Fig. 1. 1.3 GHz 9-cell superconducting cavity and HOM coupler

Fig. 2. 1.3 GHz 9-cell HOM coupler and its equivalent circuit

Fig. 3. 1.3 GHz cavity and HOM coupler in CST

Fig. 4. The S-parameter of the HOM coupler in CST

Fig. 5. Q_e with the gap in cavity

Fig. 6. Tuning fixture of HOM couplers

Fig. 7. Magnetic field in HOM coupler

Fig. 8. Sketch showing the cross-section of the feed through parts and a photo of a DESY feedthrough

Fig. 9. Cryogenic system of 1.3 GHz module and abnormal temperature rise

Fig. 10. Thermal anchor of 1.3 GHz model HOM coupler

Fig. 11. Heat transfer flow diagram

Fig. 12. Anchor and cavity structure (the right cylinder represents the anchor)

Fig. 13. Model of HOM coupler

Fig. 14. Antenna temperature distribution when anchor is connected well

Fig. 15. Antenna temperature distribution when anchor is not connected well