Current and Superconductor
The magnetic field strength of 2 to 5 tesla is perfectly suited for the
use of niobium-titanium superconductor in a copper matrix cable co-extruded
(or plated) with aluminium. This technique of aluminium stabilisation is
applied to handle the large amount of stored energy, to facilitate indirect
cooling and to enhance particle transparency. The superconducting cables
can operate with currents up to many thousands of amperes when cooled down
to 4.8 kelvin (-268 °C).
In total some 206,000 kilograms of conductor is required for the ATLAS
magnet system.
The Barrel Toroid and the two End-Cap Toroids are electrically connected
in series and likewise operated at a current of 20,500 amperes.
The Central Solenoid operates at a nominal current of 7,600 amperes.
As the magnets are made with superconducting cable, the power converters
used to generate these high currents can be operated at a tension below
24 volt. Most of the power loss is in the normal conducting (aluminium and
copper) water cooled bus-bars connecting the power converters to the magnets.
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General