Showing papers on "Liquid metal published in 1980"

Characteristics of a gallium liquid metal field emission ion source

Abstract: Discusses the emission of positive ions from liquid metals under the action of high electric fields. High brightness sources are being developed with a variety of applications in mind. The basic principles of such sources are discussed and the design and experimental behaviour of a gallium source are described in detail. Measurements of the current-voltage characteristics of the source, together with the angular distribution of the beam are presented. The current-voltage behaviour is found to be in agreement with the predictions of a simple space charge model. Field ion creation mechanisms require liquid metal emitting features of submicron dimensions and this does not appear to be consistent with space-charge considerations and the best available microscopic observations. This apparent paradox can be resolved if a highly mobile emitting feature is assumed to exist.

Alloys for liquid metal ion sources

Abstract: Alloys suitable for use in liquid metal field ionization ion sources are provided. Such sources include an anode electrode for supporting an ion emitter comprising an alloy in the liquid state. The source further comprises means for generating an ionizing electric field and a reservoir for the liquid metal, ions of which are to be emitted by the source. The alloys are selected from the group consisting of (a) metal-metalloid alloys comprising about 10 to 30 atom percent of at least one metalloid element, the balance at least one transition metal element, (b) early transition-late transition alloys comprising about 30 to 85 atom percent of at least one early transition metal, the balance at least one late transition metal, and (c) Group II alloys comprising about 35 to 80 atom percent of at least one Group II element, the balance at least one metal element. Ions generated in liquid metal ion sources form a high brightness ion beam, which permits focusing a beam of emitted ions to a submicrometer spot. The ions may be used to alter material properties by ion implantation such as to dope semiconductors, to form ohmic contacts, to improve wear and corrosion resistance in metal surfaces and by sputter etching thin films such as metals, dielectrics and semiconductors.

Theory of metal-non-metal transitions in liquid-metal alloys

Abstract: A technique for calculating the physical properties of liquid-alloy systems that undergo metal-insulator transitions as their concentrations are varied is presented. A simple tight-binding model is used, which includes short-range order and charge transfer self-consistently. The technique is used to investigate the liquid Cs-Au alloy system in detail. The variation of chemical order with concentration and temperature is calculated by minimising the free energy. This allows the calculation of the variation of conductivity with concentration and temperature, and the variation of magnetic susceptibility and Knight shift with concentration. The results are compared to existing experimental data and the agreement is found to be good.

Process and device for confining liquid metals by use of an electromagnetic field

Abstract: A device for confining liquid metals comprises a coil which surrounds a jet of liquid metal to be confined and means for causing an alternating current to flow through the coil. These means cause an alternating current to flow through the coil at a frequency which is less than the inverse of the product of the magnetic permeability of the liquid metal, the electrical conductivity of the metal and the square of the radius of the jet of the metal after confinement, in coherent units. The invention applies to the casting of steel, aluminium, copper and alloys thereof.

Heat generation patterns and temperature profiles in electroslag welding

Abstract: A formulation is presented to calculate, in three dimensions, the important process parameters such as the voltage profiles, heat generation patterns and temperature profiles in the slag and metal phases for an electroslag welding system. It is shown that the current is significantly larger for the electroslag welding process than that of the electroslag refining process operating with equivalent slag, electrode and other geometrical variables. Calculations show that the heat generation patterns are highly sensitive to the geometrical location of the electrode in the slag and that a relatively minor error in the alignment of the electrode can cause a major asymmetry in the heat generation pattern. The temperature fields in the slag and the metal phases are calculated in three dimensions and the roles played by various factors on the heat balance are assessed. The computation accounts for the transport of heat from the slag to the metal phase by the liquid metal drops, the energy loss due to electrolysis and the energy required for the heating of the cold slag charge. Using the computed values of the weld rate the possible decrease in the heat input due to a) the decrease of the plate gap and b) the use of multiple electrodes is calculated. The values of heat input obtained from independent experiments are compared with model predictions. Possible effects of imposing an external magnetic field during the welding are examined.

