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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A transmissive concentrator photovoltaic module with cells directly cooled by silicone oil for solar cogeneration systems

Hybrid concentrator photovoltaic-thermal systems can cogenerate electricity and heat by beam-splitting incoming concentrated light onto photovoltaic cells and a thermal receiver to increase total conversion efficiency and potentially reduce system cost. To demonstrate this, we have designed and prototyped a transmissive spectrum-splitting concentrator photovoltaic module that maximizes solar energy conversion by utilizing the entire solar spectrum. Visible light is collected using infrared-transmissive triple-junction photovoltaic cells to achieve an in-band module efficiency of 43.3% for light of wavelength λ < 873 nm, while 44.2% of out-of-band light with λ > 873 nm is transmitted through for collection by a thermal receiver. During testing on a dual-axis tracked parabolic concentrator dish at up to 166 suns, cell temperatures were maintained at 119 °C or below via a novel active cooling method. This cooling system strictly flows silicone oil directly across both sides of the cells, without inhibiting optical transmission, as verified through experimentation and simulation. The module was validated outdoors for 572 sun·hrs, and achieved a maximum thermal receiver temperature of 180 °C. 86.1% of incident solar power is collected at 166 suns average concentration collectively among the electrical, cooling, and thermal receiver subsystems. The remaining 13.9% is lost to mirror reflectivity, dish shadowing, receiver reflection, and thermal losses. The ability to directly cool the cells with an inert silicone oil offers the potential for reduced system cost relative to previous transmissive hybrid concentrator photovoltaic-thermal systems, including microfluidic-cooled designs. This solar cogeneration capability is valuable in a wide range of commercial and industrial applications.

14 SOLAR ENERGY↗
NASA NTRSDate not supplied

Spectroscopic Investigation of Ungrouped Carbonaceous Chondrites

Carbonaceous (C) chondrites are the most primitive meteorite samples of our solar system. They retain records of their origin, formation mechanisms, evolution and secondary processes. This makes them excellent samples for studies to better understand and shed light on the early history of the solar system. A small fraction of C chondrites is type 2 ungrouped (C2-ung) chondrites. These meteorites could not be easily classified into one of the well-established groups due to compositional/petrological differences and other anomalies [1]. Different starting materials and/or complex post-accretionary processes in the parent bodies may have caused their anomalous compositional properties. As such, chemical characterization of C2-ung chondrites can potentially enable us to differentiate between processes and shed light onto the cosmochemical processes/events that cause such incompatibilities. In this work, we present detailed spectroscopic and imaging data on multiple C2-ung chondrites and compare them with various members of well-established C chondrite groups.

M. Yesiltas↗
NASA NTRS2003

The Sun to the Earth - and Beyond: A Decadal Research Strategy in Solar and Space Physics

The sun is the source of energy for life on earth and is the strongest modulator of the human physical environment. In fact, the Sun's influence extends throughout the solar system, both through photons, which provide heat, light, and ionization, and through the continuous outflow of a magnetized, supersonic ionized gas known as the solar wind. While the accomplishments of the past decade have answered important questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and other solar system bodies, they have also highlighted other questions, some of which are long-standing and fundamental. The Sun to the Earth--and Beyond organizes these questions in terms of five challenges that are expected to be the focus of scientific investigations in solar and space physics during the coming decade and beyond. While the accomplishments of the past decades have answered important questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and other solar system bodies, they have also highlighted other questions, some of which are long-standing and fundamental. This report organizes these questions in terms of five challenges that are expected to be the focus of scientific investigations in solar and space physics during the coming decade and beyond: Challenge 1: Understanding the structure and dynamics of the Sun's interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona. Challenge 2: Understanding heliospheric structure, the distribution of magnetic fields and matter throughout the solar system, and the interaction of the solar atmosphere with the local interstellar medium. Challenge 3: Understanding the space environments of Earth and other solar system bodies and their dynamical response to external and internal influences. Challenge 4: Understanding the basic physical principles manifest in processes observed in solar and space plasmas. Challenge 5: Developing a near-real-time predictive capability for understanding and quantifying the impact on human activities of dynamical processes at the Sun, in the interplanetary medium, and in Earth's magnetosphere and ionosphere. This report summarizes the state of knowledge about the total heliospheric system, poses key scientific questions for further research, and presents an integrated research strategy, with prioritized initiatives, for the next decade. The recommended strategy embraces both basic research programs and targeted basic research activities that will enhance knowledge and prediction of space weather effects on Earth. The report emphasizes the importance of understanding the Sun, the heliosphere, and planetary magnetospheres and ionospheres as astrophysical objects and as laboratories for the investigation of fundamental plasma physics phenomena.

