Speaker
Description
In recent years, adiabatic trapping into non-linear resonances has been used to split a charged beam into multiple beamlets for multi-turn extraction. This beam manipulation is the standard operational mode at the CERN Proton Synchrotron (PS) to deliver proton beams for the fixed-target programme at the Super Proton Synchrotron (SPS). These manipulations are sensitive to space-charge effects, as demonstrated by dedicated experiments and numerical simulations. As the transverse beam distribution changes significantly during the process, this phenomenon cannot be modelled using standard approximations.
We developed a GPU-accelerated, performance-portable code to simulate
the evolution of the transverse beam distribution during the splitting process, enabling the CPU-intensive simulations required to study adiabatic effects. We used a Particle-In-Cell scheme to compute the charge density and the Discrete Sine Transform to obtain the electric potential. This approach automatically enforces the zero-potential constraint on the rectangular boundary of the integration domain.
This contribution presents a detailed study of the phase-space structure and the characteristics of the trapping and transport process as a function of the beam intensity in a simplified model of the PS ring based on a FODO cell. We show that the space-charge forces cause an abrupt change in the halo formation during the trapping process when the intensity exceeds a threshold. Future prospects of this study are the application of our model to the realistic lattice of the PS with elliptic conducting boundary and the comparison with available experimental data.