An extraction system design with a strongly inhomogeneous electric field for a JYFL electron cyclotron resonance ion source

A new ECR ion source extraction system has been designed. The design is based on the extraction conditions of the JYFL 14 GHz ECRIS, and its performance is compared to the existing extractor via numerical modeling. The aim is to improve the formation and quality of high-intensity ion beams. The plasma and the puller electrodes shape were changed. The plasma electrode has a narrow tip extruding toward the puller. It causes the electric field to increase near the plasma meniscus and subsequent higher ion velocity growth rate, which leads to the beam space charge reduction at fixed current and acceleration voltage. The extractor was developed with the ion optical code IBSimu. The initial beam parameters were taken from the experimental data. The calculations showed that the new extraction system allows to increase the total extracted current without compromising the beam quality. The new design allows the beam formation optimization for lower extraction voltages overcoming the present space charge limit.