Radiation effects in silicon and gallium arsenide solar cells using isotropic and normally incident radiation

Several types of silicon and gallium arsenide solar cells were irradiated with protons with energies between 50 keV and 10 MeV at both normal and isotropic incidence. Damage coefficients for maximum power relative to 10 MeV were derived for these cells for both cases of omni-directional and normal incidence. The damage coefficients for the silicon cells were found to be somewhat lower than those quoted in the Solar Cell Radiation Handbook. These values were used to compute omni-directional damage coefficients suitable for solar cells protected by coverglasses of practical thickness, which in turn were used to compute solar cell degradation in two proton-dominated orbits. In spite of the difference in the low energy proton damage coefficients, the difference between the handbook prediction and the prediction using the newly derived values was negligible. Damage coefficients for GaAs solar cells for short circuit current, open circuit voltage, and maximum power were also computed relative to 10 MeV protons. They were used to predict cell degradation in the same two orbits and in a 5600 nmi orbit. Results show the performance of the GaAs solar cells in these orbits to be superior to that of the Si cells

Optimal traps in graphene

We transform the two-dimensional Dirac-Weyl equation, which governs the charge carriers in graphene, into a non-linear first-order differential equation for scattering phase shift, using the so-called variable phase method. This allows us to utilize the Levinson Theorem to find zero-energy bound states created electrostatically in realistic structures. These confined states are formed at critical potential strengths, which leads to us posit the use of `optimal traps' to combat the chiral tunneling found in graphene, which could be explored experimentally with an artificial network of point charges held above the graphene layer. We also discuss scattering on these states and find the zero angular momentum states create a dominant peak in scattering cross-section as energy tends towards the Dirac point energy, suggesting a dominant contribution to resistivity.Comment: 11 pages, 5 figure

Bryophytes and their distribution in the Blue Mountains region of New South Wales

The bryophytes (mosses, liverworts and hornworts) that occur in the Blue Mountains region of New South Wales (latitude 33˚–34˚ S, longitude 151˚–151˚40’ E) are listed and information is provided on their distribution in the region. Species lists are based on herbarium specimens and field collections. 348 bryophyte taxa have been recorded from 70 families, including 225 moss taxa (in 108 genera from 45 families), 120 liverwort taxa (in 51 genera from 24 families) and 3 hornwort taxa (in 3 genera from one family). The moss families with most taxa are the Pottiaceae (with 23 taxa in 13 genera), Bryaceae (with 15 taxa in 3 genera) and Fissidentaceae (with 13 taxa). The largest genera are Fissidens (13 taxa), Campylopus (9) and Macromitrium (8). The liverwort family with the most taxa is Lepidoziaceae, with 29 taxa in 10 genera. The largest liverwort genera are Frullania (11 taxa) and Riccardia (8). The species lists include collections from both bushland and urban areas. Natural features of the Blue Mountains, including topography, altitude, climate and vegetation appear to be important factors influencing the number of bryophyte species recorded from each location. The number of collections from particular locations has been considerably influenced by ease of access, particularly proximity to roads, public transport and railway stations. The species lists include many records from areas that were not accessible to the early collectors of the late 19th and early 20th centuries such as Wollemi National Park, Gardens of Stone National Park, Newnes Plateau and Kanangra-Boyd National Park

Characterization of solar cells for space applications. Volume 11: Electrical characteristics of 2 ohm-cm, 228 micron wraparound solar cells as a function of intensity, temperature, and irradiation

Parametric characterization data on Spectrolab 2 by 4 cm, 2 ohm/cm, 228 micron thick wraparound cell, a candidate for the Solar Electric Propulsion Mission, are presented. These data consist of the electrical characteristics of the solar cell under a wide range of temperature and illumination intensity combinations of the type encountered in space applications

Characterization of solar cells for space applications. Volume 14: Electrical characteristics of Hughes liquid phase epitaxy gallium arsenide solar cells as a function of intensity, temperature and irradiation

Electrical characteristics of liquid phase epitaxy, P/N gallium aluminum arsenide solar cells are presented in graphical and tabular format as a function of solar illumination intensity and temperature. The solar cells were exposed to 1 MeV electron fluences of, respectively, 0, one hundred trillion, one quadrillion, and ten quadrillion e/sq cm

Charged particle radiation damage in semiconductors, 15 - Study and determination of an optimum design for space utilized lithium doped solar cells, part 1 Interim final report

Hall coefficient measurements of irradiated lithium doped solar cell

Charged particle radiation damage in semiconductors. Part 14 - Study of radiation effects in lithium doped silicon solar cells

Lithium doped silicon solar cells under electron irradiation and determination of semiconductor parameter

Solar cell radiation handbook

The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented

Characterization of solar cells for space applications. Volume 8: Electrical characteristics of Spectrolab BSF, BSR, textured 290-micron solar cells (K7) as a function of intensity, temperature and irradiation

A set of parametric data is presented on the Spectrolab textured, back-surface-field, back-surface-reflector solar cell which is a commercially available product

Characterization of solar cells for space applications. Volume 12: Electrical characteristics of Solarex BSF, 2-ohm-cm, 50-micron solar cells (1978 pilot line) as a function of intensity, temperature, and irradiation

Electrical characteristics of Solarex back-surface-field, 2-ohm-cm, 50-micron N/P silicon solar cells are presented in graphical and tabular format as a function of solar illumination intensity, temperature, and irradiation