Speaker: Ivan Karpov (BE-RF-BR)
Beam loading and RF power evaluation for high-current colliders
The interaction of the beam with the fundamental impedance of the accelerating RF cavities can limit the performance of high-current accelerators. Transient beam loading can result in a significant variation of bunch-by-bunch parameters (bunch length, synchronous phase, etc.), which needs to be carefully evaluated to avoid possible luminosity reduction in colliders. In this seminar, we discuss beam-loading limitations, which drive the design of the RF systems of the Future Circular electron-positron and hadron-hadron Colliders (FCC-ee,-hh).
Evaluation of beam-induced transients is challenging for these machines due to a large number of circulating bunches (more than 10000 per beam). That is why the accurate analytic approach needs to be developed and applied instead of macro-particle tracking simulations. As the result, modulations of bunch-by-bunch parameters can be calculated and, if needed, they can be reduced by means of the direct RF feedback. This measure, however, results in increased RF power consumption depending on the compensation scheme. The developed model was extended to describe the power transients during filling of the Large Hadron Collider (LHC). This study was motivated by potential power limitations for High-Luminosity LHC beam intensities.