SRF cavity testing status and operating experience

The cryogenic system at the Meson Detector Building (MDB) has now supported over four years of testing of fully assembled SRF cavities. The Horizontal Test Stand (HTS) has tested single, fully dressed 1.3 GHz and 3.9 GHz cavities at 2 K as final qualification prior to their installation into accelerator-ready cryomodules. The MDB cryogenic system has been expanded to support an additional cavity test area, the Spoke Resonator Test (SRT) area, for 325 MHz single-spoke resonators. The SRT area currently supports 4.5 K operations for research and development of the spoke cavities with tuner and coupler. The test area addition required the design and installation of a new cryogenic transfer line extension to reach this second test area and to allow for independent operations of either cavity test system. The cryogenic performance and operational experiences of both cavity test areas, operating individually or simultaneously, will be discussed. The general reliability of operating the closed, subatmospheric helium system free of contaminants will be discussed. Future plans for the MDB test area include lowering the SRT temperature to 2 K and adding an additional Horizontal Test Stand (HTS-2).