| Paper | Title | Page |
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| TPPT082 | High Thermal Conductivity Cryogenic RF Feedthroughs for Higher Order Mode Couplers | 4108 |
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Funding: This manuscript has been authorized by SURA, Inc. under Contract No. DE-AC05-84ER-40150 with the U.S. Department of Energy. The use of higher-order-mode (HOM) pickup probes in the presence of significant fundamental rf fields can present a thermal challenge for cw or high average power SRF cavity applications. The electric field probes on the HOM-damping couplers on the JLab "High Gradient" and "Low Loss" seven-cell cavities for the CEBAF upgrade are exposed to approximately 10% of the peak magnetic field in the cavity. To avoid significant dissipative losses, these probes must remain superconducting during operation. Typical cryogenic rf feedthroughs provide a poor thermal conduction path for the probes, and provide inadequate stabilization. We have developed solutions that meet the requirements, providing a direct thermal path from the niobium probe, thorough single-crystal sapphire, to bulk copper which can be thermally stationed (or heat sunk). Designs, electromagnetic and thermal analyses, and performance data will be presented. |