Study of the Damage Mechanisms and Limits of Superconducting Magnet Components due to Beam Impact

The energy stored in the particle beams of an accelerator such as CERNs Large Hadron Collider (LHC) is substantial and requires a complex machine protection system to protect the equipment from damage. Despite efficient beam absorbers, several failure modes can lead to beam impact on superconducting magnets. The energy deposition from these beam losses can cause significant temperature rise and mechanical stress in the magnet coils, which can lead to a degradation of the insulation strength and critical current of the superconducting cables. An improved understanding of the damage mechanisms is important for the LHC when considering its planned increase in beam brightness, as well as for other accelerators using superconducting magnets. In this thesis, for the first time the damage mechanisms and limits of Nb-Ti and Nb3Sn superconducting magnet components are studied experimentally at room temperature. Several experiments have been performed to study the effect of heating over different time scales - hours, several seconds and tens of milliseconds - on the polyimide insulation of superconducting magnets and on superconducting multi- lament strands. The set-up of the different experiments are presented, results are discussed and first conclusions on the damage mechanisms and limits of the superconducting magnets are drawn.