| 摘要 |
PURPOSE:To maintain the degree of vacuum in a rotor for a long period by providing a tube communicating with an adiabatic vacuum tank around a liquid helium filling tube, and mounting the vacuum evacuation port of the tube at a helium supply and exhaust unit to evacuate it. CONSTITUTION:A tube 19 communicating with an adiabatic vacuum tank 4 provided around a field winding 2 is formed around a liquid helium filling tube 14 communicating with a liquid helium reservoir 13 provided in a superconductive field winding 2. A vacuum evacuation port 20 of the tube 19 is formed at a helium supply unit 10. Thus, the tube 19 can be preferably evacuated even if a rotor is not stopped, and cryogenic pumping effect around the tube 14 can be maintained for a long period. Accordingly, the degree of vacuum in the rotor can be maintained for a long period. |
