| | The medium field Q-slope for Nb cavities has been studied
in the past as a thermal feedback effect combined
with the nonlinear BCS surface resistance due to currentinduced
RF pair-breaking. We are systematically exploring
the behavior of the medium field Q-slope with various
cavity parameters such as wall thickness, residual resistance,
bath temperature, Kapitza conductance, RF frequency,
RRR, and phonon mean free path. We study cases
involving only the standard (linear) BCS resistance as well
as those including the nonlinear BCS resistance. The systematic
comparison suggests specific experiments to determine
the role of the nonlinear contribution. | |