Michail Zampetakis | Searcharxiv

arXiv2023

Interplay of space charge and intrabeam scattering in the LHC ion injector chain

The ion injectors of the CERN accelerator chain, in particular the Super Proton Synchrotron (SPS) and the Low Energy Ion Ring (LEIR), operate in a strong space charge (SC) and intrabeam scattering (IBS) regime, which can degrade beam quality. Optimizing the ion beam performance therefore requires studying the interplay of these two effects in tracking simulations by incorporating both SC and IBS effects interleaved with lattice nonlinearities. In this respect, the kinetic theory approach of treating IBS effects has been deployed. A modified stochastic IBS kick is introduced, with friction and diffusion coefficients derived in two forms: an efficient Nagaitsev formulation based on complete elliptic integrals of the second kind, and a complete Bjorken-Mtingwa formulation. This IBS kick is implemented in PyORBIT and extensively benchmarked against analytical models. Results of combined space charge and intrabeam scattering simulations for the SPS and LEIR are presented and compared with observations from beam measurements.

physics.acc-ph↗

arXiv2023

Interplay of space charge, intrabeam scattering and synchrotron radiation in the Compact Linear Collider damping rings

Future ultra-low emittance rings for electron/positron colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intra-beam scattering (IBS) and space charge in the vicinity of excited betatron resonances is assessed. In this respect, two algorithms were developed to simulate IBS and synchrotron radiation effects and integrated in the PyORBIT tracking code, to be combined with its widely used space charge module. The impact of these effects on the achievable beam parameters of the Compact Linear Collider (CLIC) Damping Rings was studied, showing that synchrotron radiation damping mitigates the adverse effects of IBS and space charge induced resonance crossing. The studies include also a full dynamic simulation of the CLIC damping ring cycle starting from the injection beam parameters. It is demonstrated that a careful working point choice is necessary, in order to accommodate the transition from a non-linear lattice induced detuning to a space-charge dominated one and thereby avoid excessive losses and emittance growth generated in the vicinity of strong resonances.

physics.acc-ph↗