Development of SLA 3D printed volumes for leak testing of LHC Hi-Lumi cryomodules at STFC

Daresbury Laboratory recently completed the build of a Radio Frequency Dipole (RFD) crab cavity cryomodule for the Super Proton Synchrotron (SPS). During the build the team faced challenges leak testing welds which could not be tested in the typical evacuation method. Each cryomodule build requires 34 unique cryogenic and insulation vacuum weld configurations, most of which are repeated across multiple weld sites. Each weld must be qualified inspected and tested (visual and leak) before the build can progress. A suite of bespoke 3D printed weld test tools and procedures have been developed with major savings to time and cost and improved quality of leak testing tooling, developing a methodology which can be adapted to many different weld configurations. All whilst maintaining a baseline leak rate of <5e-12 mbar L/s at or below 1e-3 mbar. The result was a repeatable and cost-effective means of performing high-accuracy leak tests in a short timescale. • STFC has built its first cryomodule for the CERN LHC – High luminosity project. • SLA 3D printed plastic volumes are a cost-effective material for leak detection. • Using Accura25, volumes have been printed that reach 1E-03 – 1E-04 mbar. • Accura25 vol have been used to leak test with <5E-12 mbar l/s accuracy. • SLA parts perform equally to stainless steel during helium leak testing.