Experimental study of effects of simulated neutralized solar wind on white-pigment thermal control coatings
Simulated solar wind effects on thermal control coatings for space flight
Cannaday, S. S.↗
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Results for “Solar White”
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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Resource Analysis of NP Kunta Solar Park Site (White Paper)
India has set a target of 175 GW of renewable energy (RE) capacity by 2022 and 450 GW by 2030. Flexibility is key for efficient integration of renewables. The modern-day RE plants are grid-friendly and can also provide this flexibility. A pilot to demonstrate this flexibility by implementing automatic generation control (AGC) at a solar plant is being done by the U.S. Agency for International Development (USAID) under USAID’s Greening the Grid (GTG) Program and Renewable Integration & Sustainable Energy (RISE) initiative. This paper presents the resource variability analysis of the 250-MW NP Kunta solar plant site where the AGC pilot project is being implemented. This paper also demonstrates the use of publicly available resource quality data, which can be utilized by various stakeholders to better understand the variability of any existing or potential RE site in India and possibly increase confidence in decisions or help to understand the impacts that can be expected.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Contamination from Skylab as determined from the solar coronagraph data
The white light solar coronagraph was one of the scientific telescopes flown on Skylab to study the sun. It studied the sun's atmosphere located from 0.5 to 5.0 solar radii above the sun's limb. Such a telescope is so sensitive to contamination around the spacecraft that it caused a major contamination abatement program to be initiated at the conception of Skylab. The coronagraph's data is analyzed showing the successfulness of that abatement program.
Mcguire, J. P.↗
The accretion of solar material onto white dwarfs: No mixing with core material implies that the mass of the white dwarf is increasing
Cataclysmic Variables (CVs) are close binary star systems with one component a white dwarf (WD) and the other a larger cooler star that fills its Roche Lobe. The cooler star is losing mass through the inner Lagrangian point of the binary and some unknown fraction of this material is accreted by the WD. One consequence of the WDs accreting material, is the possibility that they are growing in mass and will eventually reach the Chandrasekhar Limit. This evolution could result in a Supernova Ia (SN Ia) explosion and is designated the Single Degenerate Progenitor (SD) scenario. This paper is concerned with the SD scenario for SN Ia progenitors. One problem with the single degenerate scenario is that it is generally assumed that the accreting material mixes with WD core material at some time during the accretion phase of evolution and, since the typical WD has a carbon-oxygen CO core, the mixing results in large amounts of carbon and oxygen being brought up into the accreted layers. The presence of enriched carbon causes enhanced nuclear fusion and a Classical Nova explosion. Both observations and theoretical studies of these explosions imply that more mass is ejected than is accreted. Thus, the WD in a Classical Nova system is losing mass and cannot be a SN Ia progenitor. However, the composition in the nuclear burning region is important and, in new calculations reported here, the consequences to the WD of no mixing of accreted material with core material have been investigated so that the material involved in the explosion has only a Solar composition. WDs with a large range in initial masses and mass accretion rates have been evolved. I find that once sufficient material has been accreted, nuclear burning occurs in all evolutionary sequences and continues until a thermonuclear runaway (TNR) occurs and the WD either ejects a small amount of material or its radius grows to about 10{sup 12} cm and the evolution is ended. In all cases where mass ejection occurs, the mass of the ejecta is far less than the mass of the accreted material. Therefore, all the WDs are growing in mass. It is also found that the accretion time to explosion can be sufficiently short for a 1.0M{sub ⊙} WD that recurrent novae can occur on a low mass WD. This mass is lower than typically assumed for the WDs in recurrent nova systems. Finally, the predicted surface temperatures when the WD is near the peak of the explosion imply that only the most massive WDs will be significant X-ray emitters at this time.
79 ASTRONOMY AND ASTROPHYSICS↗
CORRELATION OF HARD X-RAY AND WHITE LIGHT EMISSION IN SOLAR FLARES
A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and Helioseismic and Magnetic Imager. We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 Å summed over the hard X-ray flare ribbons with an integration time of 45 s around the peak hard-X ray time. We find a good correlation between hard X-ray fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ∼50 keV. At higher electron energies the correlation decreases gradually while a rapid decrease is seen if the energy provided by low-energy electrons is added. This suggests that flare-accelerated electrons of energy ∼50 keV are the main source for white light production.
