Computational Simulations of the Cooling of Type II Superconductors Using a Material Specific Formulation of the Ginzburg Landau Equations

Superconducting Radio Frequency (SRF) cavities play a fundamental role in particle accelerators. Efficient operation depends on expelling magnetic flux from the cavity, and any residual flux that remains trapped after cooling below the critical temperature can have a significant impact on performance. Experimental evidence suggests that cooling protocols can have a strong impact on subsequent performance. To better understand this phenomenon, we use time-dependent Ginzburg-Landau theory implemented as finite-element simulations. We adapt the theory to allow spatial variation of material-specific parameters along with realistic temperature dependencies. We report on numerical experiments for different configurations of pinning sites and cooling protocols and discuss implications for SRF cavity design and operation.