Abstract: A compact multilayer ceramic-to-metal seal structure, and method for manufacture, includes a ceramic core with opposed metallic surface layers. Between the ceramic core and each of the metallic surface layers is a transition zone which is made from graded layers of metallic and ceramic powders. These layers have progressively greater concentrations of metallic constituents than ceramic constituents the nearer the layer is to the metallic surface layer. Conversely, within the transition zone, the nearer a layer is to the ceramic core, the greater is its concentration of ceramic constituents. This seal is manufactured by simultaneously sintering a multilayer structure of compressed ceramic and metallic powders.

Abstract: A magnet system for providing a localized, substantially homogeneous magnetic field for use in nuclear magnetic resonance imaging. The magnet system includes a vacuum vessel defining a bore for receiving the subject of the imaging. It further includes a cryogenic containment vessel supported within the vacuum vessel. A single coil or "simple" solenoid is positioned within the containment vessel for providing the magnetic field. This coil includes a winding made up of thousands of turns of small superconductive wire, with the winding having a modular geometry including a plurality of axially spaced wire modules. The coil further includes an insulative substance, having a greater coefficient of thermal contraction than that of the wire, distributed in the winding. As the temperature of the coil is reduced from room temperature to its cryogenic operating temperature, the development of localized stress concentrations of sufficient magnitude to rupture the wire, are avoided.