Cooling magnets to −270°C and controlling voltage at power plants

[menniandscience]

1. how do they cool the (huge) magnets at CERN to -270 celsius degrees?
2. how a power planet can increse or decresse the electric potential difference (voltage)?
tthanksl

 

[Bob S]

1. See this thesis on the design of a small liquid helium refrigerator:
http://minds.wisconsin.edu/handle/1793/7604
See also
http://cdsweb.cern.ch/record/795005/files/lhc-project-report-796.pdf
This from the LHC Design Report has more detail:
https://edms.cern.ch/file/445856/5/Vol_1_Chapter_11.pdf
2. Increase feedback to the rotor (inductively coupled armature) in an alternator (18 to 24 pole) spinning at constant RPM (to maintain constant 50 or 60 Hz).
Bob S