Performance Enhancement of Medium-Temperature Baked Niobium SRF Cavity by Surface Contamination Removal

Medium temperature (mid-T) baking, typically conducted at 300 350 C, enhances the quality factor of niobium (Nb) superconducting radio frequency cavities. High vacuum furnace baking is commonly preferred for its practicality in large-scale processing. However, surface contamination, such as niobium carbide formed during vacuum furnace baking, can limit the quench field and degrade the quality factor of the cavity. To investigate this effect, a 1.3 GHz single-cell Nb cavity underwent mid-T baking, followed by a chemical treatment to remove the surface contaminants. Post-treatment measurements revealed a significant improvement in both the quality factor and the quench field.