HB2025 - the 71st ICFA Advanced Beam Dynamics workshop on High-Intensity and High-Brightness Hadron Beams

Beam Loading in the Superconducting Cavities at the European Spallation Source Linac

TUIDC05

Oct 21, 2025, 6:00 PM

30m

Room C (Conference Center)

Invited Oral Presentation WGD:Operations and Commissioning TUIDC WGD invited oral

Speaker

Emanuele Laface (European Spallation Source)

Description

During the commissioning of the ESS LINAC in early summer 2025, we recorded beam-loading transients from a 5 µs, 5 mA beam in 47 superconducting cavities: 26 Spoke and 21 Elliptical Medium Beta. We compare the beam-induced cavity voltage and current phasors with a standard beam-loaded cavity model that includes coupling, loaded $Q$, and detuning, thereby validating model parameters across the installed sections. Leveraging this agreement, we invert the measured response to compute the beam’s synchronous phase on a cavity-by-cavity basis without external timing references. The inferred phase is then used to set the optimal accelerating phase and to quantify residual phase errors and detuning during routine operation. We report sensitivity to measurement noise, pulse-to-pulse reproducibility, and the robustness of the method over the commissioning dataset, and we outline a practical procedure to commission and periodically retune SRF sections at ESS using beam-loading observables alone.