Adoption of the ASDEX Upgrade pumping to Hydrogen released by an in vessel cryo pump

Abstract Detached divertor scenarios at ASDEX Upgrade (AUG) need high gas fluxes, which are mainly pumped with the gas binding in-vessel cryopump (CP). To cope with the large quantities of hydrogen released from the CP during regeneration, a hydrogen compatible pumping system (HCPS), which is built to comply with safety regulations for explosion protection, has been built up in parallel to the already existing gas transfer pumping system (TPS). The amount of gas injected in the vacuum vessel (VV) is limited by an additional volume added to the gas inlet system. A fully automated procedure has been implemented for comprise with safety regulations. This includes daily tests of the components and communications with other relevant systems.