Improvements of Test System for Couplers

The 162.5 MHz HWR010 and HWR015 superconducting cavities have been used in the Chinese ADS 25 MeV demo SRF Linac. Each cavity is feed with RF power by one high power coupler. The maximum design coupler power is 20 kW in traveling mode. Prior to assembly, couplers need to be tested and conditioned at room temperature. And the characteristics of conditioning phenomenon can also be thoroughly studied during the conditioning process. Figure 1 presents the block diagram of the test stand system. However, the previous test system is ineligible because of its sundry problems lying in its LLRF control system and its test stand. To overcome the defects of the previous test system, a series of improvements were performed.