JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
TY - CONF AU - Intelisano, L. AU - Damerau, H. AU - Karpov, I. ED - Gianfelice, Eliana ED - Nagaitsev, Sergei ED - Kim, Dong Eon ED - Marx, Michaela ED - Schaa, Volker R. W. TI - Threshold for Loss of Longitudinal Landau Damping in Double Harmonic RF Systems J2 - Proc. of HB2021, Batavia, IL, USA, 04-08 October 2021 CY - Batavia, IL, USA T2 - ICFA ABDW on High-Intensity and High-Brightness Hadron Beams T3 - 64 LA - english AB - Landau damping is a natural stabilization mechanism to mitigate coherent beam instabilities in the longitudinal phase space plane. In a single RF system, binominal particle distributions with a constant inductive impedance above transition (or capacitive below) would lead to a vanishing threshold for the loss of Landau damping, which can be avoided by introducing an upper cut-off frequency to the impedance. This work aims at expanding the recent loss of Landau damping studies to the common case of double harmonic RF systems. Special attention has been paid to the configuration in the SPS with a higher harmonic RF system at four times the fundamental RF frequency, and with both RF systems in counter-phase (bunch shortening mode). Refined analytical estimates for the synchrotron frequency distribution allowed to extend the analytical expression for the loss of Landau damping threshold. The results are compared with semi-analytical calculations using the MELODY code, as well as with macroparticle simulations in BLonD. PB - JACoW Publishing CP - Geneva, Switzerland SP - 95 EP - 99 KW - impedance KW - damping KW - synchrotron KW - simulation KW - dipole DA - 2022/04 PY - 2022 SN - 2673-5571 SN - 978-3-95450-225-7 DO - doi:10.18429/JACoW-HB2021-MOP15 UR - https://jacow.org/hb2021/papers/mop15.pdf ER -