Commissioning of the hydrogen cryostat of the cryogenic moderator system of the European Spallation Source (ESS) for test purposes at the ZEA-1

A helium-cooled hydrogen cryostat for the European Spallation Source (ESS) was developed, built and tested at the ZEA-1 of the Forschungszentrum Jülich. In order to be able to carry out the final factory acceptance test (FAT), a nitrogen mixing system was developed with which the cryostat could be cooled down and operated in a controlled manner. During the test phase, the cryostat was operated exclusively with nitrogen instead of helium and hydrogen. Nevertheless, all functions of the cryostat system could be checked and key figures could be determined.