Characteristics of cylindrical Hall ion source with floating potential magnetic pole discharge

Abstract

The discharge characteristics of a cylindrical Hall ion source (CHIS) with floating potential magnetic poles and grounded magnetic poles were investigated through experiments and simulations. The results revealed that the ion density distribution and ion energy were mainly affected by the discharge voltage and magnetic pole potential. The current utilization rate is 82%–93%, which is much more efficient than that of the conventional Hall ion source with grounded magnetic poles. As the gas supply increased, the floating potential of the magnetic pole increased. Under the same discharge current condition, the discharge voltage of a Hall ion source with floating magnetic poles is 300 V larger than that of grounded magnetic poles; meanwhile, this type of ion source has a higher mean ion energy and better uniformity of ion beam distribution. Ion acceleration in the CHIS with floating magnetic poles is expected to occur predominantly in the longitudinal direction and toward the CHIS outlet. The non-uniformity of the ion beam current density within a diameter of 40 mm along the radial directions approximately ±11.7% at a discharge voltage of 800 V, which is helpful for material surface cleaning, etching, sputtering, and ion beam-assisted deposition applications.