TRANSPORT AND INJECTION OF HEAVY ION BEAMS WITH HIGH BRILLIANCE FOR THE GSI HIGH CURRENT INJECTOR

The GSI High Current Injector (HSI) is in routine operation for more than two years and has reached its designed performance for light and medium ion species. During commissioning a high intense 40 Ar 1+ -beam from a MUCIS ion source was used to optimize the transport through the high voltage gap, the mass spectrometer and the low energy beam transport (LEBT) up to the HSIRFQ. In the meantime an integrated solenoid lens between extraction system and post acceleration gap allowed for higher intensities, while the beam input parameters were changed. This implicated beam mismatch and losses in the LEBT and also in the RFQstructure due to an extended emittance. For the desired U 4+ -operation the design current of 15 emA is not yet available although the ion source can provide the desired current. This paper is focused on the transport from the ion source to the RFQ-injection of an U 4+ -beam under realistic space charge conditions, especially in the dc acceleration gap (up to 80 emA total Uranium current). In order to optimize a modified complex transport system to the RFQ, multi-particle beam dynamic calculations were carried out on the basis of measured emittances behind the gap. Proposed improvements providing a higher overall acceptance are reported. Additionally, investigations of a modified RFQ rod design resulting in a higher acceptance and lower emittance growth for the operation with high intense heavy ion beams will be presented.