LEBT Dynamics and RFQ Injection

The Low Energy Beam Transport (LEBT) section at the accelerator-driven neutron source FRANZ consists of four solenoids, two of which match the primary proton beam into the chopper. The remaining two solenoids are intended to prepare the beam for injection into the RFQ. In the first commissioning phase, the LEBT successfully transported a 14 keV He beam at low intensities. In the current commissioning phase, the beam energy is increased to the RFQ injection energy of 120 keV. In the upcoming step, the intensity will be increased from 2 mA to 50 mA. Beam dynamics calculations include effects of different source emittances, position and angle offsets and the effects of space charge compensation levels. In addition, the behavior of the undesired hydrogen fractions, H²⁺ and H³⁺, and their influence on the performance within the RFQ is simulated.