All bare DQW crab cavities produced and qualified

By Rama Calaga and Nuria Valverde Alonso (CERN)

Following etching and most-recent tests of the final 6 bare DQW crab cavities delivered to CERN earlier this year, the whole DQW series has been qualified. 

The contract to build 10 series DQW crab cavities cavities, starting with a prototype, was awarded to Research Instruments (RI) in 2018. This was re-scoped in 2022 to 8 series cavities, with the remaining 2 cavities to be manufactured at CERN. 

RI delivered the first pair of series cavities in 2022. After successful RF testing at 2 Kelvin, and well beyond the specification, RI completed the final step of the assembly of a Helium tank (aka jacketing) on each of the two cavities in August 2023. The two jacketed cavities also qualified well beyond the specification and were equipped with HOM couplers and a field antenna in their final configuration (aka dressed cavities) before cryostating. Both dressed cavities reached above the specification and, along with the CERN-built cavities, were sent to UK-STFC for their cryostating into the first two series cryomodules for the HL-LHC.