| 摘要 |
<p>PURPOSE:To heat and evaporate liquid nitrogen injected for precooling, and to shorten labour hour required for precooling by mounting a heater on the bottom of an inner tank for a cryostat. CONSTITUTION:A heater 13 is installed on the bottom 12 of an inner tank 10 for a cryostat 3. Liquid nitrogen 6 is injected in order to precool a superconducting magnet 7. The superconducting magnet is dipped 14 in liquid nitrogen and the heater 13 is conducted, and liquid nitrogen 14 is heated and gasified. The inner tank 10 is decompressed by a vacuum pump 9, residual nitrogen is discharged by vapor pressure, and lastly the inside of the inner tank 10 is filled with helium gas 20, thus completing precooling work. A series of operation of solenoid valves 17, 18, 23, 24, the vacuum pump 9, the heater 13, etc. can be automated by using a controller 22 in said precooling work, thus saving considerable time and labor.</p> |