79 ASTRONOMY AND ASTROPHYSICS↗
Revisiting the Solar Research Cyberinfrastructure Needs: A White Paper of Findings and Recommendations
Solar and Heliosphere physics are areas of remarkable data-driven discoveries. Recent advances in high cadence, high-resolution multiwavelength observations, growing amounts of data from realistic modeling, and operational needs for uninterrupted science-quality data coverage generate the demand for a solar metadata standardization and overall healthy data infrastructure. This white paper is prepared as an effort of the working group “Uniform Semantics and Syntax of Solar Observations and Events” created within the “Towards Integration of Heliophysics Data, Modeling, and Analysis Tools” EarthCube Research Coordination Network (@HDMIEC RCN), with primary objectives to discuss current advances and identify future needs for the solar research cyberinfrastructure. The white paper summarizes presentations and discussions held during the special working group session at the EarthCube Annual Meeting on June 19th, 2020, as well as community contribution gathered during a series of preceding workshops and subsequent RCN working group sessions. The authors provide examples of the current standing of the solar research cyberinfrastructure, and describe the problems related to current data handling approaches. The list of the top-level recommendations agreed by the authors of the current white paper is presented at the beginning of the paper.
SMD↗
Physical properties of white-light sources in the 2011 February 15 solar flare
White-light flares (WLFs) are observational rarities, making them understudied events. However, optical emission is a significant contribution to flare energy budgets and the emission mechanisms responsible could have important implications for flare models. Using Hinode SOT optical continuum data taken in broadband red, green, and blue filters, we investigate WL emission from the X2.2 flare SOL2011-02-15T01:56:00. We develop a technique to robustly identify enhanced flare pixels and, using a knowledge of the RGB filter transmissions, determined the source color temperature and effective temperature. We investigated two idealized models of WL emission—an optically thick photospheric source, and an optically thin chromospheric slab. Under the optically thick assumption, the color temperature and effective temperature of flare sources in sunspot umbra and penumbra were determined as a function of time and position. Values in the range of 5000-6000 K were found, corresponding to a blackbody temperature increase of a few hundred kelvin. The power emitted in the optical was estimated at ∼10{sup 26} erg s{sup –1}. In some of the WL sources the color and blackbody temperatures are the same within uncertainties, consistent with a blackbody emitter. In other regions this is not the case, suggesting that some other continuum emission process is contributing. An optically thin slab model producing hydrogen recombination radiation is also discussed as a potential source of WL emission; it requires temperatures in the range 5500-25,000 K, and total energies of ∼10{sup 27} erg s{sup –1}.
79 ASTRONOMY AND ASTROPHYSICS↗
The Most Massive White Dwarfs in the Solar Neighborhood
We present an analysis of the most massive white dwarf candidates in the Montreal White Dwarf Database 100 pc sample. We identify 25 objects that would be more massive than 1.3M ⊙ if they had pure H atmospheres and CO cores, including two outliers with unusually high photometric mass estimates near the Chandrasekhar limit. We provide follow-up spectroscopy of these two white dwarfs and show that they are indeed significantly below this limit. We expand our model calculations for CO core white dwarfs up to M = 1.334 M ⊙ , which corresponds to the high-density limit of our equation-of-state tables, ρ = 109 g cm -3 . We find many objects close to this maximum mass of our CO core models. A significant fraction of ultramassive white dwarfs are predicted to form through binary mergers. Merger populations can reveal themselves through their kinematics, magnetism, or rapid rotation rates. We identify four outliers in transverse velocity, four likely magnetic white dwarfs (one of which is also an outlier in transverse velocity), and one with rapid rotation, indicating that at least 8 of the 25 ultramassive white dwarfs in our sample are likely merger products.
