Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.







Spectral Properties of Gaseous Uranium Hexafluoride at High Temperature


Book Description

A study to determine relative spectral emission and spectral absorption data for UF6-argon mixtures at elevated temperatures is discussed. These spectral data are required to assist in the theoretical analysis of radiation transport in the nuclear fuel-buffer gas region of a plasma core reactor. Relative emission measurements were made for UF6-argon mixtures over a range of temperatures from 650 to 1900 K and in the wavelength range from 600 to 5000 nanometers. All emission results were determined for a total pressure of 1.0 atm. Uranium hexafluoride partial pressures varied from about 3.5 to 12.7 mm Hg. Absorption measurements were attempted at 600, 625, 650 and 675 nanometers for a temperature of 1000 K. The uranium partial pressure for these determinations was 25 mm Hg. The results exhibit appreciable emission for hot UF6-argon mixtures at wavelengths between 600 and 1800 nanometers and no measurable absorption. The equipment used to evaluate the spectral properties of the UF6-argon mixtures included a plasma torch-optical plenum assembly, the monochromator, and the UF6 transfer system. Each is described. Krascella, N. L. Unspecified Center NASA-CR-3244, R79-912869-1 NAS1-14329










Binary Fluorides


Book Description

Coverage For some time, we have contemplated a comprehensive review of the structures and force fields of the binary fluorides. This bibliography of 1498 references marks the first step of that effort. We are pub lishing this material now rather than waiting until the review is complete some two years hence because we believe that the information already accumulated will be of immediate use to a broad spectrum of researchers. Anyone ambitious enough to read through all the articles on binary fluorides will find that the struc tures and force fields of many of these molecules are at present unknown. For example, it has not been clearly established to which point group(s) the lanthanide trifluorides should be assigned. There remain interesting problems relating to the role of Jahn-Teller and pseudo-Jahn-Teller distortions in some of the transition metal fluorides such as VF , MoF , ReF , and ReF , to name only a few. One s s 6 7 also finds fascinating examples of large-amplitude motions, or pseudorotations, as they are often called, in such molecules as XeF 6, I F 7, and PF 5' For those binary fluorides whose equilibrium geometries are precisely known, there still exists the problem of accurately determining the harmonic force field. In a few cases, most notably the Group VA trifluorides, there has been some attempt made at extracting the cubic and quartic contributions to the force field.