SEARCH · Engineering Papers

Results for “particle seeding”

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.

SourceResearch connectionFrom yearThrough year

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

At least 289 records · Page 16

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Smartpixels: Towards on-sensor inference of charged particle track parameters and uncertainties

The combinatorics of track seeding has long been a computational bottleneck for triggering and offline computing in High Energy Physics (HEP), and remains so for the HL-LHC. Next-generation pixel sensors will be sufficiently fine-grained to determine angular information of the charged particle passing through from pixel-cluster properties. This detector technology immediately improves the situation for offline tracking, but any major improvements in physics reach are unrealized since they are dominated by lowest-level hardware trigger acceptance. We will demonstrate track angle and hit position prediction, including errors, using a mixture density network within a single layer of silicon as well as the progress towards and status of implementing the neural network in hardware on both FPGAs and ASICs.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2021

Comptonization by reconnection plasmoids in black hole coronae I: Magnetically dominated pair plasma

We perform 2D particle-in-cell simulations of reconnection in magnetically dominated electron–positron plasmas subject to strong Compton cooling. We vary the magnetization σ $\gg$ 1, defined as the ratio of magnetic tension to plasma inertia, and the strength of cooling losses. Magnetic reconnection under such conditions can operate in magnetically dominated coronae around accreting black holes, which produce hard X-rays through Comptonization of seed soft photons. We find that the particle energy spectrum is dominated by a peak at mildly relativistic energies, which results from bulk motions of cooled plasmoids. The peak has a quasi-Maxwellian shape with an effective temperature of ~100 keV, which depends only weakly on the flow magnetization and the strength of radiative cooling. The mean bulk energy of the reconnected plasma is roughly independent of σ, whereas the variance is larger for higher magnetizations. The spectra also display a high-energy tail, which receives ~25 percent of the dissipated reconnection power for σ = 10 and ~40 percent for σ = 40. We complement our particle-in-cell studies with a Monte Carlo simulation of the transfer of seed soft photons through the reconnection layer, and find the escaping X-ray spectrum. The simulation demonstrates that Comptonization is dominated by the bulk motions in the chain of Compton-cooled plasmoids and, for σ ~ 10, yields a spectrum consistent with the typical hard state of accreting black holes.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1980

Fog dispersion

A study of economically viable techniques for dispersing warm fog at commercial airports is presented. Five fog dispersion techniques are examined: evaporation suppression, downwash, mixing, seeding with hygroscopic material, thermal techniques, and charged particle techniques. Thermal techniques, although effective, were found to be too expensive for routine airport operations, and detrimental to the environment. Seeding or helicopter downwash are practical for small-scale or temporary fog clearing, but are probably not useful for airport operations on a routine basis. Considerable disagreement exists on the capability of charged particle techniques, which stems from the fact that different assumptions and parameter values are used in the analytical models. Recommendations resulting from the review of this technique are listed, and include: experimental measurements of the parameters in question; a study to ascertain possible safety hazards, such as increased electrical activity or fuel ignition during refueling operations which could render charged particle techniques impractical; and a study of a single charged particle generator.

Frost, W.↗

DOE OSTI2023

The potential of a TeV-scale muon-ion collider

We propose the development of a novel muon-proton and muon-nucleus collider facility at the TeV scale that is capable of performing precision deep inelastic scattering measurements in new regimes and providing a rich program in nuclear and particle physics. Such a facility could seed, or leverage, the development of a muon-antimuon collider and make use of the existing hadron accelerator infrastructure when sited at a facility such as Brookhaven National Laboratory, Fermilab, or CERN. Here, we discuss the possible energy and luminosity design parameters for several collider configurations, and illustrate the science potential with several studies on deep inelastic scattering kinematics, Higgs and vector boson production, top quark production, and beyond Standard Model leptoquark production. Detector design considerations and a possible road map toward development are also given.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1993

Velocity and drop size measurements in a swirl-stabilized, combusting spray

Velocity and drop size measurements are reported for a swirl-stabilized, combusting spray. For the gas phase, three components of mean and fluctuating velocity are reported. For the droplets, three components of mean and fluctuating velocity, diameter, and number flux are reported. The liquid fuel utilized for all the tests was heptane. The fuel was injected using an air-assist atomizer. The combustor configuration consisted of a center-mounted, air-assist atomizer surrounded by a coflowing air stream. Both the coflow and the atomizing air streams were passed through 45 degree swirlers. The swirl was imparted to both streams in the same direction. The combustion occurred unconfined in stagnant surroundings. The nonintrusive measurements were obtained using a two-component phase/Doppler particle analyzer. The laser-based instrument measured two components of velocity as well as droplet size at a particular point. Gas phase measurements were obtained by seeding the air streams with nominal 1 micron size aluminum-oxide particles and using the measured velocity from that size to represent the gas phase velocity. The atomizing air, coflow air, and ambient surroundings were all seeded with the aluminum-oxide particles to prevent biasing. Measurements are reported at an axial distance of 5 mm from the nozzle. Isothermal single-phase gas velocities are also reported for comparison with the combusting case.

