Beam Dynamics for a High Current 3 MeV, 325 MHz Ladder-RFQ

After the successful measurements with a 0.8 m prototype (see Fig. 1), a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3 MeV according to the design parameters of the Proton Linac at FAIR. The development of an adequate beam dynamics design was done in close collaboration with the IAP resonator design team. A constant vane curvature radius and at the same time a flat voltage distribution along the RFQ was reached by implantation of the modulated vane geometry into CST Microwave Studio RF field simulations. Points of reference for the beam dynamics layout are the beam dynamics designs of C. Zhang* and A. Lombardi**. The Code RFQGen*** was used for the beam dynamics simulations. In order to increase the transmission and to reduce the longitudinal and transversal exit emittances, the evolution of the modulation parameter m within the first 90 cells was investigated in detail. This paper presents the simulation results of this study.