Conveners
Operation of SRF Facilities
- Jiquan Guo (JLAB)
Operation of SRF Facilities
- Andrei Lunin (FNAL)
Operation of SRF Facilities
- Nicoleta Baboi (MDI (Diagnose & Instrumentierung))
Some of the higher order mode (HOM) passbands in multi-cell accelerating structures may become “flat”, i.e., having a very narrow bandwidth, due to very weak coupling between cells. In the presence of misalignments, this passband disintegrates into individual cell resonances that are not coupled to the beam pipes and, therefore, have a high quality factor and R/Q. These resonances can lead to...
As part of the High Luminosity LHC (HL-LHC) upgrade, crab cavities will be installed near the ATLAS and CMS experiments to mitigate luminosity loss from large crossing angles. To accommodate the differing crossing planes, two compact cavity designs have been developed: the Double Quarter Wave (DQW) resonator and the RF Dipole (RFD) cavity. Both cavity types have been prototyped, built, and...
As part of the High Luminosity project of the Large Hadron Collider (LHC) at CERN, transverse deflecting cavities (crab cavities) have been developed to compensate for the luminosity reduction caused by the collision crossing angle. Initial estimations of the cavity HOM power in 2018 were not in agreement with measurements of the prototype cavities when tested with beam. Advancements in...
SuperKEKB is a luminosity frontier collider for electron and positron beams. One of the highly challenging targets is the RF system handling extremely large beam loading. The design beam current of the 4 GeV positron beam is 3.6 A and that of the 7 GeV electron beam is 2.6 A. The positron beam is accelerated by twenty-two normal-conducting ARES cavities, which are three-coupled cavity systems....
The conceptual design of the UK XFEL facility responds directly to user community requirements for a next-generation X-ray facility. Surveys and consultations highlighted the need for higher repetition rates, near-transform-limited pulses, broader photon energy coverage, and the capacity to serve many experiments simultaneously. Current facilities typically offer only 1–3 source points,...
The study investigated the continuous-wave (CW) performance of the spare 3.9 GHz third harmonic cryomodule for the European XFEL. While pulse mode operation exceeded specifications with high accelerating gradients, CW tests revealed strong limitations. The main issue was overheating of the first HOM coupler. Additional challenges included tuner backlash and mechanical resonances at 18.6 Hz...
