Test results of β = 0 . 64 , 700 mhz , 5-cell elliptical cavities

Six 5-cell superconducting elliptical cavities have been fabricated at LANL and in industry and tested at LANL and TJNAF. The APT (Accelerator Production of Tritium) specification requires Qo > 5 x 10 9 at an accelerating field of 5 MV/m. So far, the results of vertical tests have shown maximum accelerating fields of 12 MV/m (peak surface field of 41 MV/m and 835 Oe) and maximum Q0 of 3.6 x 10 10 at 2 K (2.1 x 10 at Eacc = 5 MV/m). The present limitations are available input power, field emission and quench. With a new 600 W amplifier and a mapping system for surface temperature and x-ray radiation, we are trying to identify and localize the emission/quench source(s) to further improve the cavity performance.