Method and apparatus for producing electrical power and for the simultaneous heating of fluid, utilizing a magnetohydrodynamic generator

Abstract: There is provided a method and an apparatus for producing electrical powernd for the simultaneous heating of fluid by means of a magnetohydrodynamic (MHD) generator The method comprises providing a heating means for heating a mixture of liquid metal and an organic liquid to form a two-phase liquid metal-vapor flow, directing the two-phase liquid metal-vapor through a MHD-generator to generate electricity, condensing the vapor phase from the two-phase liquid metal-vapor to form liquid metal carrying organic liquid droplets, and recycling the metal and organic liquid droplets to be reheated by the heating means The MHD apparatus comprises a closed duct system containing a mixture of liquid metal and an organic liquid, a heating means for heating the mixture in the closed system, a MHD-generator, located along the flow path of a two-phase liquid metal-vapor flow formed by the heated mixture, means for condensing the two-phase flow to form a single phase flow of metal liquid containing organic liquid droplets, and means for propelling the single-phase flow to be reheated by the heating means

Hall Effect in Liquid Metals: Experimental Results

Abstract: The development of quantum mechanics at the beginning of this century gave rise to a well-established and fundamental understanding of crystalline solids. One of the basic facts that simplified the theoretical problem was the fundamental property of the crystal lattice, namely its periodicity. This allowed one of calculate approximate yet realistic solutions of the Schrodinger equation. The theory of non-periodic structures is much more difficult and detailed calculations have not yet been performed on a large scale. Since it was not clear to what extent the periodicity itself was directly responsible for the physical properties of crystals, direct experimental studies of non-periodic structures became of the utmost importance. An intense interest in such studies on metallic materials started about 20 years ago. For several reasons liquid metals proved to be excellent materials for such investigations. Above the normal melting temperature liquid metals are in stable thermodynamic equilibrium. They have well-defined atomic structures and can be studied in the form of alloys as well as pure liquid elements. As most liquid metals are completely miscible their alloys can be studied over the entire concentration range. Because of phase diagram restrictions this is not possible for most crystalline alloy systems. Furthermore samples of any desired quantity can easily be prepared.

Liquid metal-cooled nuclear reactor

Abstract: Integrated nuclear reactor cooled by a liquid metal and incorporating a main vessel sealed in its upper part by a slab, an inner vessel containing the core, the latter resting on a system for the positioning and supply of the core with liquid metal and which is called the support, the latter itself resting on a supporting structure bearing on the bottom of the main vessel of the reactor, wherein it comprises an inner baffle cladding the side wall and bottom of the main vessel and defining with the latter an intermediate space filled with the liquid metal, tubes for supplying a liquid metal to the intermediate space below the bottom of the main vessel and tubes for returning said liquid metal to an auxiliary exchanger in order to remove heat from the intermediate space.

Hydraulic shock absorbers

Abstract: A hydraulic shock absorber of the dash pot kind for use with electrically conducting liquid such as sodium, has magnet means for electro magnetically braking a stream of liquid discharged from the cylinder. The shock absorber finds use in a liquid metal cooled nuclear reactor for arresting control rods.

An apparatus employing the pulse-echo overlap technique for the measurement of sound velocities in liquid metals

Abstract: The technique allows high precision measurements to be made at high frequencies where disadvantages inherent in the use of acoustic delay lines are significantly reduced. It is possible to make absolute measurements of sound velocity at 50 MHz with errors as low as +or-0.01% using the apparatus described. Thermal instability and the quality of acoustic coupling to the liquid metal limit the precision of measurement at high temperatures. Sound velocity measurements for liquid indium in the temperature range 440 to 919K are presented.

Control for liquid plant

Abstract: A temperature control system for liquid plant is comprised of liquid metal, plant members, heaters for heating these liquid metal and the plant members at respective control points, a temperature control unit and a control unit. The plant members include a vessel containing liquid metal, pipe lines through which the liquid metal circulates, and valves. Further, temperature sensors, a level detector for detecting the level of the liquid metal, and a meter for detecting the flow rate of the liquid metal, are mounted to the plant members. Temperature sensors produce output signals relating to the condition parameter of the plant which data is delivered via an interface to the temperature control system and the control unit, as the information at each control point. The control unit previously stores the operating schedule of the plant members and transfers, the input signal relating to the plant condition to the temperature control system, with reference to the temperature control schedule. The temperature control system calculates the input signal relating to the process value on the basis of the control information to decide the control value of which the result is applied to the interface. The interface controls the electrical power to be supplied to the heaters at the respective control points in accordance with the control signal inputted.