Source record↗
NASA NTRS1993

Response of silicon solar cell to pulsed laser illumination

The response of silicon solar cell(s) to pulsed laser illumination is discussed. The motivation was due to the interest of Earth to space/Moon power beaming applications. When this work began, it was not known if solar cells would respond to laser light with pulse lengths in the nanosecond range and a repetition frequency in the kHz range. This is because the laser pulse would be shorter than the minority carrier lifetime of silicon. A 20-nanosecond (ns) full width half max (FWHM) pulse from an aluminum-gallium/arsenide (Al-Ga-As) diode laser was used to illuminate silicon solar cells at a wavelength of 885 nanometers (nm). Using a high-speed digital oscilloscope, the response of the solar cells to individual pulses across various resistive loads was observed and recorded.

Willowby, D.↗
DOE OSTI2020

Accurate Efficiency Measurements for Emerging PV: A Comparison of NREL's Steady-State Performance Calibration Protocol Between Conventional and Emerging PV Technologies

Emerging PV technologies (e.g. Perovskite, and Quantum Dot) are commonly known to possess challenges for accurate performance measurement under the existing IEC 60904 series of standards, which were developed for conventional Si solar cells. Potential performance artifacts depending on scan rates and directions and light bias exposure history are often seen in those emerging solar cells. To avoid these artifacts and provide an unbiased and reliable efficiency measurement, NREL's Cell and Module Performance (CMP) Group has developed a steady-state performance calibration protocol - the asymptotic P MAX method. In this paper, we applied this procedure to four PV cell technologies, Si, CIGS, perovskite, and Quantum Dot (QD), and compared their performance variations between the transient and the steady-state conditions. By comparison, we found that the performance parameters ( i.e. V OC , I SC , FF, ..eta..) measured between fast I-V scans (and the asymptotic method (steady-state) change significantly for perovskite and QD cells. These changes do not happen for Si and CIGS cells. Furthermore, the statistical performance analysis on nearly 100 emerging cells received globally (including OPV, Perovskite, and QD) shows that over 70 % of the fast I-V scans have a relative performance deviation larger than 1% compared to those determined using the asymptotic P MAX scan. Given the complex dynamic behavior observed in emerging PV devices, the CMP group at NREL thus only certifies their steady steady-state performance using the Asymptotic P MAX method. We highly recommend similar steady-state performance calibration protocol for all researchers in emerging PV because accuracy in reported efficiencies is critical to the long-term success of those promising new PV technologies.

41 EE - Solar Energy Technologies Office (EE-4S)↗
NASA NTRS1972

The impulsive X-ray burst of October 10, 1970.

An impulsive burst of 100-400 keV solar X-rays associated with a small solar flare was observed on October 10, 1970 with a large area scintillator aboard a balloon. The X-ray burst was also observed simultaneously in 10-80 keV range by the OGO-5 satellite and in 8-20 A range by the SOLRAD-9 satellite. The event is attributed to an H-alpha subflare located approximately at S13, E88 on the solar disk. The spectral characteristics of this event are examined in the light of the earlier X-ray observations of small solar flares.

Kane, S. R.↗
NASA NTRS2010

FeatherSail - The Next Generation Nano-Class Sail Vehicle

Solar sail propulsion is a concept, which will soon become a reality. Solar sailing is a method of space flight propulsion, which utilizes the light photons to propel spacecrafts through the vacuum of space. Solar sail vehicles have generally been designed to have a very large area. This requires significant time and expenditures to develop, test and launch such a vehicle. Several notable solar propulsion missions and experiments have been performed and more are still in the development stage. This concept will be tested in the near future with the launch of the NanoSail-D satellite. NanoSail-D is a nano-class satellite, less than 10kg, which will deploy a thin lightweight sheet of reflective material used to propel the satellite in its low earth orbit. The NanoSail-D solar sail design is used for the basic design concept for the next generation of nanoclass solar sail vehicles. The FeatherSail project was started to develop a solar sail vehicle with the capability to perform attitude control via rotating or feathering the solar sails. In addition to using the robust deployment method of the NanoSail-D system, the FeatherSail design incorporates other novel technologies. These technologies include deployable thin film solar arrays and low power, low temperature Silicon-Germanium electronics. Together, these three technological advancements provide a starting point for smaller class sail vehicles. These smaller solar sail vehicles provide a capability for inexpensive missions to explore beyond the realms of low earth orbit.

Alhom, Dave C.↗
NASA NTRS1994

InP solar cell with window layer

The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

Jain, Raj K.↗
NASA NTRS1972

Geomagnetic response to solar activity.

The relationship between solar activity and geomagnetic variations is discussed in the light of spacecraft data obtained during the last decade. The effects of centers of solar activity responsible for producing geomagnetic activity on earth are believed to be transmitted through the solar wind, and there is usually a delay of two or three days before the onset of magnetic activity. Attempts to make a one-to-one correspondence between specific solar events and specific magnetic storms, however, are usually unsuccessful, because of the complex and indirect processes linking the two phenomena. Normally, only statistical tendencies can be shown.

