Abstract: Apparatus for generating high power microwaves and for radiating the microwave power in the HE.sub.1,1 mode into a confined plasma is disclosed. The apparatus includes a microwave generator and mode converters to convert the generated microwave power into the rectangular HE.sub.1,1 mode. A hermetically sealed rectangular HE.sub.1,1 mode power coupler is used between the plasma and a main waveguide run to seal the main waveguide run and the generator from the plasma. The power coupler comprises an input rectangular HE.sub.1,1 mode waveguide, an output rectangular HE.sub.1,1 mode waveguide and a plurality of dielectric sealed apertures through a common wall between the input and output waveguides. Power absorbed by the power coupler is removed by cooling fluid which is circulated through the common wall between the apertures.

Abstract: A multifilamentary superconducting cable has two parallel spaced-apart guide wires. A first layer of mutually parallel superconducting filaments is woven partially around and between the guide wires in a transposed braid. Likewise, a second layer of mutually parallel superconducting filaments is woven partially around and between the guide wires in a transposed braid. Thus, the two layers overlap each other as the respective layers pass between the guide wires. The two superconducting layers and two guide wires are enclosed in a helical copper duct, with the guide wires being oriented within the duct.

Abstract: A substrate for supporting a ceramic superconductor comprises a metallic base member having a constituent oxide former which establishes an oxide layer on the surface of the substrate. A layer of ceramic superconducting material covers the substrate with the oxide layer between the metallic base member and the ceramic superconductor layer to inhibit the interdiffusion of respective constituent elements between the metallic base member and the ceramic layer. For applications requiring the transmission of electrical current through the ceramic layer over relatively extensive distances, the substrate can be formed as a wire.

Abstract: Dielectric-filled longitudinal slots in the common wall of concentric circular and coaxial dielectric-lined waveguides allow microwave energy to be efficiently coupled therethrough. Such couplers are used with megawatt level gyrotrons for varied applications. One application provides a double seal waveguide vacuum window with low reflections over a wideband of frequencies. Another application provides an output coupler and window for quasi-optical gyrotrons. Still another application provides a waveguide mode converter for converting high order microwave modes, as are commonly found in waveguide cavities of high power gyrotrons, to lower-order modes suitable for low-loss transmission, such as the HE.sub.11 mode.

Abstract: Conversion from a whispering gallery or volume mode to a more useable mode, such as the HE.sub.1,1 mode is achieved in a waveguide mode converter that includes input and output sections. The input section includes overlapping circular and coaxial waveguides. Microwave energy in a whispering gallery or volume mode within the circular waveguide is coupled through an array of N equally spaced axial slots placed in the common wall separating the circular waveguide and the coaxial waveguide to coaxial TE and TM modes. Helical grooves placed in one of walls of the coaxial waveguide convert the coaxial mode to a quasi parallel plate mode wherein the common wall separating the inner circular waveguide from the outer coaxial waveguide functions as one plate, and the outer wall of the coaxial waveguide functions as the other plate. The quasi parallel plate mode propagates microwave energy spirally through the coaxial waveguide in a direction k, where k makes an angle .theta. to the waveguide axis.

Abstract: An apparatus for use in neutron radiography has a convergent collimator of moderator material joined coaxially to a divergent collimator made of neutron-absorbing material. An aperture is formed between the collimators. The divergent collimator substantially defines a neutron beam. An imaging plane is disposed within the neutron beam. The convergent collimator has a base which defines a source plane. Neutron-emitting radioisotopes which are a source of neutrons are placed symmetrically about the source plane. Neutron-moderating material is placed between the neutron sources and the aperture. The convergent-divergent shape of the collimators is designed to expose all of the source plane for optimum and uniform thermal neutron irradiation of the imaging plane.

Abstract: A method and apparatus for cryogenic removal of solid materials includes a wand connected in fluid communication with a cryogen fluid source. The wand directs the cryogen against a selected portion of solid material. The wand has a spray nozzle to direct the spray against an inner exposed surface of energetic material typically contained within a munition casing. The wand is connected to a mounting element to allow movement of the wand within the munition body. The munition is mounted on a rotatable base for rotating the munition and to expose the material to the cryogenic fluid spray. The cyrogenic fluid spray, such as liquid nitrogen, is utilized in a dry washout process to freeze and embrittle the surface layer either by precooling and fluid spray, or by spray alone. The embrittle layer is then eroded away by the spray into small particles for removal by pneumatic transport, vacuum, or other collection and removal system. A mechanism may be provided for vibrating the material to loosen the particles.

