Showing papers on "Shields published in 1972"

Sinter pallet apparatus

Abstract: Sinter pallet apparatus including a frame supporting a plurality of coextensive grate bars formed with relatively thick structural support bodies which are spaced apart to define air passages therebetween. Relatively thin heat shields are arranged over the respective bars and spacers are provided for spacing such shields from such bars to form a heat insulator space between such bodies and shields. Insulating air is disposed in the insulator space and retainer means is included for retaining the shields on the bars.

High-Efficiency High-Temperature Radiation Heat Shields

Abstract: A new configuration for high-temperature heat shielding has been developed and tested; the shields are several times as efficient as those in common use. The configuration consists of a multiturn, close-spaced spiral, wound out of thin tantalum sheet. Conduction losses around the spiral are negligible. Turn-to-turn spacings down to about 100 μm are maintained using low loss spacers; the conduction loss of the spacers sets the limit on the design. A theory is presented for the design of vacuum heat shielding; fundamental limits are considered. Two applications are a mass spectrometer Knudsen cell generating a neutral carbon atomic beam at 2400 K using a total input power of only 165 W, and a high-temperature direct-vaporization ion source generating a 10−6-A gallium beam with a total input power of only 110 W. An attractive future application might be large high-temperature ovens, where large amounts of power have previously been required.

Superconducting shields for magnetic flux exclusion and field shaping.

Abstract: Superconducting shields provide a means of obtainas they undergo a superconducting transition, some ing arbitrarily reduced magnetic fields over considerable flux will invariably remain trapped in the metal. These volumesfor use in diverse applications. Various shieldregions of flux remain pinned in the superconductor ing techniques for high and low flux densities are sureither by non-superconducting impurities or by specific veyed and some recent results discussed. In particular, states of the lattice of the superconductor. In a sense, the flux shielding properties of laminates of Nb3Sn have it is the perfect conductivity of the material which been studied in fields up to 2.5 T. Measurements are makes complete elimination of the trapped flux so difpresented on the shielding efficiency of the laminate as ficult. Of course, the number of pinning sites can be a function of the number of lamellae, the properties of reduced considerably by using very pure, strain-free overlap regions, and the methods of construction. The materials, but the shields then become very difficult to practical application of these devices is illustrated. make and rather delicate to handle.

An analytical and experimental evaluation of shadow shields and their support members

Abstract: For long-duration interplanetary missions involving cryogenic propellants, it becomes necessary to reduce the heat flux into propellant tanks to extremely low values. Radiation is a significant mode of heat transfer in space. Two forms of radiation barriers which effectively reduce radiant heat transfer are multilayer insulation, which consists of many closely spaced, highly reflective layers separated by low-conducting spacers, and shadow shields, consisting of few layers but spaced farther apart to allow heat to escape to the surrounding space. Studies have shown that if the major radiant heat load is unidirectional, such as for a sun-oriented spacecraft, shadow shields can provide performance superior to multilayer insulation.

The ORNL-SNAP shielding program

Abstract: The effort in the ORNL-SNAP shielding program is directed toward the development and verification of computer codes using numerical solutions to the transport equation for the design of optimized radiation shields for SNAP power systems. A brief discussion is given for the major areas of the SNAP shielding program, which are cross-section development, transport code development, and integral experiments. Detailed results are presented for the integral experiments utilizing the TSF-SNAP reactor. Calculated results are compared with experiments for neutron and gamma-ray spectra from the bare reactor and as transmitted through slab shields.