Performance of a CEBAF Production Cavity after High-Temperature Heat Treatment*

CEBAF’s production cavities are tested in a vertical configuration after appropriate chemical surface treatment prior to installation into the accelerator. The performance of these cavities is excellent often exceeding the specifications of Eaa=S MV/m at 2 K by factors of 2 to 3. In such cases the cavities are often limited by thermal-magnetic breakdown. A cavity that exhibited a limiting gradient of Eaccsl6.4 MVlm has been heat-treated at 14OOoC for 6 hours in the presence of titanium as a solid state gettering material to improve the thermal stabilty of the niobium. After the heat treatment a gradient of Eacc--20.5 MV/m corresponding to a peak surface electric field of Epe&--52 MV/m has been measured. In addition to the cavity results, data on thermal conductivity and tensile properties of samples which have undergone the sam