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Academic Training Lecture Regular Programme
Commissioning of the LHC super-conducting magnets systems - The challenges for getting the nominal cryogenic conditions. (2/4)
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Europe/Zurich
500/1-001 - Main Auditorium (CERN)
Description
The cooling of the LHC is produced by eight large cryogenic plants – one per sector - installed in five cryogenic islands. Each plant is able to produce up to 600 kW at 80 K, up to an equivalent capacity of 18 kW at 4.5 K as well as up to 2.4 kW at 1.8 K. After cooling the huge sector mass of 4.6x106 kg from room temperature down to 1.9 K and filling the magnet with up to 15 tons of helium mainly in superfluid state, the cryogenic system must be tuned without current to obtain stable operating conditions over long period. Following this tuning, powering tests with current ramping and de-ramping, fast current discharges and resistive transitions are performed. Fast discharges of the current of the main magnet circuits dissipate up to 3 kJ per meter in the magnet cold-masses which must remain cooled in superfluid helium. Resistive transitions of magnets create fast pressure and temperature rises and flow surges. Following a resistive transition of a magnet cell (107 m), the recovery time to nominal conditions should not exceed few hours.
Organised by
Daniele Lajust
