| 摘要 |
PURPOSE:To prevent a helium case from exploding, by letting the helium gas escape when the pressure in the helium case excessively increases. CONSTITUTION:This equipment is provided with the following; a helium case 45 constituting a liquid helium vessel 50 wherein liquid helium is accommodated in a sealed space, and a superconducting magnet and a permanent current switch are dipped in the liquid helium, and a vacuum case 31 constituting a vacuum vessel 42 which surrounds the helium case 45, forms a sealed space, and vacuumizes the space. The helium case 45 is provided with a safety valve which is opened when the pressure in the helium case 45 reaches a previously set value, and lets the pressure escape into the vacum case 31. When the quenching is generated or heat in the atmosphere permeates into the liquid helium vessel 50, the liquid helium is vaporized and the pressure in the helium case 45 abnormally increases. Since the pressure is let escape into the vacuum case 31, the helium case 45 does not explode. |
