Speaker
Description
Air Liquide Advanced Technologies is pleased to share the results and lessons learnt through the start-up of SLAC 2K cryogenic module. 2K temperature is reached by pumping down the accelerator cavities filled with liquid helium to subatmospheric pressure. In order to pump the cavities down to 30 mbara, a train of 5 high speed cold compressors on magnetic bearings is used. Magnetic bearings allow for resilient operation of the cold compressors with changing operating conditions in terms of pressure, temperature and rotating speed.
The tuning of the cold compressor speeds throughout the pump-down is key to reach stable operation at 2K, so as to maintain all 5 compressors within their nominal operating range. In particular, stabilizing the pressure at the end of the pump-down, while liquid helium in the cavities enters superfluid state and gaseous density becomes very low, can prove challenging. Air Liquide Advanced Technologies will present the final “pump-down path” established for SLAC, and how the tuning was performed, allowing for a reproducible, reliable and fast pump-down on SLAC cryogenic installation. Test results showing the assessment of the minimum and maximum operating flow at 2K will also be presented.
