Modal Analysis and Measurement of Water Cooling Induced Vibrations on a CLIC Main Beam Quadrupole Prototype

To reach the Compact Linear Collider (CLIC) design luminosity, the mechanical jitter of the CLIC main beam quadrupoles should be smaller than 1.5 nm integrated root mean square (r.m.s.) displacement above 1 Hz. A stiff stabilization and nano-positioning system is being developed but the design and effectiveness of such a system will greatly depend on the stiffness of the quadrupole magnet which should be as high as possible. Modal vibration measurements were therefore performed on a first assembled prototype magnet to evaluate the different mechanical modes and their frequencies. The results were then compared with a Finite Element (FE) model. The vibrations induced by water-cooling without stabilization were measured with different flow rates. This paper describes and analyzes the measurement results.