Search NASA⌕ Search

SEARCH · Search NASA

Results for “concentration”

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.

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

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Concentration of off-axis radiation by solar concentrators for space power

Off-axis radiation is radiation from any direction not parallel to the axis of the solar concentrator. It will be reflected to regions other than the focus of the parabolic concentrator and possibly concentrated there. Four types of off-axis radiation are discussed. These are: (1) small off-axis angles during walk-off; (2) large off-axis angles; (3) an extended off-axis source such as Earth albedo; and (4) miscellaneous off-axis sources including radio frequency sources and local point sources. A previous analytical study used a computer code named PIXEL to predict concentration of off-axis radiation and a previous experimental study used an 11-m diameter multifaceted dish concentrator to validate the PIXEL analysis. The PIXEL code was limited in that it represented concentration by an ideal parabolic reflector of light from a point source. Another code named OFFSET has been developed to represent the solar concentrator being developed for Space Station Freedom. It is a detailed, ray tracing model which represents 50 ray originating points on the Sun and reflections from 10 points on each of the 456 concentrator facets. Results of this code are generally similar to the PIXEL results although there are small differences due to the more detailed representations of the Sun and concentrator that were used in the OFFSET code.

Jefferies, Kent S.↗
NASA NTRS2003

Flight Experience from Space Photovoltaic Concentrator Arrays and its Implication on Terrestrial Concentrator Systems

Nearly all photovoltaic solar arrays flown in space have used a planar (non- concentrating) design. However, there have been a few notable exceptions where photovoltaic concentrators have been tested and used as the mission s primary power source. Among these are the success experienced by the SCARLET (Solar Concentrator Array with Refractive Linear Element Technology) concept used to power NASA's Deep Space 1 mission and the problems encountered by the original Boeing 702 reflective trough concentrator design. This presentation will give a brief overview of past photovoltaic concentrator systems that have flown in space, specifically addressing the valuable lessons learned from flight experience, and other viable concentrator concepts that are being proposed for the future. The general trends of this flight experience will be noted and discussed with regard to its implications on terrestrial photovoltaic concentrator designs.

Piszczor, Michael F., Jr.↗
DOE OSTI2025

ECON-T and ECON-D: Endcap Concentrator ASICs for the CMS HGCAL

With over 6 million channels, the High Granularity Calorimeter (HGCAL) for the CMS HL-LHC Upgrade presents a unique data challenge. The ECON ASICs provide critical on-detector data reduction for the 40 MHz trigger path (ECON-T) and 750 kHz data acquisition path (ECON-D) of the HGCAL. The ASICs, fabricated in 65 nm CMOS, are rad-tolerant (600 Mrad) with low power consumption (<2.5 mW/channel). This presentation is the first comprehensive description of the ECON designs, first functionality and radiation tests for the ECON-T ASIC, and first results from the full production of 75k ECON-D and ECON-T ASICs.

Bergamin, G. [CERN] (ORCID:0000000285758704)↗
NASA NTRS1992

Global scale concentrations of volcanic activity on Venus: A summary of three 23rd Lunar and Planetary Science Conference abstracts. 1: Venus volcanism: Global distribution and classification from Magellan data. 2: A major global-scale concentration of volcanic activity in the Beta-Atla-Themis region of Venus. 3: Two global concentrations of volcanism on Venus: Geologic associations and implications for global pattern of upwelling and downwelling

As part of the analysis of data from the Magellan Mission, we have compiled a global survey of the location, dimensions, and subsidiary notes of all identified volcanic features on Venus. More than 90 percent of the surface area was examined and the final catalog comprehensively identifies 1548 individual volcanic features larger than approximately 20 km in diameter. Volcanic features included are large volcanoes, intermediate volcanoes, fields of small shield volcanoes, calderas, large lava channels, and lava floods as well as unusual features first noted on Venus such as coronae, arachnoids, and novae.

Crumpler, L. S.↗
NASA NTRS1978

Ozone concentration in the cabin of a Gates Learjet measured simultaneously with atmospheric ozone concentrations

A Gates Learjet Model 23 was instrumented with monitors to measure simultaneously the atmospheric and the cabin concentrations of ozone at altitudes up to 13 kilometers. Six data flights were made in February 1978. Results indicated that only a small amount of the atmospheric ozone is destroyed in the cabin pressurization system. Ozone concentrations measured in the cabin near the conditioned-air outlets were only slightly lower than the atmospheric ozone concentration. For the two cabin configurations tested, the ozone retention in the cabin was 63 and 41 percent of the atmospheric ozone concentration. Maximum cabin ozone concentration measured during these flights was 410 parts per billion by volume.

