| 摘要 |
An on-axis rf power coupler for a superconducting particle accelerator includes a coaxial coupler tube that passes through a rf waveguide stub connected to a rf power source. The coupler tube is movable in translation along the axis of the beam path by a piezoelectric drive to permit variation of the coupling between the rf power source and the resonant signal in the accelerator. A tubular rf window extending through the waveguide stub, together with a vacuum bellows assembly connected to the coupler tube, isolate the vacuum inside the accelerator cavity from the vacuum in the rf waveguide and stub. A choke joint in the wall of the waveguide selectively passes unwanted HOM signals out of the waveguide stub and away from the accelerator cavity, where they are dissipated by ferrite tiles on the coupler tube. The upstream end of the coupler tube and a tubular extension of the accelerator cavity form a coaxial line for introducing rf power into the accelerator. Further, the upstream end of the coupler tube separates the rf signal in the cavity from unwanted HOM signals and diverts the latter through the choke joint for isolation and dissipation. |
