Three-dimensional finite element heat transfer and thermal stress analysis of rf structures

Thermal expansion and thermal stress induced strain cause the detuning and limit the power level of radiofrequency (rf) structures. Two-dimensional finite element modeling has been used to determine the operating power limits of coupled cavity systems [1] , but for complex high power accelerator structures without axial symmetry, a three-dimensional analysis is necessary. This paper describes results of a three-dimensional finite element temperature and thermal stress analysis. The analysis was performed for a high power coupled cavity linac structure operating at 1350 MHz. The results of the analysis are used to determine changes in the structure rf parameters as a function of power level and cooling water velocity.