Solar constant

About: Solar constant is a research topic. Over the lifetime, 967 publications have been published within this topic receiving 29647 citations.

Selection of solar simulator for solar dynamic ground test

Abstract: The 2 kWe Solar Dynamic (SD) Ground Test Demonstration (GTD) experiment will be conducted in 1995 at NASA Lewis Research Center (LeRC). This solar dynamic power system test will be conducted in a simulated space environment and will require an artificial sun. To address the solar simulator requirements for the GTD, Arnold Engineering Development Center (AEDC) was hired under contract to review and visit four existing solar simulator facilities. The four facilities included, AEDC's Mark 1 Chamber, NASA-JSC Chamber A, AEDC's 12V Chamber, and NASA-JPL Space Simulator Chamber. Two design concepts were considered following several months of evaluating existing solar simulator facilities throughout the United States. To satisfy system requirements for the SD GTD experiment the solar simulator needs to provide a uniform light flux to the SD concentrator, provide the light within a subtense angle of one degree, and provide an intensity of one solar constant (1.37 kW/sq m) at airmass zero. Most solar simulators are designed for supplying heat loads to spacecraft where a cone angle as large as 3 degrees is acceptable. It was also concluded that a solar simulator, such like these considered in the AEDC study, would require major facility modifications for NASA LeRC and result in significant impacts to the program. The advanced solar simulator concept developed by NASA LeRC will meet the system requirements for the SD GTD experiment Since SD GTD solar simulator requirements could not be addressed by existing simulator, an advanced concept was considered.

Effects of Electron Irradiation on N on P Silicon Solar Cells

Abstract: Radiation tests on bare N/P silicon solar cells and solar cells with various cover materials were performed with 1 Mev energy electrons for integrated fluxes up to 1016 e/cm2. The effect of electron irradiation upon the physical, electrical, optical, and thermal characteristics of the cells were analyzed and are presented in parametric form wherever practical. In particular, the changes with electron flux in the electrical output, and the temperature coefficients of the electrical output as well as the effect of the angle of incident radiation upon the output, have been investigated. The variations of spectral transmittance of cover materials and the spectral reflectance at angles of incidence between zero and 75 degrees were measured and the data compared to the electrical measurement results. The solar absorptance as a function of angle of incidence and the hemispherical emittance were calculated. All electrical measurements were performed under illumination closely approximating the spectrum of solar irradiation in outer space, and at the intensity of the solar constant. This is of particular importance when studying the effects of charged particle radiation, since the data thus obtained can be directly utilized for spacecraft solar array design.

A lunar surface effective solar irradiance real-time model

Abstract: Information about solar irradiance on the lunar surface is the key to understanding lunar-surface temperature distribution. In this study, we have constructed a lunar-surface effective solar irradiance real-time model in terms of the relationship between solar irradiance and solar constant, solar radiation incidence angle and the Sun-Moon distance. The theoretical erroneous percentage of this model is less than 0.28% during 100 years from 1950 to 2050. These indicate that the model can accurately reflect the variation of effective solar irradiance on the lunar surface. The result showed that the total solar irradiance on the lunar surface would change from 1321.5 to 1416.6 W·m~ -2 in 2007. And the average is 1368.0 W·m~ -2 . We also validated the possibility of existing polar day and polar night at the lunar poles by analyzing the result of solar radiation incidence angle.

Linear-array apertures for in-flight dynamic solar calibration of radiometric channels for Earth radiation-budget applications.

Abstract: The zero-frequency gain of nonimaging radiometers used in Earth radiation-budget applications is usually verified by a procedure that allows the instrument to view the Sun through an appropriate attenuating aperture and then equates its response to the known attenuated solar constant. However, channel intercomparison often requires that data from a low-resolution, relatively slow instrument such as an active-cavity radiometer be compared with data from a high-resolution, fast instrument such as a scanning thermistor–bolometer radiometer. In such a case, consideration of the difference in the dynamic responses of the two channels may be important. A novel technique for in-flight measurement of the radiometric transfer function of such instruments is described and then demonstrated through the use of a high-order dynamic model of the total, wide-field-of-view, nonscanning channel of NASA’s Earth Radiation Budget Experiment (ERBE).

A synthetic method of solar spectrum based on LED

Abstract: A synthetic method of solar spectrum which based on the spectral characteristics of the solar spectrum and LED, and the principle of arbitrary spectral synthesis was studied by using 14 kinds of LED with different central wavelengths.The LED and solar spectrum data were selected by Origin Software firstly, then calculated the total number of LED for each center band by the transformation relation between brightness and illumination and Least Squares Curve Fit in Matlab.Finally, the spectrum curve of AM1.5 standard solar spectrum was obtained. The results met the technical indexes of the solar spectrum matching with ±20% and the solar constant with >0.5.