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@inproceedings{lumpkin:ipac2021-tupab274, author = {A.H. Lumpkin and J.A. Diaz Cruz and D.R. Edstrom and B.T. Jacobson and P.S. Prieto and J. Ruan and J.P. Sikora and R.M. Thurman-Keup and F. Zhou}, % author = {A.H. Lumpkin and J.A. Diaz Cruz and D.R. Edstrom and B.T. Jacobson and P.S. Prieto and J. Ruan and others}, % author = {A.H. Lumpkin and others}, title = {{Investigations of Long-Range Wakefield Effects in a TESLA-type Cryomodule at FAST}}, booktitle = {Proc. IPAC'21}, pages = {2109--2112}, eid = {TUPAB274}, language = {english}, keywords = {HOM, cavity, electron, cryomodule, wakefield}, venue = {Campinas, SP, Brazil}, series = {International Particle Accelerator Conference}, number = {12}, publisher = {JACoW Publishing, Geneva, Switzerland}, month = {08}, year = {2021}, issn = {2673-5490}, isbn = {978-3-95450-214-1}, doi = {10.18429/JACoW-IPAC2021-TUPAB274}, url = {https://jacow.org/ipac2021/papers/tupab274.pdf}, note = {https://doi.org/10.18429/JACoW-IPAC2021-TUPAB274}, abstract = {{The preservation of low emittance of electron beams during transport in the accelerating structures of large facilities is an ongoing challenge. In the cases of the TESLA-type superconducting rf cavities currently used in the European X-ray Free-electron Laser (XFEL) and the under-construction Linac Coherent Light Source upgrade (LCLS-II), off-axis beam transport may result in emittance dilution due to transverse long-range wakefields (LRWs) and short-range wakefields (SRW)***. To investigate such effects, experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility with its unique configuration of two TESLA-type cavities after the photocathode rf gun followed by an 8-cavity cryomodule CM). We generated beam trajectory changes with the H/V125 corrector set located 4 m upstream of the cryomodule. At 125 pC/bunch, 50 bunches, 25-MeV input, and 100-MeV exit energy, we observed for the first time submacropulse position slews of up to 500 microns at locations ~3 m after the CM and a centroid oscillation at a difference frequency of 240 kHz further downstream. Both are emittance-dilution effects which we mitigated with selective upstream beam steering.}}, }