Abstract: A superconducting wire and a process for fabricating such a wire. The present invention relates specifically to the fabrication of a wire using a ceramic superconducting material. Initially, a quantity of highly pure high temperature superconducting material is obtained. The superconducting material may be fabricated by any one of a number of known fabrication methods such as by aqueous coprecipitation, conventional sol gel techniques or solid state reaction processes.Once a ceramic superconducting material in particulate form is obtained, surface impurities on the particles are removed. One such surface cleaning procedure is known as "sputtering." Sputtering strips the surface atoms from the surface of the superconducting material, leaving only pure superconducting ceramic.The superconductive ceramic produced according to the procedure outlined above is then used in the formation of a superconducting wire.

Abstract: Synthetic diamond crystals and films are deposited on a pair of uniformly spaced apart facing plates made of silicon, molybdenum or boron in elemental, nitride or carbide form. The plates are suitably supported within a totally thermally insulated chamber where a pressure of about 10 torr or less is maintained in the form of an atmosphere which includes a carbon source and a major portion of hydrogen, and preferably includes oxygen in equal amount to the carbon. By supplying sufficient microwave power to create a plasma and a uniform temperature of about 950.degree. C. at the plate surfaces, diamond crystals economically grow on the surfaces of the facing plates. Preferably, either the plates or the backing sections thereof have a relatively high thermal conductivity so as to maintain a uniform temperature across the entire plate surface areas.

Abstract: The present invention is related to a composition and methods for producing highly pure, high temperature superconducting materials having the general formula MBa.sub.2 Cu.sub.3 O.sub.7-x, where M is yttrium or a rare earth element and x is from 0 to 0.5. The superconducting material is produced by first obtaining a solution of yttrium or rare earth element and copper. Next a solution of barium is obtained. The two solutions are heated and mixed together forming a precursor precipitate of the superconducting material. Subsequently, in one embodiment of the invention, the precipitate is recovered, calcined, sintered and slow cooled in oxygen or air. This produces a material having a desirable orthorhomic structure which is superconductive at high temperatures.Because no organic solvents are used and no pH control other than the amount of barium in the solution is employed, it is possible to provide a highly pure superconducting material.

Abstract: A ceramic superconductor comprises a substantially nonmagnetic preannealed nickel-based alloy substrate which supports a ceramic superconductor. The substrate may include aluminum to strengthen the substrate and make it less magnetic. The substrate is substantially devoid of minority constitutent oxide shell formers and the ceramic is formed on the substrate by sintering superconductor grains at temperatures above 1000.degree. C. to enhance densification of the ceramic.

Abstract: The invention relates to the preparation of high purity, chloride- and alkali metal-free copper (II) alkoxides by means of the reaction of an alcoholic alkali metal alkoxide solution with copper (II) fluoride; ammoniating the resulting solution to render soluble the resulting copper (II) alkoxide; and filtering the resulting solution to obtain an alkali metal- and chloride-free alcoholic copper (II) alkoxide solution. The resulting solution is useful in the preparation of superconducting compound such as yttrium-barium-copper oxide superconductor.

Abstract: Ferromagnetic pieces are mounted on a plurality of nonmagnetic radial rods located at desired locations parallel to a pole face of a permanent magnet used in a magnetic resonance imaging apparatus. The pieces comprise plates which are translatable radially along each rod. Each rod carrying the plates are each rotatable about the rod axis to produce an error field cancelling environmentally induced, low order perturbations. A method for accomplishing same is also included. In a preferred embodiment, the plates are mounted on radial rods positioned at equal angles from one another, preferably thirty degrees (30.degree.) apart and arranged as spokes of a wheel.

