Active Support for Linear Collider

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The next generation linear colliders should have extremely small emittance in order to achieve sufficiently high luminosity, such as 1×10^<33> to 1×10^<34> cm10^<-2>sec10^<-1>. The very small beam size of less than ten nanometers height at the interaction point is essential, then these machines are very sensitive to the ground motion leading to uncorrelated machine component jitter. Precise alignment of the machine components is essential to prevent emittance dilution. Hardware R＆D on the C-band (5712 Mhz) RF-system for the electron/positron linear collider started in 1996 at KEK.The progresses have been reported in the international conferences. The report said the tolerance of the accelerating structure is 30 microns and the tolerance of the focusing elements is 1 micron. In our study, we have designed the girder for the accelerating structures, the active movers which support the girder. In parallel to these design, we have also studied about the ground motion for wide frequency range to obtain the realistic design concept. In order to compensate the ground motion, an active supporting mover was developed using new idea. We have undertaken to test the quality for long term use of the mover. The mover is composed of an air-spring and a Multi-Layer-Rubber-Bearing (MLRB). The air-spring gives smooth and fine control comparing with the mechanical jack. We use MLRB to prevent fast popping motion of the supporting girder induced by earthquake. Detailed designs of the control system for the mover have been done using LON controller. We have made an analysis using the finite element method on the PC concrete girder.