Direct Injection of Intense Heavy Ion Beams from a High Field Ecr Ion Source into an Rfq

Beam intensities achievable from high performance ECR sources for highly charged ions are limited by the high space charge. For high performance ECR sources, the stray magnetic field of the source can provide focusing against the space charge blow-up of the beam when used with the Direct Plasma Injection Scheme (DPIS) developed for laser ion sources. A combined extraction/matching system has been designed for direct injection into a radio frequency quadrupole (RFQ) accelerator, allowing a total beam current of 12 mA for the production of highly charged U(0.49 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of the ion beam. The RFQ has been designed to suppress most of the charge states extracted from the ECR, acting as a filter for the desired U. This reduces the transport problem for the beam line as well as reduces the emittance for the transmitted charge states.