Narrow gap collector with integral electromagnetic pump

Abstract: A constant supply of liquid metal for a current collector of an acyclic machine is provided by passing armature current radially through a quantity of liquid metal disposed in an annular pumping channel formed between a compliant braided metal filament brush and the stator ring collector surface. A flow restricting plug causes pressure to develop in the circumferentially flowing liquid metal to maintain a constant film of liquid metal in contact with the rotor collector ring and the brush to complete electrical connection therebetween.

Liquid metal purifier

Abstract: PURPOSE:To provide a compact liquid Na regeneration system for facilitated operation in a device to purify liquid Na for use as cooling material in fast breeder reactor by providing a means to control the quantity of exhaust in the regeneration system. CONSTITUTION:A liquid Na purifier body 3 is connected through valve 21 to a regeneration system consisting of a degassing pot 22, a vapor trap 24, a filter 25, an electric-control type valve 31 between the filter 25 and exhausting system, a pressure gauge 32 to detect pressure in the space above the degassing pot 22. A controller 33 regulates the valve 31 in accordance with the output from the gauge 32 so as to maintain the pressure in the space above the pot 22 at a constant value. This value of pressure is set in advance, through the controller 33, to be slightly higher than the vapor pressure of liquid Na at that temperature. This sufficiently reduces the quantity of Na vapor produced from the degassing pot 22 and smoothly exhausts H2 or other impurity. Thus, the vapor trap 24 can be made compact.

Penetration of molten nickel into sintered titanium carbide hard metals

Abstract: A study was made of some aspects of molten nickel penetration into titanium carbide hard metals. It is shown that, when such a liquid phase migrates through a semiinfinite rod, the variation of the concentration of the binder metal along the length of the rod may be described by a hyperbolic function. The dependence of the thickness of the layer of increased nickel content on time of contact between the specimen and the melt was determined. It is demonstrated that, by employing the method of infiltration of a hard metal with a liquid metal, it is possible to produce parts possessing varying physicomechanical properties.

Analysis of ingot temperature field in continuous casting of copper

Abstract: A mathematical model of the ingot temperature field in the continuous casting of copper and other pure metals is presented. The finite-difference method is applied and the difference equations are derived by the elementary energy balances method. An axially symmetrical two-dimensional temperature field in the cast metal and the die is considered. The model takes into account the creation of a gap between the cast metal and the die and a complex heat transfer in the gap. An experimental verification of the mathematical model shows good agreement between the calculated and measured results. The influence of convection in liquid metal and of some technological parameters on the temperature field and the freezing-front shape are analysed. The possibility of a practical utilization of the formulated mathematical model is discussed.

Metallurgical effects of the weld thermal cycle

Abstract: A number of reactions may take place in the liquid weld metal, firstly in the liquid drop at the electrode tip, secondly during transfer from electrode to weld pool, and thirdly in the weld pool itself. These reactions include: (a) Solution of gas, causing gas-metal reactions or reaction with elements dissolved in the liquid metal. (b) Evolution of gas, causing porosity and/or embrittlement. (c) Reaction with slag or flux.

Electromagnetic conduction-pump for liquid metal

Abstract: An electromagnetic conduction pump for liquid metal, including a part of refractory material; two magnetic circuits each including a horizontal arm embedded in the refractory material, the first having a gap and the other being closed; a rising channel arranged in the refractory material for pumping of the liquid metal passing through the gap in the first magnetic circuit and a closed turn of liquid metal communicating with the rising pumping channel at the place where it passes through the gap. The turn consists of a channel of inverted-U shape the legs of which dip into the bath of metal, one of the legs consisting of a section of the rising channel and the other leg partially interlacing the horizontal arm of the second magnetic circuit.

