Validating the Physics-Driven Lumped-Element Model of the LHC Main Dipole Magnet

Measuring the complex impedance of a superconducting magnet as a function of frequency provides valuable insight into its electrodynamics. In particular, the characteristic features of some non-conform behaviour, such as an insulation fault, may be easier to assess when performing impedance measurements rather than observing time-domain signals. A physics-driven equivalent circuit model of a superconducting magnet has been recently developed, whose parameters are derived using solely measured geometric and material properties. This contribution describes its validation against impedance measurements of a spare LHC superconducting main dipole, performed at the CERN magnet test facility. The proposed model includes lumped-elements capturing individual physical phenomena, such as superconducting filament magnetization, inter-filament and inter-strand coupling currents, eddy currents in the strand copper matrix and various magnet components, and stray capacitances. It is possible to predict the impact of different physical effects in different frequency ranges and compare simulations to experimental results. It is shown that the validated model can accurately reproduce the magnet's impedance in a frequency range up to 5 kHz in the different conditions considered.