Briehl, D.↗
NASA NTRS1991

Modeled performance of monolithic, 3-terminal InP/Ga(0.47)In(0.53)As concentrator solar cells as a function of temperature and concentration ratio

Using measured device parameters from a monolithic three-terminal In/GaInAs (0.75 eV) tandem concentrator solar cell, a numerical model is constructed that calculates efficiency as a function of temperature and concentration ratio. The device measurements indicate that the series resistance in the InP top cell severely limits the maximum efficiency at high concentration ratios. Results from the model in which a single-junction InP concentrator solar cell that has a lower resistance by a factor of six was substituted for the top cell show that peak 20 C air-mass-zero (AM0) efficiencies should approach 30 percent at concentration ratios greater than 100. At 80 C, this tandem cell should exceed 24 percent AM0 efficiency.

Osterwald, C. R.↗
DOE OSTI2026

Correlated Ion Transport Governed by Dynamic Local Structure in High Concentration and Localized High Concentration Electrolytes

Understanding the dynamics of cluster formation and network percolation provides the mechanistic link between microscopic solvation structure and transport in concentrated electrolytes, including localized high-concentration electrolytes (LHCEs). Although recent studies have shown LHCEs to form micelle-like aggregates at specific compositions, a quantitative understanding of how solvation structures and transport properties depend on salt–solvent–diluent ratios remains limited. Here, we integrate molecular dynamics with Onsager transport analyses to chart the evolution of solvation microstructure and associated ionic transport in LiFSI/DMC/TTE, achieving good agreement with experimental conductivities across composition. We show that micelle formation arises from a dynamic instability of the cation–anion network, and that network percolation is the primary determinant of conductivity. Two compositional thresholds emerge: A critical network concentration (CNC) and a critical micelle concentration (CMC) that delineate transitions from extended percolating networks to micelle-like clusters and then to fragments. These structural transitions rationalize the nonintuitive conductivity decrease at intermediate dilution despite monotonically decreasing viscosity and provide composition-level design rules for LHCEs.

Mohanakrishnan, Rohith Srinivaas [University of Ca↗
NASA NTRS1991

A high-performance photovoltaic concentrator array - The mini-dome Fresnel lens concentrator with 30 percent efficient GaAs/GaSb tandem cells

A high-efficiency, lightweight space photovoltaic concentrator array is described. Previous work on the minidome Fresnel lens concentrator concept is being integrated with Boeing's 30 percent efficient tandem GaAs/GaSb concentrator cells into a high-performance photovoltaic array. Calculations indicate that, in the near term, such an array can achieve 300 W/sq m at a specific power of 100 W/kg. Emphasis of the program has now shifted to integrating the concentrator lens, tandem cell, and supporting panel structure into a space-qualifiable array. A description is presented of the current status of component and prototype panel testing and the development of a flight panel for the Photovoltaic Array Space Power Plus Diagnostics (PASP PLUS) flight experiment.

Piszczor, M. F.↗
NASA NTRS1976

Concentrations of trace elements and compounds in the airborne suspended particulate matter in Cleveland, Ohio, from August 1971 to August 1972 and their dependence on wind direction: Complete data listing and concentration roses

Concentrations of 75 chemical constituents in the airborne particulate matter were measured in Cleveland, Ohio during 1971 and 1972. Daily values, maxima, geometric means and their standard deviations covering a 1-year period (45 to 50 sampling days) at each of 16 sites are presented on microfiche for 60 elements, and for a lesser number of days for 10 polycyclic aromatic hydrocarbon compounds (PAH), the aliphatic hydrocarbon compounds (AH) as a group and carbon. In addition, concentration roses showing directional properties are presented for 39 elements, 10 PAH and the AH as a group. The elements (except carbon) are shown both in terms of concentration and percentage of the suspended particulate matter.

King, R. B.↗
NASA NTRS1980

Design of nonimaging concentrators as second stages in tandem with image-forming first-stage concentrators

The paper discusses the paraboloidal mirror as a tracking solar concentrator, fitting a nonimaging second stage to the paraboloidal mirror, other image-forming systems as first stages, and tracking systems in two-dimensional geometry. Because of inherent aberrations, the paraboloidal mirror cannot achieve the thermodynamic limit. It is shown how paraboloidal mirrors of short focal ratio and similar systems can have their flux concentration enhanced to near the thermodynamic limit by the addition of nonimaging compound elliptical concentrators.

Winston, R.↗
NASA NTRS1989

Concentration of off-axis radiation by solar concentrators for space power

Four types of off-axis radiation are discussed. These are: (1) small off-axis angles during walk-off, (2) large off-axis angles, (3) an extended off-axis source such as Earth albedo, and (4) miscellaneous off-axis sources including radio frequency sources and local point sources. A code named OFFSET has been developed to represent the solar concentrator being developed for Space Station Freedom. It is a detailed, ray-tracing model which represents 50 ray originating points on the Sun and reflections from 10 points on each of the 456 concentrator facets. Results of this code are generally similar to the PIXEL results although there are small differences due to the more detailed representations of the Sun and concentrator that were used in the OFFSET code.