Modeling of fuel-to-steel heat transfer in core disruptive accidents

Abstract: A mathematical model for direct-contact boiling heat transfer between immiscible fluids was developed and tested experimentally. The model describes heat transfer from a hot fluid bath to an ensemble of droplets of a cooler fluid that boils as it passes through the hot fluid. The mathematical model is based on single bubble correlations for the heat transfer and a drift-flux model for the fluid dynamics. The model yields a volumetric heat transfer coefficient as a function of the initial diameter, velocity and volume fraction of the dispersed component. An experiment was constructed to boil cyclopentane droplets in water. The mathematical and experimental results agreed reasonably well. The results were applied to investigate the possibility of steel vaporization during a hypothetical core disruptive accident in a liquid metal fast breeder reactor. The model predicts that substantial steel vaporization may occur in core disruptive accidents, if the steel reaches its saturation temperature rapidly enough. The potential importance of steel vaporization is dependent on the accident scenario.

Temperature controller of hydrogen detector in cover gas

Abstract: PURPOSE:To improve the reliability in the water leak detection of a fast neutron reactor by controlling the temperature of a metal thin film portion with the use of a liquid metal which effects substantially the same density to the atomic density of the hydrogen per unit volume in cover gas phase. CONSTITUTION:A detector 8 is lined with a metal thin film such as an Ni thin film 14 and further with a container 30 of the Ni film, and a metal 31 which is in a liquid state at a temperature in the vicinity of 500 deg.C, and a heater 20 are interposed between the thin film 14 and a guard 15. The thin film 14 and the container 30 are heated by the liquid metal 31 which is heated by the heater 20 and the temperature of the metal 31 is detected by a thermocouple 22. The metal such as Li, which has a low boiling point and an excellent thermal conductivity and which has substantially the same atomic number as hydrogen for the same volume of the metal in the cover gas phase, is used as the metal to be inserted. As a result, even if there is a high heat source so that the flow rate of Ar gases are fluctuated, no large temperature change of the Ni film takes place. As a result the temperature control of the Ni film can be facilitated so that no error signal is generated for the water leak.

A closed-circuit magnetohydrodynamic (MHD) system for producing electrical power and a method for producing electrical power by means of a magnetohydrodynamic (MHD) generator

Abstract: The production of electrical power by means of magnetohydrodynamic (MHD) generator. A closed duct system (2) is provided containing a mixture of an electrically-conductive liquid, which is preferably liquid metal, and an organic liquid, and heating means, preferably a solar absorber (4), for heating the mixture in the closed system. An MHD-generator (8) is located along the flow path of a two-phase liquid metal-vapour flow formed by the heated mixture. A condensor (10) condenses the two-phase flow to form a single phase flow of metal liquid containing organic liquid droplets. The single-phase flow is pumped, for example by an MHD pump 14, to be reheated by the heating means (4).

Liquid sealed diaphragm type pressure transducer

Abstract: PURPOSE:To prevent occurrence of errors in zero point and span due to the residual bubbles, thermal expansion and contraction at the time of sealing a primary pressure transmission medium by providing a heater capable of controlling the temperature at the outer wall part of the pressure receiving part. CONSTITUTION:The temperature of a pressure receiving part 1 due to a high temperature fluid such as liquid metal sodium of a coolant of an FBR is measured by a thermocouple 15, and a heater 14 extending from the pressure receiving part 1 to the first pressure transmitting medium chanber 5 is fed back and controlled. Consequently, the inner part of the chamber heated by a heater 14 to a high temperature is made vacuous, and impurities such as adsorptive gas and the like are purified. Thereafter, when NaK6 of the primary pressure transmitting medium 6 are sealed in the chamber 5 via an inlet port 10 and an output port 11, bubbles do not remain at the time of sealing of the medium 6, thermal expansion or contraction due to the temperature difference do not occur, and hence a pressure measurement free of zero point and span errors can be performed with a high precision.

Surfaces.the surface properties of liquid metals

Abstract: We briefly review recent theoretical and experimental work on the surfaces of various liquids and liquid mixtures. While there has been much progress in understanding the surface structure and thermodynamic properties of argon-like liquids and molten salts, the surface properties of liquid metals and their alloys are much less understood. We mention the relevance of the studies of other liquids to liquid metal surfaces and describe some outstanding problems in this area.