[en] Additions of a few parts per thousand of oxygen to a CO-He mixture change drastically the laser output power, the axial field in the positive column, and the slope of the E-I curve of the discharge. The intensity of the spectrum of vibrational transitions of the CO molecule increases when oxygen is added; the increase is especially pronounced for transitions from higher (u greater than 7) levels. The most prominent feature in the visible spectrum is the disappearance of the C₂-Swan bands with the addition of oxygen. The populations of CO vibrational levels were derived from the IR spectra; they increase by more than an order of magnitude for u greater than 7. The electron energy distribution was derived from measured E/N and the Boltzmann equation. Oxygen affects the Boltzmann equation (and thus the electron energy-distribution function) through the change in E/N, which is in turn determined by ionization and deionization processes. The fractional power transfer from electrons increases to vibrational levels and decreases to electronic levels

No abstract available

[en] It is analyzed how small oxygen additions in vanadium carbide affect short-range order. It can be assumed that short-range order in the studied compounds refers to homogeneous type, oxygen introduction into VC_x results in the decrease of the short-range order degree in arrangement of vacancies

No abstract available

[en] The effect of oxygen on thermal expansion, elastic moduli, and thermal diffusivity of Zircaloy-4 nuclear reactor fuel cladding was determined for the main purpose of providing baseline data for LOCA evaluation codes. Measurements were made over the temperature range 298 to 1473 K and 0.7 to 28 at.% oxygen. Expansion and moduli were measured in the two relevant directions, while diffusivity was measured in the principal heat transfer direction (through the clad). Thermal expansion and elastic moduli both increased with oxygen, while diffusivity decreased. Similar measurements were made on Zircaloy-2, but only to 5 at.% oxygen. Differences between the two alloys were within experimental error of the measurements made. (orig.)

No abstract available

[en] The transformation characteristics of rapidly heated (approximately 100-200⁰C/s) and β-quenched zircaloy-4-0 alloys (0.1-1 wt% 0) have been investigated in detail. Analyses of the heating transients showed that the temperatures Tsub(L) and Tsub(u) for the beginning and end of the α→β transformation was not significantly altered by heating rate in the range of approximately 15-200⁰C/s. TEM studies revealed entangled dislocations within martensitic α'plates, with the plate boundaries made up of high density dislocations and precipitates. Internal [1011] twinning was observed only for the 0.13 wt% 0 alloy. The Widmanstatten α plates, however, had their plate boundaries delineated by precipitates and low density dislocation walls. The plate interior contained small angle subboundaries and polygonized networks. The plate width W alone was sufficient to characterize the cooling rate. (Auth.)

[en] In a study of neutron-irradiated Mo containing voids, Schultz et al. [Phys. Rev. Lett. 44, 1629 (1980)] presented data which showed a small fraction of positronium atoms being formed in the voids and decaying by three photons. This effect was observable at temperatures above roughly-equal650 K. It was stated at that time that the positronium may be forming through the same type of high-temperature positron desorption mechanism that had previously been observed for various metallic surfaces with the use of low-energy positron beams. In this Brief Report we show that the temperature at which thermal positronium is activated from a clean Mo(110) surface is 1000 K, which decreases significantly with adsorbed oxygen contamination. These results are consistent with the previous conclusions if the Mo voids were covered with oxygen

[en] A process is described for obtaining oxygen doped zinc telluride monocrystals, for use as scintillator crystals for ionising radiation detectors. The following operations are carried out in succession: one or several zinc telluride crystals are introduced into a silica ampoule together with a ternary mixture of zinc tellurium and oxygen, as an oxide or hydroxide of these elements; the ampoule is pumped down to a high vacuum and sealed; the sealed ampoule containing the mixture and monocrystals is placed in a kiln and brought to a uniform temperature sufficient to make the mixture three-phased, depending on its composition; the zinc telluride crystalline compound remains solid; the ampoule is then tempered to bring it quickly back to ambient temperature

[en] The method has been developed for determining oxygen content in molybdenum and tungsten usign the neutron activation analysis. The sensitivity is 1.6X10^-5 and 1.3x10^-3 wt.% for molybdenum and tungsten, respectively. The density of oxygen distribution in surface layers has been experimentally evaluated. It is shown that the oxygen presence in a surface layer of molybdenum and tungsten does not impede oxygen determination in the bulk of the sample, when the oxygen content is >5x10^-5 wt.%. If oxygen content is <2.10^-3 wt.%, the presence of oxygen in the surface layer should be taken into account