Experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility to elucidate the effects of long-range wakefields (LRWs) in TESLA-type superconducting rf cavities. In particular, we investigated the higher-order modes (HOMs) generated in the eight cavities of a cryomodule (CM) due to off-axis steering with correctors located ~4 m upstream of the CM. We have observed correlated submacropulse centroid slews of a few-hundred microns and centroid oscillations at ~240 kHz in the rf BPM data after the CM. The entrance energy into the CM was 25 MeV, and the exit energy was 100 MeV with 125 pC/b and 400 pC/b in 50-bunch pulse trains. These experimental results were evaluated for machine learning training aspects which will be used to inform the commissioning plan for the Linac Coherent Light Source-II injector CM.
@article{arxiv.2112.00839,
title = {Submacropulse electron-beam dynamics correlated with higher-order modes in a Tesla-type cryomodule},
author = {A. H. Lumpkin and R. Thurman-Keup and D. Edstrom and P. Prieto and J. Ruan and B. Jacobson and J. Sikora and J. Diaz-Cruz and A. Edelen and F. Zhou},
journal= {arXiv preprint arXiv:2112.00839},
year = {2022}
}