Comparison of the simulation of electron beam transport in the double alpha magnet compressor of a 17-MeV electron accelerator using CST PS, TraceWin and RF-Track.✩

The ELSA facility is a 30 MeV electron accelerator with a double alpha magnet compressor positioned between two acceleration stages. Optimizing beam transport and determining the emittance limits of this device are key to the future development of the inverse Compton X-ray source developed on ELSA, making accurate simulations —along with a thorough understanding of their assumptions and limitations— essential. Three different codes, namely CST PS, TraceWin and RF-Track, each based on different principles, have been compared in the specific case of relativistic electron bunches with short curvature radii trajectories in the alpha magnet compressor. Since CST PS and RF-Track make calculations in the laboratory frame while TraceWin works in the bunch reference frame, a direct comparison could not be achieved directly. It was enabled through the development of a robust numerical method that derives phase space and emittance in the bunch frame from the positions and momenta of the particles in the laboratory frame (as exported from CST PS and RF-Track). This method is fully described in this paper.