Fabrication Process of Rounded Damped Detuned Structure

Following the successful design and fabrication of Damped Detuned Structures (DDS), the JLC/NLC linear collider project advanced to Rounded Damped Detuned Structures (RDDS) with curved cross section of the cavity shape for increased shunt impedance. Various advanced techniques for fabricating RDDS1 disks comparing to those for DDS were established to satisfy the dimension accuracy of ± 1 µ m over the entire surface made by ultra-precision turning. These disks were assembled with almost the same stacking and bonding jigs and processes as those of DDS3 assembly. In consequence, the assembly showed little disk-to-disk misalignment within 1 µ m before and after the process. Though, it had 200 µ m smooth bowing, which was subsequently corrected as DDS3, and flares at both ends.