Design, Manufacture, and Test of the ATLAS Magnet System Run Down Units

The ATLAS Experiment at the LHC (CERN) has a Magnet System composed by one Barrel Toroid (BT) and two End Cap Toroids (ECT's) powered in series at 20.5 kA with an overall stored energy of 1.5 GJ, and one Central Solenoid, operated at 7,600 A with a stored energy of 39 MJ. During the normal discharge the stored energy is dissipated inside external resistors and diodes (globally referred as Run Down Unit, RDU). Being critical for magnet safety the RDU was designed so as to operate also in case of severe fault conditions. This paper presents the details of the design and the tests performed to develop each component and to assess their behavior under normal and fault conditions. The final test for commissioning inside ATLAS underground cavern are in progress