Simulation study on matching of laser ion source to RFQ linac with direct plasma injection scheme

An accelerator with low injection energy has been designed and constructed based on direct plasma injection scheme (DPIS); a pulsed C⁶⁺ beam with peak current of 11.28 mA, energy of 593 keV/u has been successfully achieved after accelerated with DPIS method. It is because that the beam produced by laser ion source is a pulsed one with large energy spread, high intensity and the design of a low energy transport line (LEBT) is also complicated, while the DPIS method is simple to achieve and improve the injection efficiency effectively; so, the laser ion source is directly connected to the RFQ without a LEBT in this equipment and then the laser produced plasma will be injected into RFQ with DPIS. In addition, the DPIS method is simulated by IGUN code and the parameters of extracted beam and its injection efficiency are obtained from simulation, which is well agreed with the measured one in our experiment. (authors)