Arc discharge performance analysis for a high power bucket ion source

To match the large power long pulse neutral beam injectors for HL-2A Tokamak, a circular magnetic multipole line-cusp ion source (namely a bucket ion source) has been designed. The arc chamber of this ion source is a water-cooled, stainless-steel cylinder 26 cm in diameter, 4 mm thick, and 24 cm long. So far, many arc discharge experiments on this ion source have demonstrated that the plasma density has been 0.24 A/cm², for 3 seconds duration, within 5%-7% plasma uniformity, and 3 seconds maximum pulse. Arc discharge characteristics, such as the gas pressure dependence and filaments arrangements dependence have been studied experimentally and theoretically in this paper. (authors)