Showing papers on "Liquid metal published in 1974"

Surface plasmons in liquid mercury: Propagation in a nonuniform transition layer

Abstract: We have examined the propagation of nonradiative surface plasmons in the presence of an inhomogeneous transition zone in the surface region of a conductor. The model we treat in the present paper is the Epstein stratified conductivity profile that has been proposed by Bloch and Rice for liquid mercury. Assuming that photon-plasmon coupling occurs through frustrated total reflection, we evaluate the optical response of mercury to surface-plasmon excitation and find it to be sensitive to the existence of such a zone. Measurements of the dispersion relation should, therefore, provide valuable information regarding the range and degree of such electronic inhomogeneity; preliminary measurements are in good agreement with the theory (Sec. VI). In addition to inhomogeneity in the conductivity of nearly-free electrons in the liquid metal, we have also investigated the effect of the localized resonances near the surface, and we speculate under what conditions the surface-plasmon dispersion relation may exhibit "anomalous dispersion" due to plasmon-localized-state interaction. Finally, the existence of an upper plasmon branch induced by the inhomogeneity is treated. In general, the results of the present investigation suggest that optical surface-plasmon spectroscopy should be a useful technique for the study of nonuniform conducting surfaces.

Electronic effects in dynamical structure of liquid metals

Abstract: The partial dynamical structure factors of a pure liquid metal are derived from the two-component theory developed in an earlier paper by March and Tosi. In particular, and in contrast to the usual procedure which assumes the hydrodynamic form for the ion-ion dynamical structureSii(q, ω) to be the same as for a classical one-component liquid, in the present theory the contribution to the sound-wave attenuation from single-particle excitations in the conduction electron system is derived explicitly. It is suggested that this is closely related to the anomalous scaling with isotopic mass of the atomic transport coefficients in liquid lithium. The relation to neutron elastic scattering is also established, and some measurements on liquid gallium can be interpreted in a qualitative manner. By studying the charge-charge correlation function for the two-component liquid metal, a theory of electrical resistivity is afforded, which is shown to reduce to Baym’s treatment of the scattering of electrons by the density fluctuations in the limit of weak electron-ion interaction. The relation between the high-frequency conductivity, obtained for arbitrary strength of the electron-ion interaction and the classical Drude-Zener theory is pointed out, and the sum rules for conductivity are seen to be related to those forSii(q, ω) in the limitq→0. A brief discussion of the thermodynamics of the two-component system is included, and related to results for weak electron-ion coupling.

Measurement of the differential pressure of liquid metals

Abstract: The flow of liquid metal in a pipe is opposed by a magnetic-type liquid metal pump until there is almost zero flow shown by a magnetic-type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of hightemperature bellows or diaphragm seals, and a magnetic-type liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed.

Drop transfer in short-circuit welding

Abstract: This paper considers the physical processes which may occur when a liquid weld metal drop comes in contact with a liquid metal pool. Experiments with drops of aqueous KCl solutions and mercury, combined with a theoretical analysis of the effects of surface tension and Lorentz forces, lead to the following conclusions. Drops larger than a critical size, which is a function of the capillary constant and wire diameter, will transfer to the pool and smaller drops will lead to stable menisci. Surface tension alone will complete the interaction in approximately k(M/4πT)1/2 s, where M and T are the drop mass and surface tension in CGS units and k similar 37. An electric current I can result in a repulsive force on drops of radius less than approximately μ0I2/16π2T (MKS units). The magnetic pinch instability can dominate surface tension effects under extreme conditions, and magnetically induced streaming can make otherwise stable menisci unstable. Applied to short-circuiting MIG welding systems, these results show how proper attention to the current and weld metal surface tension can lead to reduced spatter and better process control.

Mechanism of volume viscosity in the liquid metal system lead‐bismuth

Abstract: Ultrasonic measurements in the Pb–Bi liquid metal system show that volume viscosity in these alloys differs from that observed in the pure metals Pb and Bi. The excess absorption in the alloys exceeds that in either of the pure metals at low temperatures and decreases with increasing temperature. We suggest that this absorption is due to two effects: (1) a structural volume viscosity similar to that observed in pure Pb and Bi; and (2) a volume viscosity due to concentration fluctuations.

