Design of precision alignment of compact linear colliders accelerating structures: Master's thesis

This thesis evaluates different assembly methods for particle accelerator called Compact Linear Colliders (CLIC)accelerating components. This work focuses on the definition of a strategy and mechanical design for the assembly of four quadrants in radial and longitudinal direction. The study takes into account the constraints specified by the various aspects of the physics involved in the application of such accelerating structures. The possible deformations due to a kinematic or elastic assembly and its influence on the final accuracy are calculated. Also the work considers the effect of a moderate temperature rise due to the steady state heating during machine operation and other loads due to the function of the machine. Accelerating structures must be aligned around the beam axis with a transversal accuracy of +/-0.003 mm and longitudinal accuracy of +/-0.01 mm over the length of a single module. This requirement includes the accuracy of the parts to be manufactured and the precision of the assembly of the various components. There were three main assemblies types studied; pin assembly, sphere assembly and averaging shape assembly. A program was written to compare the different methods with respect to the mechanical differences and manufacturing tolerances. In addition, the effects of different kind of loads affecting the structures were studied via FEM-programs. These results were then used to compare and evaluate the different mechanical configurations mechanical behavior and the effects on the final results. The best assembly method can be chosen by using these comparing results. The results
indicated that with the averaging shapes it is possible to exploit the elastic behavior of the structure to achieve the final assembly accuracy. This accuracy is also acceptable for the accelerating structures.