Abstract: An isotopic heat source is formed using stacks of thin individual layers of a refractory isotopic fuel, preferably thulium oxide, alternating with layers of a low atomic weight diluent, preferably graphite. The graphite serves several functions: to act as a moderator during neutron irradiation, to minimize bremsstrahlung radiation, and to facilitate heat transfer. The fuel stacks are inserted into a heat block, which is encased in a sealed, insulated and shielded structural container. Heat pipes are inserted in the heat block and contain a working fluid. The heat pipe working fluid transfers heat from the heat block to a heat exchanger for power conversion. Single phase gas pressure controls the flow of the working fluid for maximum heat exchange and to provide passive cooling.

Abstract: A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

Abstract: Apparatus and method are provided for conducting electric current to cryogenic electrical equipment devices. A combination of inner and outer tubes together form a plurality of hollow composite tubes housed in a sheath. Top and bottom block mounting means are fitted to hold the composite tubes and are affixed to the ends of the sheath. This combination forms a current lead. The current lead is attached to a cryogenic device housing a fluid coolant which moves through the current lead, cooling the current lead as the fluid travels.

Abstract: A method of forming a porous capillary layer of a metal oxide ceramic material onto a metal oxide ceramic substrate, which comprises covering the surface of the substrate with an aqueous slurry of a powdered mixture comprising the metal oxide of the ceramic substrate, silica and an alkali metal or alkaline-earth metal oxide, the powder mixture having a maximum particle size of about 44 microns, removing excess of slurry, depositing onto the wet surface a layer of granular ceramic material having a particle size of about 250 to about 500 microns, the granular ceramic material being applied in excess relative to the powder of the aqueous slurry to insure that a porous capillary structure will be obtained and causing the slurry to be drawn up between the particles so as to absorb substantially all the slurry, and firing the coated surface at a temperature to effect bonding of the ceramic layer, the powdered constituents of the mixture being proportioned to provide liquid phases at about 200.degree.-300.degree.