• R. Zennaro, A. Grudiev, G. Riddone, A. Samoshkin, W. Wuensch
  CERN, Geneva
• T. Higo
  KEK, Ibaraki
• S.G. Tantawi, J.W. Wang
  SLAC, Menlo Park, California

Demonstration of a gradient of 100 MV/m at a breakdown rate of 10-7 is one of the key feasibility issues of the CLIC project. A high power rf test program both at X-band (SLAC and KEK) and 30 GHz (CERN) is under way to develop accelerating structures reaching this performance. The test program includes the comparison of structures with different rf parameters, with/without wakefield damping waveguides, and different fabrication technologies namely quadrant bars and stacked disks. The design and objectives of the various X-band and 30 GHz structures are presented and their fabrication methods and status is reviewed.