CERN, Geneva, Switzerland
A full-scale model of the double-quarter-wave (DQW) cavity towards the High-Luminosity Large Hadron Collider (HL-LHC) upgrade was built in aluminum to characterize the deflecting mode. Field strength measurements have been carried out for both the transverse and longitudinal electromagnetic fields, by using the bead-pull technique. Perturbation objects of different shapes and material were used to separate the electric and magnetic field components. A reasonably good agreement was found between numerical simulation and measurements, which confirm the reliability and accuracy of the measurements done.
DCI-UG, León, Mexico
Cockcroft Institute, Warrington, Cheshire, United Kingdom
CERN, Geneva, Switzerland
ODU, Norfolk, Virginia, USA
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
BNL, Upton, Long Island, New York, USA
Three proof-of-principle compact crab cavity designs have been fabricated in bulk niobium and cold tested at their home labs, as a first validation step towards the High Luminosity LHC project. As a cross check, all three bare cavities have been retested at CERN, in order to cross check their performance, and cross-calibrate the CERN SRF cold test facilities. While achievable transverse deflecting voltage is the key performance indicator, secondary performance aspects derived from multiple cavity monitoring systems are also discussed. Temperature mapping profiles, quench detection, material properties, and trapped magnetic flux effects have been assessed, and the influence on performance discussed. The significant effort invested in developing expertise in preparation and testing of these crab cavities has already been fruitful for all partners, and more is to come within this ongoing program.