Abstract
The helium refrigeration system for the 45kG saddle shaped superconducting magnet of 12 tons was installed in the Electrotechnical Laboratory, Then we have succeeded in continuous long-run operation of the system in Oct. 1969. The system is helium closed loop and proto-type of a practical cooling system for a large superconducting magnet. This completely system was certified such as short cooling down time of a heavy magnet, supply of large quantity of liquid helium and trouble free operation with recovery gas. Operation results are as follows:
(1) Cooling down time to 15°K was 50 hours.
(2) Total amount of supplied liquid helium during the test run was 6, 000 liters.
(3) Helium gas was recovered and reused without any losses.