Jefferies, Kent S.↗
NASA NTRS1994

The response of C1O radical concentrations to variations in NO2 radical concentrations in the lower stratosphere

The respose of ClO concentrations to changes in NO2 concentrations has been inferred from simultaneous observations of (ClO), (NO), (NO2) and (O3) in the midlatitude lower stratosphere. This analysis demonstrates that (ClO) is inversely correlated with (NO2), consistent with formation and photolysis of (ClONO2). A factor of ten range in the concentration if NO2 was sampled (0.1 to 1 x 10(exp 9) mol/cu cm), with a comparable range in the ratio of (ClO) to total available inorganic chlorine (1% less than or equal to (ClO)/(Cl(sub y)) less than or equal to 5%. This analysis leads to an estimate of (ClONO2)/(Cl(sub y)) = 0.12 (x/2), in the mid-latitude, lower-stratospheric air masses sampled.

Stimfle, R. M.↗
NASA NTRS1994

The Response of ClO Radical Concentrations to Variations in NO2 Radical Concentrations in the Lower Stratosphere

The response of ClO concentrations to changes in NO2 concentrations has been inferred from simultaneous observations of [ClO], [NO], [NO2] and [O3] in the mid-latitude lower stratosphere. This analysis demonstrates that [ClO] is inversely correlated with [NO2], consistent with formation and photolysis of [ClONO2]. A factor of ten range in the concentration of NO2 was sampled (0.1 to 1 x 10(exp 9) mol/cc), with a comparable range in the ratio of [ClO] to total available inorganic chlorine (1% <= [ClO]/[Cl(sub y)] <= 5%). This analysis leads to an estimate of [ClONO2]/[Cl(sub y)] = 0.12 (x/divided by 2), in the mid-latitude, lower-stratospheric air masses sampled.

Stimpfle, R. M.↗
DOE OSTI2025

Surprising Relationship between Silicon Anode Calendar Aging and Electrolyte Components in a Localized High-Concentration Electrolyte System

Although localized high-concentration electrolytes (LHCEs) have been shown to improve the calendar lifetime of silicon anodes, the roles of the electrolyte constituents in calendar aging are not well understood. Here, in this work, we utilize a voltage hold protocol and an LHCE with varying molar ratios of lithium bis(fluorosulfonyl)imide (LiFSI), tetramethylene sulfone (TMS), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) to probe the component roles during aging. Interestingly, the estimated calendar lifetime and irreversible lithium losses from the V-hold experiments are independent of the electrolyte formulations. Contrarily, the solid electrolyte interphase (SEI) composition depends on the electrolyte formulation. X-ray photoelectron spectroscopy shows that TMS-coordinated species decompose to form insoluble alkanes and lithium hydroxide (LiOH), while lithium fluoride (LiF) originates from the anion-coordination complex. The SEI composition does not appear to play a significant role in the silicon anode passivity, as measured by parasitic current, suggesting that the SEI-electrolyte interactions dictate the calendar aging mechanisms.

Si anode↗
NASA NTRS1978

Winston Solar Concentrators and Evaluation Support. Phase 2: Non-imaging Concentrators for Space Applications

A 4.67X, plus or minus 5 deg. compound parabolic concentrator (CPC) for a large photovoltaic array in space was analyzed. The design was demonstrated to be effective in achieving a net power gain which can be varied from more than a factor of 3 down to approximately unity. A method for reducing nonuniformities in illumination to a given desired level was found. The effectiveness of this method, which involves the introduction of a degree of non-specularity in the reflector surface, was confirmed by direct measurements with prepared foil reflectors in a CPC in terrestrial sunshine as well as by computer ray tracing. Further ray tracing confirms that the CPC design is extremely tolerant to pointing and alignment errors, minor distortions, etc. A two stage non-imaging design was shown, by preliminary measurements and analysis, to provide both the desired angular tolerance and the required degree of intensity uniformity if higher concentrations (4X-10X) are necessary.

Winston, R.↗
NASA NTRS1980

Conceptual design study of concentrator enhanced solar arrays for space applications. Performance evaluation of 5 KW and 20 KW systems in Si and GaAs at 1 AU employing a flat plate trough concentrator

A simple, efficient and very lightweight preliminary design for a 5 KW and 20 KW BOL output concentrated array evolved and is described by drawings. The relative effectiveness of this design, as compared to an unconcentrated planar array of equal power output, was measured by comparing power to mass performance of and the solar cell area required by each. Improvements in power to mass performance as high as 42% together with array area size reduction of 57% are possible in GaAs systems. By contrast, when the same concentrator design is applied to silicon systems, no improvement in power to mass can be obtained although array area reductions as high as 35% are obtainable.

Source record↗