The coupled dipole modes of the NLC accelerator structure

The proposed accelerator cavity of the Next Linear Collider is discussed. The Gaussian detuning method for solving the problems arising from transverse wakefields is studied when coupling is included. The detuned cavity is modelled by a chain of coupled resonant circuits, with each loop of the chain representing one cavity cell. By solving a matrix eigenvalue problem the frequencies and kick factors of the normal modes of the cavity are obtained which, in turn, give the wakefield. The process is repeated using a double band of circuits to model the cavity, which duplicates the dispersion curves of the lowest two bands more accurately. (K.A.) 15 refs.; 8 figs