Pathway to a Post Processing Increase in Q0 of SRF Cavities

A significant improvement of the quality factor Q0 from values of 1.5x1010 to values around 3x1010 at 1.8 K has been repeatedly achieved in a fully dressed and horizontally operated TESLA type SRF cavity by thermal cycling, i.e. heating the cavity briefly above the 9.2 K transition temperature of niobium and subsequent cooling. Conceivable explanations for this effect reach from (a) changes in shielding efficacy of the magnetic shielding to (b) thermal currents to (c) hydrogen diffusion. Our experiments suggest that neither (a) nor (c) are responsible for the changes in quality factor. It appears that the dynamics on frozen flux at the transition temperature is responsible for the observed effect. The pathway to this finding is being presented and the application to SRF systems is elicited.