Abstract:
In the construction of Hefei advanced light facility (HALF), vacuum components of superconducting materials are widely used, especially superconducting radio frequency cavity. The superconducting cavity with the characteristics of high accelerating gradient, low beam impedance, high unloaded quality factor and low operating cost has become the first choice for large accelerators in the 21st century. However, electron cloud (EC) phenomenon is generated by the secondary electron emission on the surface of the superconducting cavity and cryogenic vacuum chamber. Deposition of extra dose secondary electron multiplicative power can induce thermal load increase in the cryogenic zone, superconducting cavity quench and so on. Therefore, reduction of the secondary electron emission in the superconducting radio frequency cavity is a great challenge for the design of HALF. On the basis of secondary electron yield (SEY) measurement system for room temperature materials, the authors independently designed the cryogenic sample rack to allow liquid helium to flow through the sample stage and cool sample by heat conduction. It was significant to calculate heat leakage for deciding refrigerating capacity and liquid helium consumption rate. After the system integration and debugging, the cooling performance test was carried out. The results show that cryogenic SEY measurement system was established.