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Materials studies in support of liquid metal MHD systems

Description: From 14th symposium on engineering aspects of magnetohydrodynamics; Tullahoma, Tennessee, USA (8 Apr 1974). Materials suitable for use in the construction of a high-temperature liquid-metal MHD demonstration generator are identified. The alkali metals, in particular sodium and lithium, are attractive for use as the conductive fluid because of high realizable conversion efficiencies; they are, however, extremely corrosive, particularly at elevated temperatures. The most severe materials problem to be resolved is that of insulator compatibility with the molten alkali metals. Preliminary screening studies of candidate ceramic insulators are qualitatively discussed in terms of generator design requirements. (auth)
Date: January 1, 1974
Creator: Tuohig, W.D.; Roberts, J.T.A. & Singh, R.N.
Partner: UNT Libraries Government Documents Department

Experimental results on the two-stage, Venetian Blind, direct energy converter

Description: Some preliminary results obtained from experiments designed to test the feasibility of the Venetian Blind, direct energy-conversion concept are discussed. A two-stage unit was built and tested and found to have an overall efficiency of 65% for an energy spread of from 330 to 1000 eV. The calculated efficiency was 69% leaving a 4% discrepancy. This discrepancy seems to result from the slight transparency in the backward direction of the ribbons of the converter. (auth)
Date: February 1, 1974
Creator: Moir, R. W. & Barr, W. L.
Partner: UNT Libraries Government Documents Department

Voltage holding considerations for direct-collection units

Description: Results have been obtained from initial experiments designed to study high-voltage breakdown under conditions of importance to the design of direct- collection units. A coaxial configuration was used to mock-up critical fields near grid wires. With appropriate heat conditioning, fields as high as 9.6 x 10/ sup 5/ V/cm were maintained at the surface of a 7-mil-diam tungsten wire. This represents an enhanced field of ~10/sup 8/V/cm at whisker'' sites. Breakdown criteria are proposed for three regimes; initial, field-emission, and ultimate, which differ by the amount of prior conditioning applied to the wire. Additional considerations of importance to direct collectors such as the effect of thermionic emission and ion bombardment are discussed. (auth)
Date: December 1, 1973
Creator: Miley, G.H.
Partner: UNT Libraries Government Documents Department

Design studies of mirror machine reactors

Description: An overview is presented of a mirror fusion reactor design study. The general methodology used in the study is discussed, the reactor is described, and some design alternatives to the present approach are enumerated. The system chosen for this design study is a mirror machine with direct conversion using D- T fuel. The nominal power output is 200 MW. The coil geometry is the Yin Yang, minimum B with a vacuum mirror ratio of 3. The coil is of particular utility because of its simple conductor shapes and because the two separate conductors, by proper B-field biasing, allow the charged particles to escape preferentially through one mirror only and through a relatively small window'' of that mirror. This is necessary for direct converter economy. (auth)
Date: December 1, 1973
Creator: Werner, R.W.; Carlson, G.A.; Hovingh, J.; Lee, J.D. & Peterson, M.A.
Partner: UNT Libraries Government Documents Department

Shallow Solar Pond scheme. Performance assessment of a model system

Description: The division of energy among the various competing processes is discussed in the sequence from the collection of the solar flux, to the production of electrical power at a busbar output'' for the Shallow Solar Pond scheme. The solar collector utilizes shallow flowing water to transfer thermal energy to a hot water reservoir (at approximates 95 deg C). Several layers of plastic sheet cover the collection area to suppress heat losses. A Rankine Cycle thermodynamic system converts part of the heat energy to shaft work and thence to electricity. It would utilize a Freon gas turbine, along with evaporator, condenser and pressurizing pump; the rejected heat would be removed by an evaporation pond (at approximates 25 deg C). The fiducial system used for this analysis is assumed to have an area of 1 km/sup 2/. It would figuratively deliver an output of 81/2 MW; its mean efficiency for the reference input is 2.8%. The reference operating point corresponds to equinoctial noon, 33 deg N lat. (No attempt was made to include a summer- winter optimization). The various losses and power expenses are summarized, (MCW)
Date: October 29, 1973
Creator: Wouters, L. F.
Partner: UNT Libraries Government Documents Department

Practical aspects of fundamental research in thermionic conversion. Progress report, July 1, 1972--August 31, 1973

Description: During the reporting period a system was constructed for testing advanced cylindrical cesium-vapor thermionic converters with indirectly heated emitters. Initial testing of a cylindrical diode with a platinum-clad niobium emitter in pure cesium vapor showed that pulse enhancement could not be obtained with forward pulses as in previous inert gas planar diodes, but the expected enhancement was obtained for reverse pulses. During testing, the arc drop in the unpulsed igtited mode of this converter gradually disappeared. This highly favorable result is tentatively thought to have occurred due to a new type of discharge occurring in a cavity formed by movement of the platinum cladding. A demountable cesium vapor system was also constructed for expanding the exploration of advanced converter configurations previously performed in at inert gas system. A preliminary evaluation of thermionic topping of large electric power plants was performed to illustrate the significance of advanced converter performance in a reoriented general thermionic conversion program. A summary of basic electrode requirements for advanced converter operation is also included. (auth)
Date: January 1, 1973
Creator: Rasor, N.S. & Britt, E.J.
Partner: UNT Libraries Government Documents Department

Surface requirements for electrostatic direct energy converters

Description: From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argonne, Illinois, USA (10 Jan 1974). There are two major electrostatic direct energy converter concepts whlch will be discussed from the point of view of the surfaces. One is the Venetian blind concept and the other is the periodic electrostatic focusing concept. They are both of the direct collector type. Fluxes of D/sup +/, T/sup +/, He/sup ++/, electrons, and x-rays are given. Design consideration due to thermionic emission, secondary electron emission, and radiation cooling are discussed. A detailed discussion is devoted to breakdown physics, the voltages and electric field strengths that can be employed, and how surface deterioration may affect voltage holding due to He/sup ++/ bombardment blistering. (auth)
Date: January 17, 1974
Creator: Moir, R.W.; Barr, W.L. & Miley, G.H.
Partner: UNT Libraries Government Documents Department

Test of fusible insulation for a proposed isotope power unit

Description: In support of the Isotope Kilowatt Program, an evaluation test of the full-scale simulated thermoelectric power generation system was made. The test was run with 6.5 in. of fusible insulation around the heat block-shield to determine the system heat losses. A loss of 10% of full power was obtained with the system operation at a heat block-shield surface temperature of 1100 deg F and an argon pressure of 1.0 psig. A test was run to determine the thermal coupling between the heat block-shield and 12 heat pipes with 12 simulated thermoelectric generators. A heat pipe condenser temperature of 1040 deg F was obtained at a heat block-shield surface temperature of 1150 deg F at a total power input of 34 kW. A loss-of-coolant accident test was made to determine the maximum fuel capsule surface temperature reached during a meltdown of the fusible insulation. The meltdown results yielded a maximum fuel capsule surface temperature of 2175 deg F and an equilibrium temperature of 2070 deg F. (auth)
Date: April 1, 1974
Creator: Lackey, M.E.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of III-V compound thermoelectric materials directed toward segmented silicon--germanium III-V compound advanced nuclear power systems. Topical report for the period September 1, 1965--February 28, 1966

Description: Declassified 30 Aug 1973. Progress on the couple design, testing and reliability, optimization of material fabrication, and advanced technology is reported. (TFD)
Date: March 31, 1966
Partner: UNT Libraries Government Documents Department