Temperature compensated inductive liquid metal level indicator

Abstract: A liquid level inductance sensor incorporating means for compensating for temperature and non-linearity effects. Instead of using auxiliary temperature sensing devices for compensation, the inductance is made to act as its own temperature sensor. Two signals are derived from the sensor, one for temperature and the other for liquid level. These signals are processed in either digital or analog signal processing techniques to correct for non-linearity and temperature effects.

Nuclear reactor I

Abstract: A nuclear reactor, particularly a liquid-metal breeder reactor whose upper internals include provision for channeling the liquid metal flowing from the core-component assemblies to the outlet plenum in vertical paths in direction generally along the direction of the respective assemblies. The metal is channeled by chimneys, each secured to, and extending from, a grid through whose openings the metal emitted by a plurality of core-component assemblies encompassed by the grid flows. To reduce the stresses resulting from structural interaction, or the transmissive of thermal strains due to large temperature differences in the liquid metal emitted from neighboring core-component assemblies, throughout the chimneys and the other components of the upper internals, the grids and the chimneys are supported from the heat plate and the core barrel by support columns (double portal support) which are secured to the head plate at the top and to a member, which supports the grids and is keyed to the core barrel, at the bottom. In addition to being restrained from lateral flow by the chimneys, the liquid metal is also restrained from flowing laterally by a peripheral seal around the top of the core. This seal limits the flow rate of liquid metal, which may be sharply cooled during a scram, to the outlet nozzles. The chimneys and the grids are formed of a highly-refractory, high corrosion-resistant nickel-chromium-iron alloy which can withstand the stresses produced by temperature differences in the liquid metal. The chimneys are supported by pairs of plates, each pair held together by hollow stubs coaxial with, and encircling, the chimneys. The plates and stubs are a welded structure but, in the interest of economy, are composed of stainless steel which is not weld compatible with the refractory metal. The chimneys and stubs are secured together by shells of another nickel-chromium-iron alloy which is weld compatible with, and is welded to, the stubs and has about the same coefficient of expansion as the highly-refractory, high corrosion-resistant alloy.

Liquid metal cooled fast breeder nuclear reactors

Abstract: A liquid metal fast breeder nuclear reactor of the pool kind. The intermediate heat exchanger depends from the roof of the primary vessel in a housing and is immersed in the reactor coolant. A gas pocket seals the passage between the heat exchanger shell and the housing to prevent liquid metal by-passing the tube bundle.

Suspended nuclear reactor containments with reduced thermal stress

Abstract: A containment for a nuclear reactor has a primary vessel for containing the reactor core and liquid coolant. The primary vessel is suspended by its rim from the roof of the containment structure. To reduce thermal stress at the suspension joint, cooling means is provided for the upper peripheral regions of the primary vessel. The cooling means comprises an annular tank containing liquid metal and heat-exchange coils, thermal insulation of varying thickness and a cooling jacket for the thermal insulation.

Method of producing granules of magnesium and its alloys

Abstract: The method is based on the introduction to liquid metal at the temperature of 670 DEG -720 DEG C of a salt heated to the temperature of 670 DEG -730 DEG C, composed of metal chlorides and fluorides not reducible by magnesium taken separately or in combination, and having an initial crystallization temperature below that of the granulated metal, and a density at the temperature of 670 DEG -730 DEG C equal to 0.95-1.2 of the density of the metal.

Liquid metal core transpactor elements for electromagnetic forming tools

Abstract: Transpactor elements for electromagnetic forming tools comprising elastomeric members surrounding liquid metal cores are disclosed. When the transpactor elements are subjected to an intense varying magnetic field, the liquid metal cores deform. The elastomeric members transmit the deforming force to an associated workpiece causing it to deform into an adjacent die. When the magnetic field is removed, the elastomeric members restore the liquid metal cores to their original configurations. In order to protect the wearing surface of the transpactor elements, a replaceable elastomeric liner is mounted between the elastomeric member and the workpiece. In addition, the transpactor elements may include apparatus for maintaining the temperature of the liquid metal within a predetermined range. In one form, such apparatus cycles the liquid metal between a liquid metal resevoir and the elastomeric member. In an alternate form, such apparatus causes a liquid to flow through the elastomeric member to add heat to or remove heat from the liquid metal.

Activated aluminum and method of preparation thereof

Abstract: Reactive aluminum consisting essentially of aluminum having a purity by weight of at least about 99.99% permeated by a liquid metal selected from mercury, gallium and gallium/indium alloys. The permeation can be accomplished at room temperature and atmospheric conditions. The reactive aluminum exhibits greatly altered physical and chemical properties as compared to the aluminum before permeation. These new properties include a uniform alignment of atomic grain boundaries and domains and a multitude of channels defined in the reactive aluminum.

