Superfluid Helium Cryoplant “SHP20”: Development and Initial Experiments

The SHP20, a 2 K superfluid helium cryoplant, was developed to test various cryogenic components of superconducting radiofrequency (SCRF)-based linear accelerators. Critical components of the 2 K coldbox include a 4.5 K saturated liquid helium (LHe) bath, a 2 K saturated LHe bath, a plate-fin type Joule-Thomson (JT) heat exchanger (HEX), bellow-sealed cryogenic control valves, and a liquid nitrogen (LN2)-cooled thermal shield. The developed SHP20 is integrated with the indigenous helium liquefier “LHP50”, and its cryogenic performance was tested during round-the-clock operation. Sub-atmospheric helium is compressed using a vacuum pump. The multiple switching operations between the 4.5 K standby mode and the 2 K mode were tested. The measured static heat load to the 2 K LHe bath is approximately 0.5 W. The current article briefly describes the development of the SHP20 coldbox and its components, and presents the initial test results.