Recent results of feasibility study to use the high T/sub c/ oxide superconductors for microwave tube magnets

The authors present results of a study to determine the feasibility of using high-T/sub c/ (90 K) ceramic superconductors in place of permanent magnet and conventional solenoids on microwave tubes. In the first phase of this work they developed a strategy based on persistent currents flowing in leadless, jointless configurations. In the present phase they focus on the possibilities and limitations of this design concept associated with the granular properties of the oxide superconductors in bulk ceramic form. They report measurements of the spatial distributions of the supercurrent density, excitation schemes, decay modes, long-term stabilities, and environmental degeneration in prototype ring magnets made from Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/. The prospects for practical microwave tube applications are discussed in the light of RF studies of granular superconductivity in this compound and recent advances in material preparation techniques.<>