SELF-MAGNETIC FIELDS OF ELECTRON-BEAMS CONFINED TO BORES OF HIGH-T-C SINTERED SUPERCONDUCTING PIPES

High-critical-temperature (T-c) bismuth-based sintered superconducting pipes (Supertrons) confined the self-magnetic fields of single pulsed intense electron beams (similar to 340 keV, similar to 1kA, similar t o 10 ns), similar to 200 G at 90 K, to their bores. The pipes had inne r diameters of 20 and I? mm and walls 1.5 and 3 mm thick, respectively , with a funnel-type entrance with a total axial length of 55 mm. The thick pipe confined higher fields than did the thin one, but the confi ned fields for the thick pipe were less than twice those for the thin one. The confinement of the fields and resultant focusing of the elect ron beams are ascribable to viscous diffusion of the fields through su perconducting walls at a velocity of similar to 10(4) mis. The confine d fields and diffusion velocities will be used as criteria for applyin g the superconductor to high-frequency devices.