Superconductivity Above H_{c2} as a Probe for Niobium RF-Cavity Surfaces

Sara Casalbuoni, Lars von Sawilski, Jürgen Kötzler

From the magnetic response of Nb-cylinders to time-varying fields the AC-conductivity, ${\sigma }^{\prime }-i{\sigma }^{\prime \prime }$, and the critical current density $J_c^s$ are determined above the upper critical f…