Efficient approach for optimizing couplers in traveling-wave accelerating and deflecting structures

A new design technique combining the improved Kyhl method with the improved Kroll method has been developed to efficiently match couplers for traveling-wave (TW) accelerating structures [Z. Huang , ]. However, such a new technique requires some complicated modifications for the TW deflecting structure operating at HEM mode. This paper proposes a more efficient and universal approach for designing couplers in any TW structures including accelerating and deflecting structures. This approach is based on a new criterion <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mrow><a:mo stretchy="false">|</a:mo><a:mrow><a:msub><a:mrow><a:mi>R</a:mi></a:mrow><a:mrow><a:mi>c</a:mi></a:mrow></a:msub></a:mrow><a:mo stretchy="false">|</a:mo></a:mrow><a:mo>→</a:mo><a:mn>0</a:mn></a:mrow></a:math> and an equivalent circuit model to facilitate fast and accurate optimizations. By using this new approach, the optimizations on couplers for any TW structures with arbitrary starting dimensions can converge in just several iterations, significantly simplifying the overall design process while maintaining a high accuracy.