| AVS 63rd International Symposium & Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT-TuA |
| Session: | Accelerator and Large Vacuum Systems |
| Presenter: | Peter Ladd, European Spallation Source, Sweden |
| Correspondent: | Click to Email |
The European Spallation Source (ESS) is a multi-disciplinary research center based on the world’s most powerful neutron source being built in Lund, Sweden . The facility design and construction includes the most powerful linear proton accelerator ever built, helium-cooled tungsten target wheel, state-of-the-art neutron instruments, a suite of laboratories, and a supercomputing data management and software development center . The LINAC will deliver 5 MW of power to the target at 2000 MeV. Ground breaking took place in September 2014 and construction is rapidly progressing towards first neutron on target scheduled for mid 2019 .
ESS is a long pulse superconducting linac that accelerates protons in 2.86 ms long pulse stream with a repetition rate of 14 Hz at a 4 % duty cycle providing an average beam power of 5 MW. The stream of protons is intercepted by a helium cooled tungsten target wheel where about 10% are converted to mass, through the nuclear reactions in the spallation process and the remaining 90% is deposited as heat within a distance of about 1m from the target wheel. The moderators and reflectors maximize the yield directing the flow of neutrons to a suite of neutron instruments through neutron guides.
The “Target `Monolith Vessel” (CPMV) is a vacuum vessel nominally 6m in diameter x 9m high fabricated of 304 stainless steel. The major equipment located within this vessel are the helium cooled target wheel, 42 actively cooled neutron beam port inserts that connect to the external neutron guides, actively cooled moderators and reflector plugs and water cooled radiation shielding blocks. The CPMV is designed to operate either under a helium atmosphere, normally at 1 bar pressure, or under high vacuum and is directly connected to the accelerator beam-line that operates under ultra high vacuum conditions. A proton beam window (PBW) physically separates the two environments when the monolith is under a helium atmosphere and in the vacuum mode the PBW is removed and the two vacuum environments are directly connected.
The paper presented reviews the various aspects of the Vacuum Design of the Target Monolith System including material selection, surface finishes and construction issues, equipment sizing and selection and the development of a Strategic Installation and Test Strategy in order to minimize project risk.