved generation of novel materials, photolithographic techniques, and other template approaches. Additionally, single particle and multiple particle methods to quantitatively evaluate the particle-substrate adhesion interactions were developed.

Wohl, Christopher J.↗
DOE OSTI2014

Iron beam acceleration using direct plasma injection scheme

A new set of vanes of radio frequency quadrupole (RFQ) accelerator was commissioned using highly charged iron beam. To supply high intensity heavy ion beams to the RFQ, direct plasma injection scheme (DPIS) with a confinement solenoid was adopted. One of the difficulties to utilize the combination of DPIS and a solenoid field is a complexity of electro magnetic field at the beam extraction region, since biasing high static electric field for ion extraction, RFQ focusing field, and the solenoid magnetic field fill the same space simultaneously. To mitigate the complexity, a newly designed magnetic field clamps were used. The intense iron beam was observed with bunched structure and the total accelerated current reached 2.5 nC.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Protection of extreme ultraviolet lithography masks. II. Showerhead flow mitigation of nanoscale particulate contamination [Protection of EUV lithography masks II: Showerhead flow mitigation of nanoscale particulate contamination]

An analysis is presented of a method to protect the reticle (mask) in an extreme ultraviolet (EUV) mask inspection tool using a showerhead plenum to provide a continuous flow of clean gas over the surface of a reticle. The reticle is suspended in an inverted fashion (face down) within a stage/holder that moves back and forth over the showerhead plenum as the reticle is inspected. It is essential that no particles of 10-nm diameter or larger be deposited on the reticle during inspection. Particles can originate from multiple sources in the system, and mask protection from each source is explicitly analyzed. The showerhead plate has an internal plenum with a solid conical wall isolating the aperture. The upper and lower surfaces of the plate are thin flat sheets of porous-metal material. These porous sheets form the top and bottom showerheads that supply the region between the showerhead plate and the reticle and the region between the conical aperture and the Optics Zone box with continuous flows of clean gas. The model studies show that the top showerhead provides robust reticle protection from particles of 10-nm diameter or larger originating from the Reticle Zone and from plenum surfaces contaminated by exposure to the Reticle Zone. Protection is achieved with negligible effect on EUV transmission. Furthermore, the bottom showerhead efficiently protects the reticle from nanoscale particles originating from the Optics Zone.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Time-resolved measurement of electron beam neutralization

An intense relativistic electron beam (IREB) incident on a target generates positive ions by stimulated and thermal desorption of adsorbed gas, and subsequent electron impact ionization. These ions are accelerated upstream by the beam space-charge potential, thereby partially neutralizing the beam. If there is enough neutralization, the repulsive space-charge force can be overcome by the magnetic-pinch force due to the beam current. This so-called ion focusing is responsible for time dependent defocusing of the radiographic source spot. Since a single monolayer of adsorbed gas has a surface density of about 10 15 /cm 2 and is formed in about one second in a one micro-Torr vacuum, there is always enough adsorbed gas to make this a concern in our accelerators. Therefore, time-resolved measurements of the degree of neutralization are valuable for better understanding of this process with an eye to mitigation for improvement of our radiography. Moreover, these measurements would aid quantification of uncertainties due to these effects when using invasive beam diagnostics, such as OTR imaging targets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

CMS Pixel Telescope Addition to T-980 Bent Crystal Collimation Experiment at the Tevatron

An enhancement to the T-980 bent crystal collimation experiment at the Tevatron has been completed. The enhancement was the installation of a pixel telescope inside the vacuum-sealed beam pipe of the Tevatron. The telescope is comprised of six CMS PSI46 pixel plaquettes, arranged as three stations of horizontal and vertical planes, with the CAPTAN system for data acquisition and control. The purpose of the pixel telescope is to measure beam profiles produced by bent crystals under various conditions. The telescope electronics inside the beam pipe initially were not adequately shielded from the image current of the passing beams. A new shielding approach was devised and installed, which resolved the problem. The noise issues encountered and the mitigating techniques are presented herein, as well as some preliminary results from the telescope.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Development of a machine protection system for the Superconducting Beam Test Facility at Fermilab

