Development of under-cut type RF window for 50 kW power coupler

A Coaxial loop type coupler has been developed for testing of accelerator cavities for LEHIPA Project (Low Energy High Intensity Proton Accelerator) at BARC. This RF coupler is designed to handle up to 50 kW RF power at different frequencies (350 MHz and 352.2 MHz with maximum 1% duty cycle). A disc type alumina window with under-cuts on inner conductor is integrated in the coupler assembly for impedance matching. This design is simpler than choke type or undercut — overcut type impedance matching schemes for coaxial RF windows. Full wave EM analysis of RF window is presented here. The window fabrication, testing, RF characterization and high power conditioning results are also discussed.