Theoretical Investigation of the Absorptive Properties of Small Particles and Heavy-Atom Gases

Technical Report · Thu Sep 01 04:00:00 EDT 1966

DOI:https://doi.org/10.2172/4469946· OSTI ID:4469946

Krascella, N. L. ^[1]

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1. United Aircraft Research Laboratories, East Hartford, CT (United States)

A theoretical investigation was conducted to determine the spectral and mean absorption characteristics of solid and gaseous elemental materials which might be utilized to control the transfer of radiant energy in the propellant region of a gaseous nuclear rocket engine. Spectral extinction, absorption and scattering parameters were calculated, based on the Mie theory, for spherical molybdenum, niobium, tantalum and cadmium particles having radii of 0.01, 0.05, 0.10, and 0.50μ. Similar calculations were made for spherical tungsten particles at five temperatures between 1600 K (2880 R) and 2400 K (4320 R). The tungsten calculations were based on analytically extrapolated refractive indices for wavelengths between 0.1 and 30μ at each temperature. The Rosseland mean absorption parameter of spherical tungsten particles having a radius of 0.05μ was calculated for temperatures between 1000 K (1800 R) and 5600 K (10,080 R). In addition, the spectral absorption parameters and normal spectral reflectivities of bulk aluminum, cadmium, carbon, cobalt, hafnium, iridium, iron, molybdenum, niobium, nickel, palladium, platinum, silicon, tantalum, thallium, titanium, tungsten, vanadium, and zirconium were calculated. The bulk absorption parameters apply to seeds in the form of thin plates and are generally higher than those for seeds in the form of spherical particles. Average reflectivities for normally incident radiation, determined by weighting the normal spectral reflectivities with respect to the black-body radiation function, were computed for aluminum, copper, gold, nickel, silver and tungsten. The spectral absorption coefficients and Rosseland mean opacity of gaseous tungsten were re-evaluated using the UARL heavy-atom model with a modified oscillator strength distribution function. Additional average local line spacing and local line intensities for materials which might be used as gaseous seed agents were calculated. These materials included neutral iron, silicon, uranium, and vanadium as well as singly ionized niobium, tungsten, and vanadium.

• Research Organization: United Aircraft Research Laboratories, East Hartford, CT (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); US Atomic Energy Commission (AEC)
• NSA Number: NSA-21-000604
• OSTI ID: 4469946
• Report Number(s): NP--16338; E-910092-7
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
ALUMINUM
CADMIUM
CARBON
COBALT
COPPER
GASES
GOLD
HAFNIUM
IRIDIUM
IRON
MOLYBDENUM
NICKEL
NIOBIUM
NUMERICALS
PALLADIUM
PARTICLES
PLATES
PLATINUM
PROPULSION
REACTORS
REFLECTORS
ROCKETS
SCATTERING
SILICON
SILVER
SPECTRA
SPHERES
TANTALUM
THALLIUM
TITANIUM
TUNGSTEN
URANIUM
VANADIUM
ZIRCONIUM