Coupling factor can be increased as well as decreased => cavity design for desired coupling => safety margins included in coupler design TaCo machined in one process (T-type: short circuit machined after RF measurements -> delay) RF matching simple and quick (final RF contact between coupler and cavity) Change of beam current => exchange of plunger tuner Movable tuner => variable coupling during operation TaCo applications: Linac4 / SPL 26 TaCos (20 x decrease β, 5 x increase β, 1 x variable β) 09/12/11 TaCo // Tuner-adjustable waveguide Coupler 14
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