Characteristics of the JAERI Circular Magnetic Multipole Line-Cusp Ion Source

Abstract

A circular magnetic multipole line-cusp ion source has been developed for use as a short-pulse neutral beam injector. This source has produced hydrogen ion beams of up to 30 A at 30 keV for 100 ms. The ion saturation current density was uniform within ⁵5% over the 18.5 cm diam. area of the extraction grid. The arc efficiency for a beam current of 30 A was 1.2 A/kW with an arc current and voltage of 260 A and 100 V, respectively, and the pressure in the source was 3.5 mTorr. The ion species ratio from the source was measured and proton ratios exceeding 70% were obtained at an ion current density of 0.23 A/cm².