| Paper | Title | Page |
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| WEPEC079 | Design and Prototype Progress toward a Superconducting Crab Cavity Cryomodule for the APS | 3061 |
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A squashed, elliptical supercondconducting (SC) cavity with waveguide dampers on the beam pipes has currently been chosen as the baseline design [1] for the Short Pulse X-ray (SPX) project at the Advanced Photon Source (APS). An alternate cavity design, with a waveguide damper located directly on the cavity cell for improved damping characteristics, has also been designed and cold-tested with promising results. In either case, eight cavities would be operated CW in a single cryomodule at 2K to produce an electron bunch chirp of 4MV at a frequency of 2.815 GHz. Detailed analysis of multipactoring (MP), lorentz force detuning (LFD), and the thermal properties of the baseline design has led to an engineering specification of the basic parameters of the cryomodule. |
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| THPEB059 | Adjustable High Power Coax RF Coupler with No Moving Parts | 4008 |
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An extremely low emittance RF gun is being designed for the X-ray Free Electron Laser Oscillator (XFEL-O), which is now being proposed by ANL. An adjustable coupling factor for this gun is very desirable for providing operational flexibility. What is required is a fundamental RF power coupler (FPC), adjustable in situ, that can operate at 100 MHz and 200 kW CW. If rotational motion is used in the adjustable coupler, it is usually necessary to break the vacuum between the coupler and the RF cavity, thereby risking prolonged down-times and the introduction of contaminants into the vacuum system. We propose a novel system for adjusting the coupling coefficient of coaxial couplers to allow for individual control and adjustments to the RF fields under different beam loading scenarios. The RF coupler has no movable parts and relies on a ferrite tuner assembly, coax TEE, and double windows to provide a VSWR of better than 1.05:1 and a bandwidth of at least 8 MHz at 1.15:1. The ferrite tuner assembly on the stub end of the coax TEE uses an applied DC magnetic field to change the Qext and the RF coupling coefficient, β, between the RF input and the cavity. |