79 ASTRONOMY AND ASTROPHYSICS↗
Hydrodynamic Models of Line-Driven Accretion Disk Winds III: Local Ionization Equilibrium
We present time-dependent numerical hydrodynamic models of line-driven accretion disk winds in cataclysmic variable systems and calculate wind mass-loss rates and terminal velocities. The models are 2.5-dimensional, include an energy balance condition with radiative heating and cooling processes, and includes local ionization equilibrium introducing time dependence and spatial dependence on the line radiation force parameters. The radiation field is assumed to originate in an optically thick accretion disk. Wind ion populations are calculated under the assumption that local ionization equilibrium is determined by photoionization and radiative recombination, similar to a photoionized nebula. We find a steady wind flowing from the accretion disk. Radiative heating tends to maintain the temperature in the higher density wind regions near the disk surface, rather than cooling adiabatically. For a disk luminosity L (sub disk) = solar luminosity, white dwarf mass M(sub wd) = 0.6 solar mass, and white dwarf radii R(sub wd) = 0.01 solar radius, we obtain a wind mass-loss rate of M(sub wind) = 4 x 10(exp -12) solar mass yr(exp -1) and a terminal velocity of approximately 3000 km per second. These results confirm the general velocity and density structures found in our earlier constant ionization equilibrium adiabatic CV wind models. Further we establish here 2.5D numerical models that can be extended to QSO/AGN winds where the local ionization equilibrium will play a crucial role in the overall dynamics.
Pereyra, Nicolas Antonio↗
White Earth Community Facilities Solar PV Project (Final Report)
Funded project was for the design, installation, and performance monitoring of 2 - 11.4 kW AC and 1-38.0 kW AC ground-mount solar installations for three tribal community facilities, for a total 60.8 kW AC, including a daycare facility and two community centers. Of in excess of 120 tribal buildings these facilities had showed the best promise for implementing solar, based upon site characteristics, roof loads, roof orientation and building size. The White Earth Nation seeks to move forward proactively to address the following project goals and objectives: 1) Reduction of energy costs, 2) Increasing energy security for Indian Tribes and tribal members, 3) Adding 60.8 KW in renewable energy generation (solar PV), 4) Offsets, reduces coal-fired electric energy demand by 76,397 kWh, 817,448 Source Energy Btu annually, and S) Meets the overall solar PV target set in the FOA.
14 SOLAR ENERGY↗
Flow properties of the solar wind obtained from white light data and a two-fluid model
The flow properties of the solar wind from 1 R(sub s) to 1 AU were obtained using a two fluid model constrained by density and scale height temperatures derived from white light observations, as well as knowledge of the electron temperature in coronal holes. The observations were obtained with the white light coronographs on SPARTAN 201-1 and at Mauna Loa (Hawaii), in a north polar coronal hole from 1.16 to 5.5 R(sub s) on 11 Apr. 1993. By specifying the density, temperature, Alfven wave velocity amplitude and heating function at the coronal base, it was found that the model parameters fit well the constraints of the empirical density profiles and temperatures. The optimal range of the input parameters was found to yield a higher proton temperature than electron temperature in the inner corona. The results indicate that no preferential heating of the protons at larger distances is needed to produce higher proton than electron temperatures at 1 AU, as observed in the high speed solar wind.
Habbal, Shadia Rifai↗
Rapid sintering of TiO{sub 2} photoelectrodes using intense pulsed white light for flexible dye-sensitized solar cells
Intense pulsed white light (IPWL) sintering was carried out at room temperature, which is suitable dye-sensitized solar cells (DSSCs) fabrication process on plastic substrates for the mass production. Five seconds irradiation of IPWL on TiO{sub 2} electrode significantly improves the photocurrent density and power conversion efficiency of DSSCs by more than 110% and 115%, respectively, compared to the DSSCs without IPWL treatment. These improvements were mainly attributed to the enhanced interconnection between the TiO{sub 2} nanoparticles induced by IPWL illumination, which is confirmed by the impedance spectra analysis.
36 MATERIALS SCIENCE↗
AZW-LA-II White Paint on Swift: Lessons Learned from First Time Flying on Spacecraft Radiators
AZ-Tek's AZW-LA-II low solar absorptance white paint was previously flown as a flight experiment, and is being flown as a calorimeter. However it has never been flown as a thermal coating of radiators on an operational spacecraft before. This paint has the lowest solar absorptance among all white paints, and a very small degradation. Its cost is many times more expensive than white paints that have a higher solar absorptance. To meet the thermal requirements of the Swift Burst Alert Telescope (BAT) Detector Array and X-Ray Telescope (XRT) focal plane camera assembly (FPCA) charged coupled device (CCD), AZW-LA-II is used as the thermal coating for the BAT and XRT radiators. This paper presents the lessons learned from flying this low solar absorptance white paint as a thermal coating of radiators on an operational spacecraft for the first time.
