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@inproceedings{camacho:ipac2022-mopotk045, author = {O. Camacho and A. Halavanau and R. Robles}, title = {{Generation of High Emittance Ratios in High Charge Electron Beams at FACET-II}}, booktitle = {Proc. IPAC'22}, % booktitle = {Proc. 13th International Particle Accelerator Conference (IPAC'22)}, pages = {560--563}, eid = {MOPOTK045}, language = {english}, keywords = {emittance, quadrupole, experiment, laser, cathode}, venue = {Bangkok, Thailand}, series = {International Particle Accelerator Conference}, number = {13}, publisher = {JACoW Publishing, Geneva, Switzerland}, month = {07}, year = {2022}, issn = {2673-5490}, isbn = {978-3-95450-227-1}, doi = {10.18429/JACoW-IPAC2022-MOPOTK045}, url = {https://jacow.org/ipac2022/papers/mopotk045.pdf}, abstract = {{Experiments foreseen at FACET-II, including dielectric plasma wakefield acceleration and linear collider tests, call for electron beams with highly asymmetric transverse emittances - so called "flat beams". A canonical recipe for the generation of such beams is injecting a magnetized beam at a waist into an appropriately tuned skewed quadrupole triplet channel. However, due to the intense non-linear space-charge forces that dominate nC bunches, this method presents difficulties in maintaining the flatness. We proceed with generalized round-to-flat-beam (RTFB) transformation, which takes into account the non-negligible divergence of the beam at the channel entrance, using a quartet of skewed quadrupoles. Our analytical results are further optimized in ELEGANT and GPT simulation programs and applied to the case of the FACET-II beamline. Non-ideal cathode spot distributions obtained from recent FACET-II experiments are used for accurate numerical modeling. Tolerances to quadrupole strengths and alignment errors are also considered, with an eye towards developing hardware specifications.}}, }