American Magnetics AMI Superconducting Magnets - Manual (Page 18)

17
Operation
Deenergizing the magnet
current level differences may cause the programmer/ power supply system to
interpret the equalizing voltage as a magnet quench.
Deenergizing the magnet
Ramp the magnet current to zero using the programmer/ power supply system.
When the current in the magnet and the voltage across the magnet reaches zero, the
magnet is de-energized.
System shutdown
1. After the magnet has been de-energized, any desired instrumentation and the
programmer/ power supply system may be shutdown.
2. Prior to disconnecting cables from the dewar top plate, make sure the
programmer/ power supply system and axillary instrumentation are de-
energized.
Warning
Superconducting magnets have the capability to store large amounts of energy
and can be dangerous and potentially fatal. Make sure the magnet is
completely discharged and all electronics are de-energized before performing
any disassembly.
Exercise caution when handling materials which are at cryogenic
temperatures. Severe burns could result to unprotected skin.
Caution
Use care in handling cold cabling, sensors, etc., since these items usually
become very brittle at LHe temperatures and may be damaged if not handled
carefully.
3. To minimize condensation internal to the dewar when allowing the magnet to
warm-up, close all openings except the outlet of the vapor-cooled current
leads (which should have helium gas traps).
4. Warm helium gas may be pumped in to speed up the process. More openings
may need to be provided if gas outflow becomes to large.
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