Numerical Siumulation of Coupler Cavities for Linacs

We present the numerical procedures involved in the evaluation of the performance of coupler cavities for linacs.The MAFIA code is used to simulate an X-Band accelerator section in the time domain.The input/output coupler cavities for the structure are of the symmetrical doubleinput design.We calculate the transmission properties of the coupler and compare the results with measurements.We compare the performance of the symmetrical doubleinput design with that of the conventional single-input type by evaluating the field amplitude and phase asymmetries.We also evaluate the peak field gradient in the coupler.