Pulsed deuterium lithium nuclear reactor

Abstract: A nuclear reactor that burns hydrogen bomb material 6-lithium deuterotritide to helium in successive microexplosions which are ignited electrically and enclosed by this same molten material, and that permits the conversion of the reaction heat into useful electrical power. A specially-constructed high-current pulse machine is discharged via a thermally-preformed highly conducting path through a mass of the molten salt 6 LiD 1-x T x (0

Electrochemical cells having a liquid alkali metal electrode

Abstract: In an electrochemical cell, such as a sodium-sulphur cell, having a liquid metal electrode and a solid electrolyte, capillary means are provided to draw the liquid metal over one face of the electrolyte, so enabling the whole surface of the electrolyte to be in contact with the metal despite reduction in volume of the metal in the anodic compartment. The capillary means may be constituted by a narrow space between the electrolyte and another member, e.g. a housing, or by fibrous or porous material forming a wick.

Energy transport system and method

Abstract: A liquid metal, such as sodium potassium eutectic NaK, is a recycleable fuel which is transported from a generating facility to distributing stations through underground pipelines. The liquid metal within the pipeline transmits electrical power. An adjacent pipeline returns reaction products of the liquid metal in solution to the generating facility for reconversion to liquid metal.

The spin susceptibility of liquid transition metal alloys

Abstract: The theory of Levin, Bass and Bennemann (see abstr. A69754 of 1971 and abstr. A65117 of 1972) for the spin susceptibility of transition metal alloys is generalized to describe the properties of liquid metal alloys. The short range structural order in the liquid alloy is taken into account using a lattice theory with the lattice chosen to match the experimentally measured short range behaviour of the liquids. The theory is applied to the alloy systems Au-Ni and Au-Fe and the results are compared to experimental measurements on these systems, and found to give good agreement.

Theory of phase separation in liquid metal alloys

Abstract: The critical point for phase separation rin liquid alloys of nearly-free-electron metals is determined by two different methods. The first involves a variational approach in which the Helmholtz free energy of the alloy is expressed in terms of hard-sphere structure factors and entropy. The phase boundary is then found by a common tangent construction applied to the free energy isotherms. In the second approach, the long-wavelength concentration fluctuations are calculated within a meanfield approximation. The divergence of these fluctuations is then used as a criterion to determine the critical point. Both methods lead to critical points in satisfactory agreement with experiment in a number of binary alloys, and in addition suggest systematic rela- tions between the phase boundary and such parameters as effective ionic diameters, atomic volumes, and valency differences between the alloy constituents.

Apparatus and method for the production of metal vapor

Abstract: Disclosed is a technique for producing vapors of metals in containment vessels that experience the melting temperature but not the boiling temperature of the metal being vaporized. The metal is maintained in molten pools by the containment vessel. Pumping means such as wicks transfer the metal from the pools to a higher temperature region internal of the containment vessel where the liquid metal is boiled into a vapor. The generation of laser radiation from an excited metal vapor produced in this manner is also disclosed.

Liquid-metal atomization for hot working preforms

Abstract: Rapid quenching of a liquid metal by atomization or splat cooling overcomes the major limitation of most solidification processes, namely, the segregation of alloying elements, impurities, and constituent phases. The cooling rates of different atomizing processes are related to the dendrite arm spacings and to the microstructure of the atomized powders. The increased solubility limits and the formation of metastable compounds in splat-cooled alloys are discussed. Consolidation of the powders by hot isostatic compaction, hot extrusion, or hot forging and rolling processes yields billets with properties equivalent to or better than those of the wrought alloys. The application of this powder processing technology to high-performance alloys is reviewed.

Means for forming metal parts

Abstract: A method for forming metal parts wherein molten liquid metal is injected into a cavity. The cavity is reduced in size compressing the metal. The cavity is cooled, cooling the metal. The metal is held in the cavity until solidified. The cavity is opened for removal of the forming part. Apparatus for forming metal parts comprises a die housing containing a die with apparatus to connect and separate same and to inject molten liquid metal into the die. The liquid molten metal under pressure is held in the die. Same is cooled simultaneously. An apparatus removes the formed part.