Bulzan, Daniel L.↗

NASA NTRS1984

Production of large-particle-size monodisperse latexes

The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.

Vanderhoff, J. W.↗

DOE OSTI2021

Comparison of divertor behavior and plasma confinement between argon and neon seeding in EAST

The exhaust of excessively high heat and particle fluxes on the divertor target is crucial for EAST long-pulse operation. In the recent EAST experiments, stable partial energy detachment around the upper outer strike point with H 98,y2 ~ 1 was achieved with either Ne or Ar seeding from the upper outer divetor target in the upper single null configuration with ITER-like tungsten divertor. With either Ar or Ne seeding, the electron temperature around the upper outer strike point (T et,UOSP ) was maintained at around 5 eV, the peak temperature of divertor target surface around the upper outer strike point (T div,UO ) decreased significantly, and material sputtering was well suppressed. Here, it was observed that there was less Ar seeding needed for partial energy detachment onset than Ne seeding, which shows that Ar is more efficient in the cooling of T et on the upper outer divertor than Ne. However, there was no detachment on the upper inner divertor with T et around strike point (T et,UISP ) remaining >10 eV with either Ar or Ne seeding from the upper outer divertor. Accompanied with the disappearance of double peak phenomenon of ion flux density on the upper inner divertor target (j s,UI ), the peak T div,UI around the strike point increased to around 300 °C. Although the heat flux on the upper inner divertor target (q t,UI ) is still in the acceptable level, either Ar or Ne seeding only from the upper outer divertor target is not enough to protect the upper inner divertor target from sputtering under current EAST conditions. On the other hand, Ar seeding always causes confinement degradation in the partial energy detachment state. It was observed that there is a slight confinement improvement (~10%) with Ne seeding, which may be due to density peaking, dilution effects and stabilization of the ion temperature gradient mode.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

Mineral-hydrogel composites for mitigating harmful algal bloom and supplying phosphorous for photo-biorefineries

Harmful algal blooms (HAB) are a major environmental concern in eutrophic aquatic systems. To mitigate HABs and recover the phosphorus that drives algal growth, this study developed hydrogel composites seeded with calcium phosphate and wollastonite particles, which first adsorb phosphate (P) and then precipitate it as calcium phosphate. Using a fast-growing cyanobacterium, Synechococcus elongatus 2973, as a model microalga, we found that the mineral-hydrogel composites reduced dissolved P in BG11 media from 5.1 mg/L to 0.31 mg/L, initially reducing the biomass growth rate by up to 73 % and ultimately reducing the total biomass concentration by 75 %. When applied to municipal wastewater and agricultural run-off, the composites removed 96 % and 91 % of the dissolved P, respectively. Moreover, when the recovered P-enriched composites were reused as a slow-release bio-compatible fertilizer in a photobioreactor, they effectively supported algal growth without blocking light and interfering with photosynthesis. The P-enriched composites could tune the P concentration in the culture medium and significantly promote algal lipid accumulation. Finally, this study demonstrates the mineral-hydrogel composites' potential to treat point sources of P pollution and subsequently facilitate photoautotrophic biofuel production as a nutrient, effectively recycling the captured P.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1972

Gas-core reactor power transient analysis.

The nuclear fuel in the gas-core reactor concept is a ball of uranium plasma radiating thermal photons. The photons are met by an inflowing hydrogen stream, which is seeded with submicron size, depleted uranium particles. A 'wall-burnout' condition exists if the thermal photons can reach the cavity liner because of insufficient absorption by the hydrogen. An analysis was conducted in order to determine the time for which the maximum steady state reactor power could be exceeded without damage to the cavity liner due to burnout. Wall-burnout time as a function of the power increase above the initial steady state condition is shown in a graph.

