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TY - CONF AU - Repond, J. AU - Damerau, H. AU - Lasheen, A. AU - Shaposhnikova, E.N. ED - Koscielniak, Shane ED - Satogata, Todd ED - Schaa, Volker RW ED - Thomson, Jana TI - Lower-Harmonic RF System in the CERN SPS J2 - Proc. of IPAC2018, Vancouver, BC, Canada, April 29-May 4, 2018 C1 - Vancouver, BC, Canada T2 - International Particle Accelerator Conference T3 - 9 LA - english AB - Significant beam losses increasing with intensity are observed at capture and along the SPS flat bottom for the LHC-type proton beam. The intensity should be doubled for HL-LHC and high losses may be a major performance limitation. Bunches extracted from the PS, the SPS injector, are produced in a 40 MHz RF system applying a bunch rotation at the end of the cycle and therefore cannot be perfectly matched to the 200 MHz SPS RF bucket. The possibility of using a lower harmonic additional RF capture system in the SPS was already proposed after the LEP era in preparation for transfer of the LHC beam but the bunch rotation was the preferred solution, since the induced voltage in the SPS 200 MHz RF system would be too large to ensure stability in a low harmonic system without mitigation measures. However, the use of the upgraded one-turn feedback and the 200 MHz RF system as a Landau cavity could help to improve stability. The feasibility of this scenario to reduce capture losses in the SPS is analysed and presented in this paper. The choice of an optimum RF frequency and voltage is also discussed. The transfer to the main 200 MHz is simulated using a realistic bunch distribution. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3087 EP - 3090 KW - emittance KW - impedance KW - simulation KW - cavity KW - proton DA - 2018/06 PY - 2018 SN - 978-3-95450-184-7 DO - 10.18429/JACoW-IPAC2018-THPAF053 UR - http://jacow.org/ipac2018/papers/thpaf053.pdf ER -