A tunable waveguide to cavity coupler for high power accelerator cavities

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• 作者：Rajesh Kumar^a ; ^{krajesh@barc.gov.in} ; ^{rkthakur_iitk@yahoo.com} ; P. Singh^a ; Divya Unnikrishnan^b ; Girish Kumar^b
• 关键词：Waveguide iris coupler ; Ridge waveguide coupler ; Coupling coefficient ; Waveguide to cavity coupling ; External quality factor ; Tunable coupler
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2012
• 出版时间：1 February 2012
• 年：2012
• 卷：664
• 期：1
• 页码：203-213
• 全文大小：1132 K

文摘

The end iris ridge waveguide couplers are used to couple power to accelerator cavities through a reduced size coupling port. However, higher electric and magnetic fields due to reduced size lead to strict requirements on dimensional tolerances during coupler fabrication process. It is shown by detailed parametric analysis that even small dimensional changes during manufacturing or operation can lead to undesired shift in design frequency and deterioration of return loss. Hence, transmitted power testing of two couplers connected back to back without an intermediate cavity cannot be carried out. Here, we propose cylindrical static tuners on impedance matching section to relax the dimensional tolerance requirements. It is also shown that an iris coupled coupler-cavity system is more tolerant towards coupler dimensional changes than a stand-alone coupler. However, same tuners can find use for tuning the coupling coefficient of coupler-cavity system. The proposed tuning scheme is expected to reduce the coupler manufacturing costs and provide an useful alternative for coupling coefficient tuning over iris machining.