Abstract: An electric cable for shielding the conductor therein from tensile stresses during bending of the conductor in a predetermined lateral direction. An elongated duct having a pair of opposed sidewalls and a floor therebetween holds the conductive element, while an elongated lid of relatively substantial thickness is mounted in the opening to the duct between the free ends of the sidewalls. The lid fills the duct from the opening between the free ends of the sidewalls to the neutral surface produced by lateral bending of the cable in the direction of the floor of the duct. Bonding material secures the lid and duct in a fixed longitudinal relationship, and a suitable flowable filler encases the conductor in the resulting tubular housing. The cable disclosed has particular application to the preservation of the integrity of superconductor materials used as the conductor in the cable. Preferably, the duct and lid are made of soft and hard copper, respectively.

Abstract: An adaptor for holding a micropipette in a spectrophotometer includes a base member for holding the micropipette and an optical system for linearly focusing visible or ultraviolet light onto the micropipette. Specifically, the optical system includes a cylindrical lens which focuses collimated light from a light source into a line along the axis of the micropipette. The optical system also includes a cylindrical quartz lens which recollimates the light that has passed through the micropipette sample holder. A detector is provided to receive the recollimated light for measuring the absorptivity of the sample material held in the micropipette.

Abstract: A coaxial microwave absorption diagnostic device comprises a hollow cylindrical outer layer conductor with a coaxially aligned conductor rod extending therethrough and a dielectric material which interconnects the outer layer to the conductor rod. The device is formed with a passageway which is directed perpendicular to the longitudinal axis of the device and which passed through the outer layer, the conductor rod and the dielectric material. As so formed, the passageway is positioned for receiving a sample holder, such as a small capillary tube holding a sample solution. A variable or fixed frequency oscillator is electrically connected to an input end of the conductor rod for sending microwave power through the device and a diode senses the output portion of this microwave power which has passed through the device. The absorbed power, i.e. the input microwave power less the output microwave power, is determined by a comparator and used to analyze the sample.

Abstract: A method for manufacturing a stress controlled wire comprises the step of twisting superconductor fibers together into a bundle of fibers. A plurality of bundles are then twisted together and disposed within the lumen of a tube and the lumen is flooded with solder which is allowed to harden. The tube and its contents are subsequently heated as they are wound upon a drum to melt the solder and allow realignment of the superconductor fibers within the solder. The subsequent solidification of solder after the tube is wound onto the drum provides an unstressed support for the fiber bundles.

Abstract: An apparatus for minimizing hysteresis in a magnetic resonance imaging device of the type utilizing a pair of oppositely charged parallel pole faces forming a magnetic field therebetween, and gradient coils spaced apart from each pole face for producing time varying magnetic fields, comprises a layer of nonferromagnetic conducting material interposed between the pole face and the gradient coil. The interposed layer carries eddy currents induced by time varying magnetic fields produced by the gradient coils, thereby minimizing AC induced eddy current hysteresis from the pole faces. The layer preferably has a thickness of at least one skin depth at the frequency associated with the time varying magnetic field. The layer is preferably contiguous with the pole face, and comprises copper or aluminum. In another embodiment, each pole face has a plurality of slits therethrough radiating inward from the circumference for eliminating the eddy currents in the pole face.

Abstract: Nuclear fuel particles having fission-product-retentive characteristics are disclosed which are particularly adapted for the production of nuclear fuel compacts or nuclear fuel elements by combination with a matrix material having an acceptable nuclear properties and good thermal conductivity. Preferably, the outermost shell of the fission-product-retentive layer is formed of a refractory carbide, such as silicon carbide or zirconium carbide, and a thin overcoating material is applied thereto. When aluminum is employed as the matrix material, an overcoating of elemental silicon or elemental zirconium is used which is wet by the aluminum matrix. Silicon also forms a low melting eutectic alloy with the aluminum of the matrix that provides good lubricating properties--a particularly valuable feature when high pressure extrusion is used to form fuel elements.

Abstract: A system for characterizing contamination levels of a selected site uses a base station for the collection of data and generating waste site characterization and remediation needs reports. An on-site station is provided to detect the contamination levels at selected points within the site and transmit this data to the base station. The on-site station also includes a transceiver which relays information to the base station from the Global Positioning System satellite constellation which pertains to the precise location of the on-site station within the site to be characterized. The base station may also have a specific transceiver which is in communication with the Global Positioning System satellite constellation for determining the precise topographical position of the base station and for correlating this data with the topographical position of the on-site station to refine the latter.