High current ion injectors for long-pulse induction accelerators

This paper presents results of our recent study on reproducibility of ion beams extracted from. a grid-controlled vacuum arc ion source. Mass-spectroscopy measurements showed that the vacuum arc discharge plasma sometimes contains large amount of impurities. We found that these impurities change a space-charge-limited current value of the extraction gap and degrade the reproducibility of the extracted ion beams. We also found that the production of impurities can be suppressed with a liquid-N2 trap installed near the arc electrode.