Developments of 700-MHz 5-cell superconducting cavities for APT

We have manufactured a total of six /spl beta/=0.64, 700-MHz 5-cell cavities. The APT (Accelerator Production of Tritium) specification requires Q/sub 0/>5/spl times/10/sup 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 maximum low-field Q0 of 3.6/spl times/10/sup 10/ at 2 K. The present limitations are available input power, field emission and quench. This type of cavities will also be used for an ADTF (Accelerator-Driven Test Facility) for AAA (Advanced Accelerator Applications) project.