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Transistorized power switch and base drive circuit therefore

Description: A high power switching circuit is disclosed which utilizes a four-terminal Darlington transistor block to improve switching speed, particularly in rapid turn-off. Two independent reverse drive currents are utilized during turn-off in order to expel the minority carriers of the Darlington pair at their own charge sweep-out rate. The reverse drive current may be provided by a current transformer, the secondary of which is tapped to the base terminal of the power stage of the Darlington block. In one application, the switching circuit is used in each power switching element in a chopper-inverter drive of an electric vehicle propulsion system.
Date: March 24, 1981
Creator: Lee, F.C. & Carter, R.A.
Partner: UNT Libraries Government Documents Department

Method and apparatus for the formation of a spheromak plasma

Description: An inductive method and apparatus for forming detached spheromak plasma using a thin-walled metal toroidal ring are described that uses external current leads and internal poloidal and toroidal field coils located inside a vacuum chamber filled with low density hydrogen gas and an external axial field generating coil. The presence of a current in the poloidal field coils, and an externally generated axial field sets up the initial poloidal field configuration in which the field is strongest toward the major axis of the toroid. The internal toroidal-field-generating coil is then pulsed on, ionizing the gas and inducing poloidal current and toroidal magnetic field into the plasma region in the sleeve exterior to and adjacent to the ring and causing the plasma to expand away from the ring and toward the major axis. Next the current in the poloidal field coils in the ring is reversed. This induces toroidal current into the plasma and causes the poloidal magnetic field lines to reconnect. The reconnection continues until substantially all of the plasma is formed in a separated spheromak configuration held in equilibrium by the initial external field.
Date: March 24, 1981
Creator: Jardin, S.C.; Yamada, M.; Furth, H.P. & Okabayashi, M.
Partner: UNT Libraries Government Documents Department

Neutron-detection apparatus

Description: An atomic fission counting apparatus used for neutron detection is provided with spirally curved electrode plates uniformly spaced apart in a circular array and coated with fissile material.
Date: April 24, 1981
Creator: Kopp, M.K. & Valentine, K.H.
Partner: UNT Libraries Government Documents Department

Separator assembly for use in spent-nuclear-fuel shipping cask. [Patent application]

Description: A separator assembly for use in a spent-nuclear-fuel shipping cask has a honeycomb-type wall structure defining parallel cavities for holding nuclear fuel assemblies. Tubes formed of an effective neutron-absorbing material are embedded in the wall structure around each of the cavities and provide neutron flux traps when filled with water.
Date: April 24, 1981
Creator: Bucholz, J.A.
Partner: UNT Libraries Government Documents Department

Improved method of preparing composite superconducting wire

Description: An improved method of preparing composite multifilament superconducting wire of Nb/sub 3/Sn in a copper matrix which eliminates the necessity of coating the drawn wire with tin is described. A generalized cylindrical billet of an alloy of copper containing at least 15 weight percent niobium, present in the copper as discrete, randomly distributed and oriented dendritic-shaped particles, is provided with at least one longitudinal opening which is filled with tin to form a composite drawing rod. The drawing rod is then drawn to form a ductile composite multifilament wire containing a filament of tin. The ductile wire containing the tin can then be wound into magnet coils or other devices before heating to diffuse the tin through the wire to react with the niobium forming Nb/sub 3/Sn. Also described is an improved method for making large billets of the copper-niobium alloy by consumable-arc casting.
Date: April 24, 1981
Creator: Verhoeven, J.D.; Gibson, E.D.; Finnemore, D.K.; Ostenson, J.E.; Schmidt, F.A. & Owen, C.V.
Partner: UNT Libraries Government Documents Department

Method for producing nuclear fuel

Description: Nuclear fuel is made by contacting an aqueous solution containing an actinide salt with an aqueous solution containing ammonium hydroxide, ammonium oxalate, or oxalic acid in an amount that will react with a fraction of the actinide salt to form a precipitate consisting of the hydroxide or oxalate of the actinide. A slurry consisting of the precipitate and solution containing the unreacted actinide salt is formed into drops which are gelled, calcined, and pressed to form pellets.
Date: April 24, 1981
Creator: Haas, P.A.
Partner: UNT Libraries Government Documents Department

Method for fabricating a seal between a ceramic and a metal alloy

Description: A method of fabricating a seal between a ceramic and an alloy comprising the steps of prefiring the alloy in an atmosphere with a very low partial pressure of oxygen, firing the assembled alloy and ceramic in air, and gradually cooling the fired assembly to avoid the formation of thermal stress in the ceramic. The method forms a bond between the alloy and the ceramic capable of withstanding the environment of a pressurized water reactor and suitable for use in an electrical conductivity sensitive liquid level transducer.
Date: July 24, 1981
Creator: Kelsey, P.V. Jr. & Siegel, W.T.
Partner: UNT Libraries Government Documents Department

Power recovery system for coal-liquefaction process. [Patent application]

Description: Method and apparatus for minimizing energy required to inject reactant such as coal-oil slurry into a reaction vessel, using high pressure effluent from the latter to displace the reactant from a containment vessel into the reaction vessel with assistance of low pressure pump. Effluent is degassed in the containment vessel, and a heel of the degassed effluent is maintained between incoming effluent and reactant in the containment vessel.
Date: April 24, 1981
Creator: Horton, J.R.
Partner: UNT Libraries Government Documents Department

Coal gasification apparatus. [Patent application]

Description: Coal hydrogenation vessel has hydrogen heating passages extending vertically through its wall and opening into its interior.
Date: April 24, 1981
Creator: Nagy, C.K.
Partner: UNT Libraries Government Documents Department