Disruption Design Criteria for Joint European Torus In-Vessel Components

In view of the modification to the Joint European Torus (JET) plasma facing components foreseen for the 2004 shutdown, the disruption design criteria for in-vessel components have been updated building on the operational experience with divertor plasmas gained since the early 1990s. In fast disruptions the largest contribution to the electromechanical loads comes from currents induced by the poloidal field change. This is proportional to the plasma current decay rate, the maximum of which is observed to be linear with the predisruption plasma current, as if the current quench in the fastest events has a fixed duration, around 10 ms. Usually vertical displacement events (VDEs) take place on a longer timescale. In these cases halo currents determine the worst loading condition. Analysis of recent VDE data confirmed the previously observed magnitude of asymmetries: toroidal peaking factor times ratio of average poloidal halo to initial plasma current up to 0.42.

Experimental evidence to justify the new criteria and procedures for applying them to JET are included. The revised design criteria are discussed and compared with those used for the components already present in the JET vessel.