[en] Within the framework of basic research on the flow and transport processes in separation nozzles for enrichment of the U-235 uranium isotope absorption measurements were performed with a tunable CO²-laser in a slit-shaped opposed-jet nozzle system operated with a model gas mixture consisting of perfluoromethyl cyclohexane (C⁷F¹⁴) and helium. The results of the density measurements suggest to conclude that, in conformity with earlier measurements made with free molecular probes, disturbances occur in the equilibrium of the translational motions of the mixture components. Accordingly, the heavy component is accelerated at a slower rate in the expansion zone of nozzle flow and in the compression zone it is decelerated less quickly than the light auxiliary gas. From the measurements of the C⁷F¹⁴ band temperature in the flow it can be concluded that there are pronounced disturbances in the distributions of energy between the translational motion and the internal degrees of freedom of this component. These non-equilibrium effects of the energy of the internal degrees of freedom detected here get manifest above all by the reduction of the 10.25 μm band temperature in the zone of C⁷F¹⁴ partial density rise, i. e. in the zone of stagnation of the opposed-jets and they appear also in the flow of pure C⁷F¹⁴, independent of the presence of a light auxiliary gas. (orig./HP)

[en] An improvement is proposed of methods for the separation of isotopes from gaseous compounds by selective excitation with the aid of radiation (laser or natural light source), where the separating effect is increased by taking full advantage of an intensive broad-band radiation spectrum and achieving a high density of molecules. This is achieved by selecting isotopes with a shifting of band edges in their absorption spectra because of the isotopic effect and by applying a frequency range for the exciting radiation containing frequencies exclusively exciting the desired isotope in a fully selective way. As an example, the separation of ²³⁸U and ²³⁵U from UF₆ is mentioned. (UWI)

[en] The diffusion model developed in this paper describes the separation of the uranium isotopes as a transient process where the isotopes, with different relaxation times, tend towards their equilibrium distributions in the centrifugal field of flow. For the transient process the UF₆ velocity ratio constitutes a quantity of special importance determining the steady distribution of the isotopes in equilibrium of pressure and concentration diffusion as well as the relaxation time of the transient process. (orig.)

[en] By stepwise application of structure material a homogeneous separation-nozzle body is formed. Previously partial irradiation and partial removal of mold material is carried out (mask technique). Thick layers and a high aspect ratio may be achieved by means of soft X-radiation. As material for the molds e.g. PMMA is suited. The method may be applied with good technical and economic success if for the mold material an electric nonconductor is used and for the nozzle material, the base plate and the terminal plates an electric conductor. The molds are filled galvanically. (DG)

[en] In the separation nozzle process, uranium isotope separation is based on the mass dependence of the centrifugal forces in a fast curved flow consisting of uranium hexafluoride and a light auxiliary gas that is admixed in a high molar excess. The objectives of this investigation are to determine the dependence of the separating characteristics of a centrifugal flow field on its spatial structure. Calculations were carried out for small UF₆ mole fractions in the light auxiliary gas, so that the complicated ternary diffusion equations are reduced to two simple binary diffusion equations. The calculations show that isotope separation increases with the radial displacement of the UF₆ streamlines relative to the auxiliary gas. Favorable initial distributions for a large radial shifting of UF₆ exist when the flux, at the beginning of deflection, is high for small deflection radii, whereas at the end of deflection, the UF₆ should be concentrated at large radii near the outer deflection wall. Consequently, a radial decrease of flow velocity, a high ratio of nozzle width to deflection radius, and high centrifugal fields at the end of deflection yield high separation effects. Taking into account the interdependence between the gas flow rate, the viscous losses, and the diffusion coefficient, the model developed can predict the influence of geometric parameters on the separating characteristics of the nozzle

[en] A method for producing a component of a separation element for separating a gaseous mixture into fractions is claimed. The element is composed of separating nozzle structures presenting passages defining mixture supply channels, separating chambers and fraction discharge channels. A negative mold of the component is formed by providing a plate of an electrically non-conductive material, whose ability to be removed from the plate is influenced by application of selected radiation. Portions of the plate are irradiated in a pattern corresponding to the passage presented by the nozzle structure to an extent such that material outside of the regions delimiting the passages is removable more easily than material within those regions. The plate of the electrically non-conductive material is mounted on a substrate of an electrically conductive material either before or after irradiation. Material is removed from the plate to create the negative mold of the component. The openings are electrochemically filled with a metal to create a sold plate-shaped member and the negative mold is removed

No abstract available

No abstract available

[en] Beams of microparticles of condensed matter in high vacuum, called cluster beams, are obtained from nozzle sources for molecular beam generation which are used under conditions where condensation occurs in the rapidly expanding nozzle flow. The paper reports on experiments with ⁴He clusters containing 6.5 x 10⁶ atoms, on the average, as measured by a special version of time-of-flight mass spectrometry. While other kinds of clusters tend strongly to solidify due to evaporation cooling helium clusters remain liquid but probably reach temperatures below the lambda-point of bulk liquid ⁴He. In search of properties distinguishing helium clusters from, e.g., neon or nitrogen clusters the scattering of cesium atoms from these clusters is studied using crossed molecular beam time-of-flight techniques. (Auth.)

No abstract available