The Effect of Local Damage Inside a Winding on Quench Behavior in an Nb$_{3}$Sn Magnet

Abstract

Even in small superconducting coils quench can be a severe problem. Sometimes an internal local damage can significantly degrade the performance of a coil. If the damage decreases the local critical current only slightly the coil can still perhaps fulfill the performance requirements due to the stability margin used in the design phase. However, this localized damage can dramatically affect the quench behavior. In addition, during training, premature quenches can arise from arbitrary locations due to e.g. epoxy crack. In this paper the effect of a local damage on the quench characteristics in a conduction-cooled Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn magnet was studied computationally. The location and the grade of the damage were varied. The grade of the damage was modeled as a variation in the local degradation of critical current. The effect of the damage on protection requirements is also discussed.