On the effect of strand damage on the operating margin of a Nb3Sn Rutherford cable

• The current sharing from a damaged strand of Rutherford-cored cable is to its only two adjacent strands. This phenomenon takes place in any operating condition, such as steady state or transient distribution. most overloaded carries nearly 70 % I c , be compared about 50 nominal all cases. quench advances an accelerated cascade single quenches. characteristic times and lengths associated localized damage are typical diffusion phenomena. Degradation performance superconducting magnets can major concern when brittle material like Nb 3 Sn employed. Indeed, degradation significantly alter the transport properties if, e.g. excessive stress applied during coil magnet manufacturing. In this paper, we study limiting case Rutherford type that, at given location, does not carry current. We refer simplistically ‘broken strand’, regardless actual cause disrupting carrying capability. To aim, model was developed using code THEA, describe electric thermal HL-LHC 11 T dipole magnet. First, studied distribution cable, considering uniform each boundaries, namely with strands behaving generators, zero-resistance joints, equipotential boundaries. concluded that broken play significant role out strand. A similar situation found suddenly goes normal, i.e. it then derived for redistribution instantaneous breakage. detail procedure extract quantities simulation results, demonstrate good agreement between numerically analytical calculation previous theoretical work. results help shed light on repercussions materials . subject indeed crucial next generation accelerator coils high-energy physics projects.