Impact of a Plasma Disruption on the Magnetic Field Variations and Heat Deposition in the TF Conductor of JT-60SA

During a plasma disruption a complex map of magnetic field variation is generated along the JT-60SA TF conductor. The current variations associated with a symmetric plasma disruption are modeled in JT-60SA, on the basis of a circuit approach. The main components of the circuit model are: the poloidal field coils, the plasma represented by circular filaments, the vacuum vessel, and the stabilizing plates. The disruption induces currents in all elements of the circuit model which produce a variation of the field map. At the location of the TF coil, this field change can be assessed and used for ac losses and stability calculations on the TF conductor. An analysis of the map will allow estimating the field change time constants and investigating which points the JT-60SA TF conductor experience the most severe field variations. Based on a recent multi-constant AC losses model for the JT-60SA TF conductor, an analytical model of stability is presented to describe the temperature increase in the cable after a plasma disruption, taking into account the heat transfer to helium during the power losses deposition. A discussion will be introduced about a possible influence of the synchronous parallel field variations, which may saturate the strand filaments and increase the heat losses dissipation.