1. Chapter Editor: John Weisend TDR Chapter 6 Cryogenic System, Vacuum System & Test Stands

2. Summary Chapter describes the ESS cryogenic system, vacuum system and test stands for RF and cryomodule testing ESS cryogenic system consists of: –Linac cryoplant – provides cooling for cryomodules –Test & Instruments cryoplant – provides cooling for cryomodule test stands and Lhe for instruments –Target cryoplant – provides 16 K He cooling for the target hydrogen moderators –Distribution system – connects linac cryoplant to cryomodules

3. Summary ESS cryogenic system –Separate transfer line connects target cryoplant to moderator cooling loop –Linac cryoplant and test/instrument cryoplant share common gas management & storage system –Target cryoplant system is completely separate Due to potential tritium contamination –Sustainability (incl. efficient design, He conservation & heat recovery built into cryogenic system)

4. Summary ESS Vacuum System –Provides vacuum for linac beam line, target system and instrument lines –Vacuum levels will meet beam physics and radiation physics requirement. These levels will range widely from 10 -4 torr in some of the warm sections to better than 10 -10 torr in the cryomodule beam tubes at cryogenic temperatures –Cryomodule insulation vacuums are not expected to be continuously pumped after they have been established. But the ability to easily attach portable pumping units will exist. –The vacuum system design uses well established technology and procedures based on the experience at similar facilities: SNS, JLab, JPARC, LHC –The ESS vacuum system has low technical risk –ESS will establish common vacuum facilities & tools to support this work

5. Summary Test Stands –Provides testing & validation of both RF equipment (klystrons & modulators) and cryomodules –RF equipment testing will likely be done in a temporary location to meet project schedule –Cryomodule testing will be carried out at the ESS site Cryogenics supplied by Test & Instrumentation cryoplant Cryogenic connection to cryomodules in the test stands will prototype similar connections in the linac tunnel –All cryomodules will be tested at nominal operating temperatures and RF power in the test stands before tunnel installation –Uppsala test stand will test spoke CM prototype & spoke CM series production –Lund test stands will test all elliptical cryomodules –Lund test stands will retain capability to test spoke CMs