New design techniques on matching couplers for traveling-wave accelerating structures

Numerical optimizations on couplers of the traveling-wave (TW) accelerating structures usually require lots of calculation resources. This paper proposes a new technique for matching couplers to an accelerating structure in a more efficient and accurate way. It combines improved Kroll method with improved Kyhl method, thereby simplifying simulation process while achieving a high accuracy. This paper also presents the detailed design on couplers for a C-band constant-gradient (CG) accelerating structure based on this new technique. Such a new technique can be widely used for any TW accelerating structures working at different frequencies of S-band, C-band, and X-band including CG, constant-impedance (CI), and other structures with either electric couplers or magnetic couplers.