Kascak, A. F.↗

NASA NTRS1976

Radiative behavior of a gas layer seeded with soot

Gaseous film or transpiration cooling may be used to reduce the heat flux reaching the wall of a container or other structures. Such a protective film, however, is usually not effective for reducing radiative heat transfer as most gases are transparent in the temperature range for which solid walls can exist. Therefore, heat transfer was examined for a gaseous layer seeded with radiation-absorbing carbon particles (soot) and flowing along a surface. The layer was subjected to an external high temperature source of blackbody radiation. The radiative behavior was found to depend on a parameter containing particle concentration, layer thickness and source temperature. Only a very small particle volume concentration, in the range of .0001, was required to obtain high absorption in a 1-cm-thick layer for typical conditions. The results provide the distance along the surface for which the heat transfer to the wall remains within an acceptable limit and the particles remain below a temperature at which they will melt or vaporize. The wall protection by the layer lasts only until the particles vaporize or the layer becomes so hot that it reradiates substantially to the wall. Depending on the layer mass velocity the protection may be effective for a distance along the wall of only a few layer thickness. Hence, to protect greater wall lengths, it will be necessary to introduce the suspension through multiple slots or holes along the wall.

Siegel, R.↗

NASA NTRS1976

Natural precedents to active magnetospheric experiments

Some of the natural analogs of proposed seeding experiments in the magnetosphere are: electric charged particle injections during substorms; lightning-induced whistlers providing wave injections; 'detachment' of plasma from the plasmapause, which is equivalent to light-ion seeding in the outer magnetosphere. In the present paper, the characteristics of some natural precedents to active experiments are reviewed, and their relative advantages and drawbacks are examined. One of these precedents - wave generation in detached plasma regions - is then discussed in some detail; the discussion reveals the generation of ELF electromagnetic noise when the energetic electrons exceed the stably trapped limit, and also indicates that a critical dimension for the seeded volume exists transverse to the geomagnetic field.

Russell, C. T.↗

NASA NTRS1993

Development of the seeding system used for laser velocimeter surveys of the NASA Low-Speed Centrifugal Compressor flow field

An atomizer-based system for distributing high-volume rates of seed material was developed to support laser velocimeter investigations of the NASA Low-Speed Centrifugal Compressor flow field. The seeding system and the major concerns that were addressed during its development are described. Of primary importance were that the seed material be dispersed as single particles and that the liquid carrier used be completely evaporated before entering the compressor.

Wasserbauer, Charles A.↗

DOE OSTI2024

One-dimensional simulation and validation of divertor detachment induced through nitrogen seeding on HL-2A

Divertor detachment is a promising method to solve the power exhaust problem in tokamak devices or even in future magnetic fusion reactors. In this work, a detachment experiment (HL-2A shot #38008) with mixed gas seeding (60% nitrogen and 40% deuterium) is simulated using the SD1D module in BOUT++. In the process from attachment to detachment, the target electron temperature and the target ion saturation current in simulations are found to be consistent with the experimental results measured by Langmuir probes on the target plate. In order to understand the underlying detachment mechanism on HL-2A, this work analyses the role of different particle species in the cases with different seeding rates. It shows that the plasma density varies little and the density of neutrals (D and D 2 ) slightly decreases with the increase of nitrogen seeding rate, such that plasma–neutral interactions cannot effectively reduce plasma energy and plasma momentum in the divertor. The case with a high seeding rate predicts that increasing seeding rate cannot reach a target temperature lower than 2.5 eV, which is the required temperature for strong plasma–molecule interactions. Thus, the plasma–molecule interactions may not be important in the divertor during nitrogen seeding. Here this work also studies the parallel forces including (1) force due to the parallel electric field, (2) friction forces, (3) ion- and electron-thermal forces, and (4) collisional reactions (e.g. charge exchange recombination and ionisation). It is found that the friction force between nitrogen ions and other particle species (primarily D + ) is the dominant force towards the target, while ion- and electron-thermal forces are the dominant force pushing nitrogen ions back to upstream. Parallel forces determine the parallel distribution of nitrogen impurities, and therefore decide the region of nitrogen radiation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS1987

Fluidized-Bed Cleaning of Silicon Particles

Fluidized-bed chemical cleaning process developed to remove metallic impurities from small silicon particles. Particles (250 micrometer in size) utilized as seed material in silane pyrolysis process for production of 1-mm-size silicon. Product silicon (1 mm in size) used as raw material for fabrication of solar cells and other semiconductor devices. Principal cleaning step is wash in mixture of hydrochloric and nitric acids, leaching out metals and carrying them away as soluble chlorides. Particles fluidized by cleaning solution to assure good mixing and uniform wetting.

