Transient behaviour of a resistive joint in the ATLAS toroids during the magnet ramp-up and discharge

Several resistive joints are foreseen inside the coils of the ATLAS Barrel Toroid. Here we investigate the problems linked to nonstationary effects: during the magnet charge and dump discharge the magnetic field induces eddy-currents inside the joints, increasing the Joule dissipation and possibly exceeding the conductor's critical current. We have developed an electrical model of the joint to predict the current distribution under nonstationary conditions and consequent heat dissipation; this model allowed us to compute the optimum length of these joints in order to minimise the heat dissipation and the eddy-currents. (5 refs).