Generation of intense pulsed heavy ion beam by By type magnetically insulated ion diode with active ion source

Abstract

Intense pulsed heavy ion beam (PHIB) of ion current density more than several tens of A/cm2 can be applied to materials processes. To apply PHIB to materials processes purity of the beam is very important. For the purpose a new type of ion beam diode was developed. In the diode a new acceleration gap configuration is used with active ion source of pulsed plasma guns. Two types of plasma guns were developed to generate variety of ion beams, i. e. a gas puff plasma gun and a vacuum arc ion source. With the gas puff plasma gun, source plasma of nitrogen ions was produced. The current density of the plasma was evaluated to be ≈28 A/cm2 at 90 mm downstream from the top of the plasma gun. The plasma was injected into the acceleration gap of the diode and the ion diode was successfully operated at diode voltage ≈200 kV, diode current ≈2.0 kA, pulse duration ~150 ns. Ion beam of ion current density ~13 A/cm2 was obtained at 55 mm downstream from the anode. The energy and species of the beam was evaluated by a Thomson parabola spectrometer and found that N+ and N2+ beam of energy 60-300 keV were accelerated with impurity of protons of energy 60-150 keV. The purity of the beam was estimated to be 87 %. To generate metallic ions vacuum arc plasma gun was developed. The characteristics of the plasma gun were evaluated and source plasma of current density 8 A/cm2, plasma drift velocity 4.7 × 104 m/s was found to be obtained.