Mead, G. D.↗
NASA NTRS2006

Non-nebular Origin of Dark Mantles Around Chondrules and Inclusions in CM Chondrites

Our examination of nine CM chondrites that span the aqueous alteration sequence leads us to conclude that compact dark fine mantles surrounding chondrules and inclusions in CM chondrites are not discrete fine-grained rims acquired in the solar nebula as modeled by Metzler et al. [Accretionary dust mantles in CM chondrites: evidence for solar nebula processes. Geochim. Cosmochim. Acta 56, 1992, 2873-28971. Nebular processes that lead to agglomeration produce materials with porosities far higher than those in the dark mantles. We infer that the mantles were produced from porous nebular materials on the CM parent asteroid by impact-compaction (a process that produces the lowest porosity adjacent to chondrules and inclusions). Compaction was followed by aqueous alteration that formed tochilinite, serpentine, Ni-bearing sulfide, and other secondary products in voids in the interchondrule regions. Metzler et al. reported a correlation between mantle thickness and the radius of the enclosed object. In Yamato 791 198 we find no correlation when all sizes of central objects and dark lumps are included but a significant correlation (r(sup 2) = 0.44) if we limit consideration to central objects with radii >35 microns; a moderate correlation is also found in QUE 97990. We suggest that impact-induced shear of a plum-pudding-like precursor produced the observed "mantles"; these were shielded from comminution during impact events by the adjacent stronger chondrules and inclusions. Some mantles in CM chondrites with low degrees of alteration show distinct layers that may largely reflect differences in porosity. Typically, a gray, uniform inner layer is surrounded by an outer layer consisting of darker silicates with BSE-bright speckles. The CM-chondrite objects characterized as "primary accretionary rocks" by Metzler et al. did not form in the nebula, but rather on the parent body. The absence of solar-flare particle tracks and solar-wind-implanted rare gases in these clasts reflect their lithified nature and low surface/volume ratios during the period when they resided in the regolith and were subject to irradiation by solar particles. The clasts are analogous to the light-colored metamorphosed clasts in ordinary-chondrite regolith breccias (which also lack solar-flare particle tracks and solar-wind gas).

Trigo-Rodriquez, Josep M.↗
NASA NTRS2000

Evidence of a Supermassive Black Hole in the Galaxy NGC 1023 From The Nuclear Stellar Dynamics

We analyze the nuclear stellar dynamics of the SBO galaxy NGC 1023, utilizing observational data both from the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope and from the ground. The stellar kinematics measured from these long-slit spectra show rapid rotation (V equals approx. 70 km/s at a distance of O.1 deg = 4.9 pc from the nucleus) and increasing velocity dispersion toward the nucleus (where sigma = 295 +/- 30 km/s). We model the observed stellar kinematics assuming an axisymmetric mass distribution with both two and three integrals of motion. Both modeling techniques point to the presence of a central dark compact mass (which presumably is a supermassive black hole) with confidence > 99%. The isotropic two-integral models yield a best-fitting black hole mass of (6.0 +/- 0.4) x 10(exp 7) solar masses and mass-to-light ratio (M/L(sub v)) of 5.38 +/- 0.08, and the goodness-of-fit (CHI(exp 2)) is insensitive to reasonable values for the galaxy's inclination. The three-integral models, which non-parametrically fit the observed line-of-sight velocity distribution as a function of position in the galaxy, suggest a black hole mass of (3.9 +/- 0.4) x 10(exp 7) solar masses and M/L(sub v) of 5.56 +/- 0.02 (internal errors), and the edge-on models are vastly superior fits over models at other inclinations. The internal dynamics in NGC 1023 as suggested by our best-fit three-integral model shows that the velocity distribution function at the nucleus is tangentially anisotropic, suggesting the presence of a nuclear stellar disk. The nuclear line of sight velocity distribution has enhanced wings at velocities >= 600 km/s from systemic, suggesting that perhaps we have detected a group of stars very close to the central dark mass.

Bower, G. A.↗
NASA NTRS1981

Solar cell anomaly detection method and apparatus

A method is provided for detecting cracks and other imperfections in a solar cell, which includes scanning a narrow light beam back and forth across the cell in a raster pattern, while monitoring the electrical output of the cell to find locations where the electrical output varies significantly. The electrical output can be monitored on a television type screen containing a raster pattern with each point on the screen corresponding to a point on the solar cell surface, and with the brightness of each point on the screen corresponding to the electrical output from the cell which was produced when the light beam was at the corresponding point on the cell. The technique can be utilized to scan a large array of interconnected solar cells, to determine which ones are defective.

