Superconducting radio frequency (SRF) cavities used in modern particle accelerators require operation at 2 K with sub-atmospheric (saturation) pressure. For large-scale systems, the most practical approach is to use multi-stage cryogenic centrifugal compressors (cold compressors or CCs) to compress the sub-atmospheric helium returning from the load to positive pressure. This compressor train...
Multi-stage cryogenic centrifugal compressor (cold compressors or CCs) trains used in 2 K sub-atmospheric refrigeration systems require a transient process operation (or ‘pump-down’) to establish the target low-pressure steady-state conditions. In sub-atmospheric refrigeration systems for superconducting radio frequency (SRF) cavities, the pump-down process establishes a pressure ratio of...
The STEP program is an ambitious initiative designed to demonstrate, for the first time, a fusion energy prototype power plant capable of delivering net power (>~100 MWe) to the electrical grid. Planned for construction in West Burton, Nottinghamshire, UK, the tokamak system will utilise high-temperature superconducting (HTS) coils to generate and sustain the magnetic field needed to confine...
The End Station Refrigerator 2 (ESR2) is the eventual replacement for the ESR1. ESR2 is a refurbished cryoplant comprised of the cold box and compressors of the 4 kW at 4.5K ASST-A plant from the Superconducting Super Collider in Texas. Additionally, ESR2 is equipped with a 10 m3 liquid helium Dewar, cryogenic distribution system including more than 50m long cold transfer line, control...
The SLAC National Accelerator Laboratory is home to LCLS-II, a world-class X-ray laser. The LCLS-II superconducting linac is supported by a cryogenic system comprising two identical subsystems, each featuring a warm helium compressor system, an 18 kW (at 4.5 K) coldbox, and a 5-stage 2 K cold compressor train with a cooling capacity of 4 kW at 2.0 K. Installed and commissioned between 2018 and...
