Performance of normal conducting structures for linear colliders

We describe the status of the design, fabrication and various performance studies such as high-field characteristics and wakefields on the accelerating structures for the linear collider linacs for CLIC, VLEPP, NLC, JLC and SBLC. The structure design and fabrication for single-bunch machines has almost finished, while those for the multi-bunch operation are in progress. For the design of the latter structures, various calculation methods of the long-range wakefield are discussed in addition to the experimental evaluation of the HOM parameters. A direct measurement of the long-range wakefield in a detuned structure was successfully performed and was proved to be a nice tool for the evaluation of design and fabrication of the structure. In addition, the beam induced dipole modes coming out of the coupler into the waveguide was measured which makes it possible to use the accelerating structure as the BPM. A heavily damped choke-mode structure for the S-band was tested at high power showing stable operation at more than 50 MV/m. Another choke-mode structure with integrated damping loads is in progress. Stable operation of the disk-loaded structures from the S-band to 30 GHz were verified. Fabrication studies are proceeding in all projects focusing on various issues such as a good alignment, cheapness and low dark current.