Safety of fusion magnets: Pressure impact on arcing in model experiments to high-current arcs propagating along the busbars of large fusion magnet coils

The paper reports the results of the latest experiments to support the development and validation of the numerical model for high-current arcs at the power cables (busbars) to the toroidal field (TF) coils. The busbar arcs have significant potential of danger in case of an accident due to the huge inductive energy of about 40 GJ stored permanently inside the TF coils. In a worst case these arcs may propagate to and penetrate the cryostat wall. The experiments were set up to understand the propagation and damage potential of such arcs. The present work investigates the influence of residual pressure on arcing.