| 摘要 |
<p>A sleeve assembly (42) for reducing the thermal conduction heat load from the bellows penetration tube (14) to the helium vessel (4) of a superconducting magnet assembly. The sleeve assembly is designed to force helium boil-off gas to flow in intimate contact with the bellows convolutions. The helium boil-off gas thereby intercepts or removes a portion of the heat that would normally be conducted from the bellows convolutions to the helium vessel. The sleeve assembly consists of a circular cylindrical rolled tube (44) made of laminated thermosetting material. The outer diameter of the tube (44) is wrapped with tape in a helical pattern. The diameter of the sleeve and the thickness of the tape wrapping are selected so that the outer circumferential surface of the helically wrapped tape abuts the inner diameter of the bellows (14). The sleeve is fabricated with a relatively small thickness to minimize thermal conduction load. The successive turns of the helical strip of tape are separated by a helical channel which forms a helical flow path for the helium boil-off gas as it flows toward the boil-off gas outlet. As the helium gas spirals around the sleeve assembly, the gas cools the bellows convolutions and the sleeve instrumentation wiring, thereby minimizing thermal conduction losses. Also, the gas will travel inside the bellows convolutions to minimize helium gas conduction inside the convolutions. <IMAGE></p> |
