Incident Solar Flux Research Articles

Altitude Distributions of and Radiations from Certain Oxygen and Nitrogen Metastable Constituents

The airglow emitted by certain metastable constituents N(2D), O(1D), O+(2P), and O+(2D) in the daytime atmosphere is investigated and their altitude distributions of density are obtained.The production of N(2D) atoms by dissociative recombination of N2+ with electrons is considered. Their quenching by collisions with O2 molecules is calculated, and it was shown that the calculated integrated intensity of NI 5199A line agrees with the observed value.Assuming collisional deactivation of O(1D) atoms by O2 molecules, the production rates of O(1D) by photo-dissociation of O2 in the Schumann-Range continuum at low, medium and high activities of the sun are calculated. The O(1D) distribution and rates of emission of the oxygen red line in the dayglow are also calculated. Calculated intensity at minimum activity agrees with the observed value. An order of magnitude increase in its intensity from minimum to maximum activity cannot be accounted for as due to the variations of molecular oxygen concentration and of solar extreme ultra violet flux incident upon the upper atmosphere. Contributions due to dissociative recombination of O2+ and by thermal electron impact at different levels of solar activity cannot be computed as the variation of ion composition of the ionosphere and that of electron temperature with solar cycle are not known.The production rates of metastable O+(2P) and O+(2D) ions by photoionization of O atoms are calculated. Their equilibrium distributions are computed after using the recent data of rate coefficients for ion-atom interchange and other ionic reactions. As a check, the zenith intensity of (7319-7330A) multiplet of O+ in the day airglow is calculated.

1500. Determination of the simulated solar flux incident on a spacecraft in a test chamber: M Toussaint, Rep ESRO-TM-11, July 1967, 57 pages ( Sci Tech Aerospace Reps, 6 (7), 982, N68-16555)

1500. Determination of the simulated solar flux incident on a spacecraft in a test chamber: M Toussaint, Rep ESRO-TM-11, July 1967, 57 pages ( Sci Tech Aerospace Reps, 6 (7), 982, N68-16555)

On the linear relationship between the Zurich Sunspot Numbers and the incident Solar Radio Radiation Flux at 10.7 cm

The linear relationship between the solar radio radiation flux at 10.7 cm as measured at Ottawa and the Zurich sunspot numbers (Rz) is examined. The linear relationship between daily flux and pot activity has been found inadequate.

Optimization of Contact Grid Spacing for High Solar Flux Photovoltaic Cells

A method for obtaining the optimum gridline spacing for photovoltaic cells operating at high solar fluxes is presented. Using a distributed resistance and diode model of a photovoltaic cell, a differential equation is obtained which relates voltage to position on the cell surface. This equation was solved numerically to obtain the maximum power point efficiency. The maximum power point efficiency is shown to depend upon five dimensionless groups which are combinations of basic cell parameters, geometric parameters, and the solar flux level. The results are presented in graphical form from which the optimum gridline spacing can be obtained for any desired incident solar flux. In addition, the variation in the performance of any specified cell can be obtained from the graphs as a function of the solar flux level.

Model atmospheres of the major planets

view Abstract Citations (177) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Model atmospheres of the major planets Trafton, L. M. Abstract Non-gray model atmospheres have been constructed for the major planets assuming and introducing first-order radiative-equilibrium corrections to account for convection. The thermal opacity was provided by the pressure-induced absorption of HI and also by its enhancement resulting from mixing with He The thermal opacity due to NH3 was found to be negligible in all of the major planets except Jupiter, where the effect is but minor. In constructing the models, the He/H abundance ratios and effective temperatures were considered free parameters to be determined by fitting the models to the observations. In all the models the absorption is strong enough to bring about convection in the deeper layers. In the case of the Jovian models, the amount of HI lying above the convective zone is found to be approximately equal to the observed amount lying above the planet's visual cloud layer. The Jovian limb darkening in the 8-14- region can be explained in terms of absorption due to 113, He, and the 10-i# band of NH1 but cannot be explained when the NH3 band is excluded. Models of Jupiter for which only the thermal opacity of HI and NH3 are taken into account are incompatible with the observations. Adding He, however, eliminates this incompatibility, indicating that He is present in these atmospheres. In the case of Jupiter, a rather large He/H value is implied if there is no internal heat source. However, the observations suggest that the value of He/H is less than 2 so that the existence of a small internal heat source generating more than one-tenth of the incident solar flux is implied. Publication: The Astrophysical Journal Pub Date: February 1967 DOI: 10.1086/149052 Bibcode: 1967ApJ...147..765T full text sources ADS |

Germanium-silicon, lead telluride, and bismuth telluride alloy solar thermoelectric generators for venus and mercury probes

The design, theory, and fabrication of Bi 2Te 3 alloy solar thermoelectric flat plate generators for near-Earth orbit missions has been previously described. [1] This present paper considers the feasibility of extending its application to auxiliary power systems for exploratory missions towards the Sun for the incident solar radiation fluxes from 130 to 1000 W/ft 2. The principal potential advantages of flat plate solar generator technology for these high solar fluxes are increased power-per-unit area, increased power-per-unit weight, increased power-per-unit cost and increased radiation resistance. Design equations and comoputational techniques are discussed which allow approximate solution for the generator output power as a function of distance from launch. Commercially available Bi 2Te 3 alloy, PbTe, and SiGe alloy materials are considered separately though combined systems may offer a greater flexibility of power design for any particular mission. With state-of-the-art thermoelectric materials and emissive coating technology and for the worst case of equal absorber and radiator plate areas, the principal results of these calculations are as follows: For near Mercury and Venus orbits, PbTe has a higher W/ft 2 (21 W/ft 2) than GeSi or Bi 2Te 3 alloy; but GeSi alloy has a higher W/lb of thermoelectric material (1000 W/lb).

