PROBLEM TO BE SOLVED: To provide a zero boil-off helium cooling type superconducting magnet, including a pressure controller for generating an exact control signal for controlling the pressure of a helium container.SOLUTION: A superconducting magnet assembly 10 is provided with a pressure container 4 for housing liquid refrigerating agent 46 for making a magnet coil to an extremely low temperature, vacuum container 2 arranged in the surrounding of the pressure container to be separated from the pressure container, cryocooler 12, re-condenser 39 arranged in the space between the pressure container 4 and the vacuum container 2 are thermally connected with the cryocooler 12 for returning a refrigerating agent gas generated from the pressure container 4 to liquid, means 54 and 58 for returning the recondensed liquid refrigerating agent to the pressure container 4, and pressure control means 74 for control the pressure in the pressure container 4 to be made higher than the outside pressure of the pressure container 4. Then, the pressure control means 74 senses the temperature of a recondenser 39, in response to a temperature sensor 70 arranged outside the pressure container 4.COPYRIGHT: (C)1999,JPO【課題】 ヘリウム容器内の圧力を制御する正確な制御信号を発生する圧力制御装置を含むゼロ・ボイルオフ・ヘリウム冷却式超伝導磁石を提供する。【解決手段】 超伝導磁石集成体(10)は、磁石コイルを極低温にする液体冷凍剤(46)を収容する圧力容器(4)と、圧力容器を取囲み且つ圧力容器から隔たる真空容器(2)と、クライオクーラ(12)と、圧力容器と真空容器との間の空間に配置され、クライオクーラに熱接続されて、圧力容器から発生する冷凍剤ガスを液体に戻す再凝縮器(39)と、再凝縮した液体冷凍剤を圧力容器に戻す手段(54、58)と、圧力容器内の圧力を圧力容器の外側の圧力より高くなるように制御する圧力制御手段(74)とを有し、前記圧力制御手段が、圧力容器の外側に配置された温度センサ(70)に応答して前記再凝縮器の温度を感知することを特徴とする。
