| 摘要 |
A stratified heavy-current cryotron (see Division H1) is produced by depositing alternate layers of a superconductor and an insulator on an insulating substrate. In a first embodiment, Fig. 1 (not shown), a substrate (3), provided with a cooler (2), has alternate layers of lead and lacquer deposited on to its surface from evaporator (8) and atomizer (7). During the spraying of the lacquer layers the ends of the substrate are covered by electro-magnetically controlled masks (5) so that the ends of the lead layers contact one another. A plurality of substrates may be simultaneously treated, or may be mounted on an endless band, a chain, or a revolving conveyer and passed through a number of chambers. In a second embodiment, Fig. 2 (not shown) the substrate is in the form of a tape wound spirally round a drum (14) which is surrounded by chambers (16), (17), (18), (22), (24), (25) separated by airlocks (15). Radiant heaters (20) and cooling tubes (19) are located inside drum (14) opposite chamber (18) and chambers (16), (24), (17) and (22) respectively. Lead is deposited on the tape in chamber (16), magnesium is deposited on to the lead layer in chamber (17) and the magnesium is oxidized in chamber (18). The drum is stepped one third of a revolution between operations, chambers (24) and (25) serving to mask parts of the tape so that the lead layers are divided into sections the ends of each of which are not covered by the oxidized magnesium. In chamber (22) a hard superconductor is deposited across the ends of adjacent sections to maintain the thickness of the strip and to provide connection areas. The drum may also be rotated continuously to produce long strips. The superconductor may also be niobium, vanadium, tantalum, tin or indium or alloys of lead, tin and indium. The insulating layer may be of aluminium oxide or silicon oxide or may be produced by chemical conversion of the surface of the superconductor into an insulator. |