Solar Thermoelectric Generators for Missions Toward the Sun

This paper considers the feasibility of extending the application of Bi2Te3 alloy solar thermoelectric flat plate generators to auxiliary power systems for exploratory missions directed toward the sun. The incident solar radiation fluxes would range from 130 to 1000 watts per ft2. The principal potential advantages of flat plate solar generator technology for these high solar fluxes are increased power per unit area, increased power per unit weight, increased power per unit cost, and increased radiation resistance. Design equations and computational techniques are discussed which allow approximate solution of the generator output power as a function of distance from launch. Commercially available Bi2Te3 alloy, PbTe, and Si-Ge alloy materials are considered separately.

Long-term variation of solar extreme ultraviolet fluxes

The aeronomical importance of the 27-day variation of the incident solar EUV fluxes observed from the Oso 1 satellite over two successive solar rotations during spring 1962 has been discussed recently by Bourdeau et al. [1964] in this journal. Existing observational knowledge of variations over longer periods of time is even less satisfactory than that concerning these 27-day variations, since no continuous EUV monitoring experiments were ever made before the launch of Oso 1. Inferences of long-term variations of absolute intensities in the solar EUV spectrum based on a few short-lived rocket experiments must be treated with caution. In this letter we discuss the significance of certain long-term variations which are apparently implied by measurements variously covering the EUV range from 1300 A to 250 A and 310 A to 55 A, accomplished in rocket experiments with EUV monochromators by our group of the Air Force Cambridge Research Laboratories over the past five years. The essential results of these measurements obtained since the first successful monochromator flight of 1959 have been reported previously (except for results from the flight of December 12, 1963, which are presented here). References and data on EUV fluxes up to August 1960 were presented by Hinteregger [1961] and later work was discussed recently by Hinteregger et al. [1965].

Effect of the earth's orbital eccentricity on incident solar flux at 10·7 cm

Effect of the earth's orbital eccentricity on incident solar flux at 10·7 cm

Upper Atmospheres of the Planets.

view Abstract Citations (40) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Upper Atmospheres of the Planets. Chamberlain, Joseph W. Abstract Most of our knowledge of the earth's upper atmosphere is obtained from experiments in sit or remote observations that offer fairly direct interpretations. For the other planets, neither approach is as yet possible; so indirect, theoretical procedures are required to construct models of their atmospheres. Herein the wide variety of basic physical processes governing the structure of a planetary high atmosphere are set forth, with a view toward obtaining "deductive models' `-i e, models derived theoretically when only the chemical composition and temperature of the lower atmosphere and the incident solar flux are specified (in addition to various physical and astronomical constants). The procedures are applied to Mars, whose lower and middle atmosphere is already partially understood from earlier work, notably that of R. Goody. The uncertainties involved at various stages in the construction of such a model are emphasized, as are the major differences in physical processes and atmospheric characteristics between Mars and the earth. The most significant result is that the CO that must be in the upper atmosphere of Mars should serve as an effective thermostat, keeping the temperature at the escape level (1500 km) from exceeding about 11000 K. This is cool enough for Mars to retain atomic oxygen. Were it not for CO cooling, the upper atmosphere of Mars would be so extensive and form such an effective thermal insulation between the upper ionosphere and the heat sink at the mesopause that the temperature would exceed 20000 K. lifetime for the escape of oxygen is estimated as 10 years. The mesopause is determined by CO2 radiation. Near the mesopause CO2 should become dissociated and the free 0 atoms form a thin layer of O this effect has no analogy on earth. The model ionosphere has considerably smaller densities of ionization than comparable regions in the earth's atmosphere The E region is split into two distinct portions, with X-rays forming the higher one (E2) and ultraviolet light ionizing Oi near the mesopause (E1) The Martian analogue to the terrestrial F2 region may not develop a very high electron density, and the entire ionosphere should be depleted at night. Publication: The Astrophysical Journal Pub Date: September 1962 DOI: 10.1086/147409 Bibcode: 1962ApJ...136..582C full text sources ADS |

Temperature and flux vs. geometrical perfection

This paper describes the problems involved in determining the energy flux and temperature existing at the focus of a solar furnace. Theoretical values are readily calculated from the geometry and materials of the system, but actual measurements are much more difficult to obtain. A method is described by which brightness temperature, as measured by an optical pyrometer, and normal incident solar flux, measured simultaneously, can be converted into black-body temperatures.