Miller, Emmett L.↗
NASA NTRS1988

The SOHO project - Coronal and solar wind investigations

The Solar and Heliospheric Observatory (SOHO) satellite mission is planned to study the solar interior, to investigate the physical phenomena related to the formation of the solar corona and the solar wind, and to make in situ measurements of the solar wind. The SOHO instruments designed to study the solar atmosphere and the solar wind are described. The experiments include the study of solar UV radiation, a coronal diagnostic spectrometer, an extreme UV imaging telescope, a UV coronagraph spectrometer, a white light and spectrometric coronagraph, and a study of solar wind anisotropies.

Poland, A. I.↗
NASA NTRS1981

Solar sail Engineering Development Mission

Since photons have momentum, a useful force can be obtained by reflecting sunlight off of a large, low mass surface (most likely a very thin metal-coated plastic film) and robbing the light of some of its momentum. A solar sail Engineering Development Mission (EDM) is currently being planned by the World Space Foundation for the purpose of demonstrating and evaluating solar sailing technology and to gain experience in the design and operation of a spacecraft propelled by sunlight. The present plan is for the EDM spacecraft to be launched (sail stowed) in a spin-stabilized configuration into an initial elliptical orbit with an apogee of 36,000 km and a perigee of a few hundred kilometers. The spacecraft will then use its own chemical propulsion system to raise the perigee to at least 1,200 km. The deployed sail will have an area of 880 sq m and generate a solar force of about 0.007 N.

Price, H. W.↗
NASA NTRS1985

Out-of-Focus Alinement of Solar Concentrators

In new alinement technique, no attempt made to simulate infinitely distant light source, and all mirrors left uncovered throughout procedure. Light source placed at distance of 1,650 feet (503 m); other distances used. Alinement of approximately 250 mirror facets of paraboloidal solar concentrator simplified by precalculated images reflected from all facets. Developed for large solar concentrators, technique used with other multiplemirror or multiple-light-source systems for producing specified illuminance patterns.

Argoud, M. J.↗
NASA NTRS1977

Radiation pressure and Poynting-Robertson drag for small spherical particles

Robertson's expression for the velocity-dependent effect of solar radiation on the motion of small particles is difficult because of its dependence on relativistic considerations, and it is also deficient in that it assumes perfectly absorbing particles. The present paper gives a heuristic derivation of the Poynting-Robertson effect. Robertson's expression for perfectly absorbing particles is obtained but on a much simpler physical basis, and an expression is also obtained for a particle that in general scatters, transmits, and absorbs light. Some numerical results on the solar radiation forces felt by small particles of cosmochemically important compositions are given.

Soter, S.↗
NASA NTRS2000

The Response of the Ionospheric Cusp to the Solar Through Two Perspectives: Low Energy Changed Particle In-Situ Measurements and Low- Energy Neutral Atom Imaging

The IMAGE mission provides a new perspective on the study of the response of the magnetosphere/ionosphere system to changing solar wind conditions, particularly the variability of ion outflow. Learning to interpret this new type of data becomes an essential step in the process of melding these results with the wealth of in-situ charged particle observations obtained over the past 25 years. In order to understand how the in-situ data correspond to and contrast with IMAGE results we will perform a conjunctive study of event data from two instruments to shed light on the coupling of the solar wind and ionosphere from these different perspectives. We will use the Low Energy Neutral Atom instrument (LENA) which images energetic neutral atom emissions from upward flowing ionospheric ions and the Thermal Ion Dynamics Instrument (TIDE) on the Polar satellite which measures in-situ ion outflow from 0.3-300 eV. Our primary goal will be to understand how comparing the imaging and in-situ perspectives can aid in the analysis of both data sets.

Coffey, V. N.↗
NASA NTRS2000

The Response of the Ionospheric Cusp to the Solar Wind Through Two Perspectives: Low Energy Charged Particle In-Situ Measurements and Low-Energy Neutral Atom Imaging

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission provides a new perspective on the study of the response of the magnetosphere/ionosphere system to changing solar wind conditions, particularly the variability of ion outflow. Learning to interpret this new type of data becomes an essential step in the process of melding these results with the wealth of in-situ charged particle observations obtained over the past 25 years. In order to understand how the in-situ data correspond to and contrast with IMAGE results we will perform a conjunctive study of event data from two instruments to shed light on the coupling of the solar wind and ionosphere from these different perspectives. We will use the Low Energy Neutral Atom instrument (LENA) which images energetic neutral atom emissions from upward flowing ionospheric ions and the Thermal Ion Dynamics Instrument (TIDE) on the Polar satellite which measures in-situ ion outflow from 0.3-300 eV. Our primary goal will be to understand how comparing the imaging and in-situ perspectives can aid in the analysis of both data sets.

Coffey, V. N.↗