JPS6428904A - Superconducting magnet device - Google Patents

Abstract

PURPOSE:To cool legs of a container of helium which are hard to cool not only from the inside of the container but also from lower ends, to shorten a cooling duration and to reduce a thermal stress by a method wherein a circulation passage of a coolant is formed inside of heat-insulating support legs. CONSTITUTION:Heat-insulating support legs 7 which are installed between lower parts of legs 2a of a container of helium and a bottom face of a vacuum container 4 are composed of, e.g., fiberglass-reinforced plastic (FRP) pipes; liquid nitrogen, low-temperature gas helium or the like inside a circulation pipe 8 for a coolant from the outside of the vacuum container 4 is supplied to the inside of the pipes; the coolant is guided to the outside of the vacuum container 4 through the circulation pipe 8. The arbitrary low-temperature gas helium during a preliminary cooling stage is fed through an injection pipe 5; it cools a coil 1 and the container of helium 2 sufficiently. If the liquid nitrogen or the low-temperature gas helium which is supplied from the circulation pipe 8 for the coolant is fed to the inside of the heat-insulating support legs 7, the legs 2a of the container of helium which are hard to cool are cooled from lower ends. By this setup, a cooling duration can be shortened; if a flow rate at both legs is controlled, a thermal stress can be reduced considerably.