Fermilab's Superconducting RF Beam Test Facility currently under construction will produce electron beams capable of damaging the acceleration structures and the beam line vacuum chambers in the event of an aberrant accelerator pulse. The accelerator is being designed with the capability to operate with up to 3000 bunches per macro-pulse, 5Hz repetition rate and 1.5 GeV beam energy. It will be able to sustain an average beam power of 72 KW at the bunch charge of 3.2 nC. Operation at full intensity will deposit enough energy in niobium material to approach the melting point of 2500 C. In the early phase with only 3 cryomodules installed the facility will be capable of generating electron beam energies of 810 MeV and an average beam power that approaches 40 KW. In either case a robust Machine Protection System (MPS) is required to mitigate effects due to such large damage potentials. This paper will describe the MPS system being developed, the system requirements and the controls issues under consideration.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Neutrino factory and beta beam: accelerator options for future neutrino experiments

Two accelerator options for producing intense neutrino beams a Neutrino Factory based on stored muon beams and a Beta Beam facility based on stored beams of beta unstable ions are described. Technical challenges for each are described and current R&D efforts aimed at mitigating these challenges are indicated. Progress is being made in the design of both types of facility, each of which would extend the state-of-the-art in accelerator science.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Design Challenges in High-Current Pulsed Striplines

The Long Baseline Neutrino Facility (LBNF) will produce the worlds most intense neutrino beam. Three series connected magnetic horns will require 5 kV, 300 kA, 800 $\mu$s pulses at a rate of 1.4 Hz to focus the beam. Connecting a single power supply to these focusing horns will require a low impedance connection measuring over 60 m in length. To meet the challenging requirements of connecting the horns to the power supply, this connection is engineered as a nine-conductor, high-current pulsed stripline. It must pass through a harsh radiation environment, be passively cooled, and have an operational lifetime of at least 30 years. This paper discusses mechanical and electrical considerations such as high-voltage holdoff, clamped joint performance, and Lorentz force mitigations in order to meet the specified requirements. The results of tests and experiments on several prototypes of key design features will be presented and discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Multistage coupling of independent laser-plasma accelerators

Laser-plasma accelerators (LPAs) are capable of accelerating charged particles to very high energies in very compact structures. In theory, therefore, they offer advantages over conventional, large-scale particle accelerators. However, the energy gain in a single-stage LPA can be limited by laser diffraction, dephasing, electron-beam loading and laser-energy depletion. The problem of laser diffraction can be addressed by using laser-pulse guiding and preformed plasma waveguides to maintain the required laser intensity over distances of many Rayleigh lengths; dephasing can be mitigated by longitudinal tailoring of the plasma density; and beam loading can be controlled by proper shaping of the electron beam. To increase the beam energy further, it is necessary to tackle the problem of the depletion of laser energy, by sequencing the accelerator into stages, each powered by a separate laser pulse. In this work, we present results from an experiment that demonstrates such staging. Two LPA stages were coupled over a short distance (as is needed to preserve the average acceleration gradient) by a plasma mirror. Stable electron beams from a first LPA were focused to a twenty-micrometre radius-by a discharge capillary-based active plasma lens-into a second LPA, such that the beams interacted with the wakefield excited by a separate laser. Staged acceleration by the wakefield of the second stage is detected via an energy gain of 100 megaelectronvolts for a subset of the electron beam. Changing the arrival time of the electron beam with respect to the second-stage laser pulse allowed us to reconstruct the temporal wakefield structure and to determine the plasma density. Our results indicate that the fundamental limitation to energy gain presented by laser depletion can be overcome by using staged acceleration, suggesting a way of reaching the electron energies required for collider applications.

43 PARTICLE ACCELERATORS↗