Rohatgi, Naresh K.↗

NASA NTRS1995

Laser diagnostics for microgravity droplet studies

An instrument has been designed, built, and tested for performing laser diagnostic measurements of droplet combustion in low-gravity-flight aircraft. Nonintrusive measurements are of particular importance for droplet combustion (the simplest example of non-premixed combustion) and transport in microgravity environments, where physical contact would introduce an unacceptable level of perturbations. The resolution of these diagnostics can also isolate transport to length scales much smaller than the droplet diameter. These techniques can be configured to instantaneously map an entire flow field in two and three dimensions, providing either qualitative or quantitative information on the distribution of a desired scalar or vector quantity. Detailing the gas-phase flow field and position of the flame front can be achieved using planar laser-induced fluorescence (PLIF) of OH or another flame front marker. An alternative approach is to obtain LIF from a diagnostic seed included in the liquid phase fuel; it would be consumed at the flame front. The main advantage to this approach is that it is easier to choose the wavelength of the molecular absorption which coincides with convenient laser wavelengths rather than finding lasers which can be configured to access OH. Our present method uses a nitrogen-pumped dye laser tuned to a sodium absorption and addition of small concentrations of NaCl to the fuel. Particle image velocimetry (PIV) is a laser-based technique which has recently had its practicality greatly enhanced by the development of high-resolution CCD cameras and the increase in speed and capacity of computer systems. With this technique, a seeded flow is illuminated with a double-pulsed laser sheet to generate a double exposure image on a film or CCD camera. Computer analysis of the image is used to determine the particle velocity vectors and, thus, the gas velocity within the plane of the laser sheet. Our current experiment uses PIV for measuring relative droplet gas-phase velocities in a parabolic flight environment. The results show successful application of PLIF relative to luminosity and radical emission near 308 nm. PIV results are less successful due to gas thermal expansion deflecting the seed particles away from the measurement volume. PIV is applicable for measurements in the absence of combustion.

Winter, Michael↗

DOE OSTI2020

Customized Chiral Colloids

This contribution describes a synthetic strategy for the fabrication of multicomponent colloidal “molecules” with controllable complex morphologies and compositionally distinct lobes. Using 3-(trimethoxysilyl)propyl methacry-late (TPM) as the building block, the methodology enables a scalable bulk synthesis of customized chiral colloidal particles with geometric and compositional chirality by sequential seeded growth method. Finally, the synthetic protocol presents a versatile platform for constructing colloidal molecules with multiple components having customized shapes and functionalities, with the potential to impact the design of chromatic patchy particles, colloidal swimmers and chiral optical materials, as well as informing programmable assembly.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Radiative divertor detachment and impurity transport with nitrogen and neon seeding in KSTAR H-mode plasmas

Achieving core-edge compatible divertor detachment is a critical requirement for stable operation in future fusion devices. This study compares nitrogen and neon seeding in KSTAR H-mode plasmas with carbon walls, combining experiments and SOLPS-ITER modelling to evaluate their radiative dissipation and core-edge compatibility. Experimentally, N seeding achieved stronger divertor detachment, with larger reductions in target particle and heat fluxes, a higher divertor radiation fraction, and a lower core radiation fraction than Ne. In contrast, Ne seeding triggered a significant rise in core radiation followed by H–L back transitions, limiting the maximum total radiated power fraction to roughly half that of N. SOLPS-ITER simulations reproduced the experimental trends and revealed that the better core-edge compatibility of N arises from its higher divertor retention in addition to its higher cooling factor. The relative positions of the stagnation points of impurity poloidal velocity and ionization sources did not explain the different divertor compression. Instead, in the present modelling, the higher impurity parallel particle flux, resulting from the higher parallel impurity velocity, explains the stronger nitrogen impurity compression in the divertor region. The parallel temperature distribution with N was more favourable for achieving higher impurity parallel velocity than with Ne, because the impurity velocity is governed by modifications of the main ion flow due to friction and thermal forces, both of which strongly depend on the temperature. Ultimately, this behaviour is attributed to the strongly divertor-localized radiation of N. These results demonstrate that N is more effective than Ne in achieving radiative divertor detachment while maintaining low core contamination in KSTAR, consistent with observations in other present tokamaks.

KSTAR↗

DOE OSTI2021

Thin-sheet zeolite membrane and methods for making the same

Zeolite membrane sheets for separation of mixtures containing water are provided, as well as methods for making the same. Thin, but robust, zeolite membrane sheets having an inter-grown zeolite crystal film directly on a thin, less than 200 micron thick, porous support sheet free of any surface pores with a size above 10 microns. The zeolite membrane film thickness is less than about 10 microns above the support surface and less than about 5 microns below the support surface. Methods of preparing the membrane are disclosed which include coating of the support sheet surface with a seed coating solution containing the parent zeolite crystals with mean particle sizes from about 0.5 to 2.0 microns at loading of 0.05-0.5 mg/cm2 and subsequent growth of the seeded sheet in a growth reactor loaded with a growth solution over a temperature range of about 45° C. to about 120° C.

Liu, Wei↗