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TY - CONF AU - Baudrenghien, P. AU - Mastoridis, T. ED - Schaa, Volker RW TI - LLRF Studies for HL-LHC Crab Cavities J2 - Proc. of HB2018, Daejeon, Korea, 17-22 June 2018 C1 - Daejeon, Korea T2 - ICFA Advanced Beam Dynamics Workshop T3 - 61 LA - english AB - The HL-LHC upgrade includes sixteen Crab Cavities (CC) to be installed on both sides of the high luminosity experiments, ATLAS and CMS. Two issues have been highlighted for the Low Level RF: transverse emittance growth (and associated luminosity drop) caused by CC RF noise, and large collimator losses following a CC trip. A prototype cryomodule with two CCs has been installed in the SPS, and tests have started in May 2018 with beam. This paper briefly reports on preliminary results from the SPS tests. It then presents emittance growth calculations from cavity field phase and amplitude noise, deduces the maximum RF noise compatible with the specifications and presents a possible cure consisting of a feedback on CC phase and amplitude. To reduce the losses following a CC trip we propose to implement transverse tail cleaning via the injection of CC noise with an optimized spectrum, which selectively excites the particles of large transverse oscillation amplitudes. PB - JACoW Publishing CP - Geneva, Switzerland SP - 440 EP - 445 KW - cavity KW - feedback KW - emittance KW - luminosity KW - betatron DA - 2018/07 PY - 2018 SN - 978-3-95450-202-8 DO - 10.18429/JACoW-HB2018-THP2WC02 UR - http://jacow.org/hb2018/papers/thp2wc02.pdf ER -