Superconductor Simulation — Type-II, Critical State & AC Losses
Bean critical state model, E-J power law for Type-II superconductors, HTS tape modeling, AC losses in coils, and quench analysis in superconducting magnets.
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Quick Explainer
What makes superconductor simulation fundamentally different from regular magnetics FEM?
Conventional conductors obey Ohm's law: J = sigma*E. Type-II superconductors have a highly nonlinear E-J relationship modeled as E = Ec*(J/Jc)^n with n=20-50. This extreme nonlinearity means flux penetrates according to the Bean critical state model — very different from skin-effect eddy currents. The nonlinearity makes convergence challenging.
What are AC losses in superconducting coils and why do they matter cryogenically?
Although DC resistance is zero, AC losses occur due to magnetic flux motion in Type-II superconductors. Even milliwatts of loss in LHC magnets or MRI coils are significant because cryogenic cooling efficiency is very low — 1W of cooling at 4K requires roughly 300W of electrical input. Minimizing AC losses drives the geometry of Rutherford cables and HTS tape stack designs.