Safety of Fusion Magnets: Model Experiments to High Current ARCS Propagating Along the Busbars of Large Fusion Magnet Coils

The inductive energy of about 40GJ stored permanently inside the toroidal field (TF) coils of ITER provides a considerable potential of hazard in case of an accident. While for most accidents it could be proved that the damage is limited to the coils themselves, possible high current arcs at the busbars of the TF coils may propagate to and penetrate the cryostat wall. Model arc experiments were setup to understand the propagation and damage potential of such arcs to provide a database for the development and validation of a numerical model as the next step. This work reviews the basic arc propagation and burning modes found so far and introduces new experimental setups and findings.