Choi, Michael K.↗
EMISSION HEIGHT AND TEMPERATURE DISTRIBUTION OF WHITE-LIGHT EMISSION OBSERVED BY HINODE/SOT FROM THE 2012 JANUARY 27 X-CLASS SOLAR FLARE
White-light emissions were observed from an X1.7 class solar flare on 2012 January 27, using three continuum bands (red, green, and blue) of the Solar Optical Telescope on board the Hinode satellite. This event occurred near the solar limb, and so differences in the locations of the various emissions are consistent with differences in heights above the photosphere of the various emission sources. Under this interpretation, our observations are consistent with the white-light emissions occurring at the lowest levels of where the Ca II H emission occurs. Moreover, the centers of the source regions of the red, green, and blue wavelengths of the white-light emissions are significantly displaced from each other, suggesting that those respective emissions are emanating from progressively lower heights in the solar atmosphere. The temperature distribution was also calculated from the white-light data, and we found the lower-layer emission to have a higher temperature. This indicates that high-energy particles penetrated down to near the photosphere, and deposited heat into the ambient lower layers of the atmosphere.
79 ASTRONOMY AND ASTROPHYSICS↗
Optical counterpart of 2A0311-227
Spectrophotometric observations of the optical counterpart of the X-ray source 2A0311-227 are reported. A 1.3-m telescope associated with a photon-counting spectral scanner was used for observations in the range 4000 to 5800 A. Strong emission features are noted for H I, He II at 4686 A and the C III-N III blend at 4640-4650 A. Analyses of radial velocities show the star to be a spectroscopic binary with a period of 81.04 + or - 0.01 min, while blue and yellow light curves reveal variations in stellar color. Similarities between this binary and AM Herculis are noted and a model of a 1.2-solar mass white dwarf with a 0.2-solar mass companion at a separation of 0.7 solar radii is suggested.
Williams, G.↗
Flow properties of the solar wind obtained from white light data, Ulysses observations and a two-fluid model
Using the empirical constraints provided by observations in the inner corona and in interplanetary space. we derive the flow properties of the solar wind using a two fluid model. Density and scale height temperatures are derived from White Light coronagraph observations on SPARTAN 201-1 and at Mauna Loa, from 1.16 to 5.5 R, in the two polar coronal holes on 11-12 Apr. 1993. Interplanetary measurements of the flow speed and proton mass flux are taken from the Ulysses south polar passage. By comparing the results of the model computations that fit the empirical constraints in the two coronal hole regions, we show how the effects of the line of sight influence the empirical inferences and subsequently the corresponding numerical results.
Habbal, Shadia Rifai↗
Characteristics of the white-light source in the 1981 April 24 solar flare
Observations of the white-light solar flare event of April 24, 1981 are presented. The observations were carried out in the optical, hard X-ray, and radio wavelengths from land-based observatories and from the International Sun-Earth Explorer (ISEE-3) satellite. Time-intensity profiles were derived for three lines of continuum emissions. The derived profiles are interpreted in terms of the energetics of the flare, and the role of energetic electrons in the production of optical continuum emission is examined in detail.
Kane, S. R.↗
Spartan - Space at low-cost
Mission profiles and objectives of the Spartan Shuttle payload are described. Spartan was designed to provide extended observations normally carried out for only a few minutes using sounding rockets. The payload will be placed in co-orbit with the Orbiter by the RMS arm and controlled by a ground-based researcher or by an on-board program. Spartan features minimal battery power, batteries, and control systems and no redundancy. Thermal control is added because the flights last 100-1000 times as long as those on sounding rockets. Data are recorded by an on-board tape recorder and operations are controlled by an on-board microprocessor. Spartan 1 will carry a star-pointer and X-ray detectors for high energy astrophysics experiments. Spartan 2 will gather solar physics data in the form of temperatures of hydrogen gas and ions and electrons. Particle densities will also be monitored and a 43 cm solar telescope will produce UV and white light solar coronagraphs. UV spectroscopy of stars, clouds and galaxies will be performed by the Spartan 3 payload.
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