Cooling rates and intensity limitations for laser-cooled ions at relativistic energies

TL;DR

This paper investigates the feasibility and limitations of laser cooling for relativistic ion beams, analyzing excitation mechanisms, cooling forces, and effects of beam intensity, with simulations and case studies for specific ion accelerators.

Contribution

It provides a detailed analysis of laser cooling processes for relativistic ions, including scaling laws, optimized scenarios, and the impact of beam effects, supported by simulations and practical examples.

Findings

Cooling force scales with relativistic factor γ

Optimized cooling scenarios identified for specific ions

Beam effects like intrabeam scattering impact cooling efficiency

Abstract

The ability of laser cooling for relativistic ion beams is investigated. For this purpose, the excitation of relativistic ions with a continuous wave and a pulsed laser is analyzed, utilizing the optical Bloch equations. The laser cooling force is derived in detail and its scaling with the relativistic factor $\gamma$ is discussed. The cooling processes with a continuous wave and a pulsed laser system are investigated. Optimized cooling scenarios and times are obtained in order to determine the required properties of the laser and the ion beam for the planed experiments. The impact of beam intensity effects, like intrabeam scattering and space charge are analyzed. Predictions from simplified models are compared to particle-in-cell simulations and are found to be in good agreement. Finally two realistic example cases of Carbon ions in the ESR and relativistic Titanium ions in SIS100 are compared in order to discuss prospects for future laser cooling experiments.