Coupled RF-Thermo-Structural Analysis of CLIC Traveling Wave Accelerating Structures

Temperature changes in the CLIC accelerating structure lead to unwanted deformation. One of the aims of the CLIC module team is to optimize the necessary cooling system. The extended thermal program of the module was complemented by these thermal studies on real RF structures tested in X-band high-power test stands at CERN, Geneva (CH). The impact of thermal expansion on the RF characteristics of CLIC traveling wave accelerating structures is studied. The simulation setup in COMSOL is described in much detail. The necessary geometry simplifications are pointed out, mesh configurations are discussed by means of convergence studies, as well as important post-processing quantities are introduced which are common for characterizing traveling wave structures. The present report treats two different prototypes of the TD26_R05 design, a damped traveling wave accelerating structure using 26 cells and two matching cells, with a bending radius of 0.5 mm being applied. One of these prototypes is currently being conditioned in the Xbox2 test stand.