Characteristics of Pulsed Heavy Ion Beam Generated in Bipolar Pulse Accelerator

Abstract

SUMMARYWe have developed a new type of a pulsed ion beam accelerator named “bipolar pulse accelerator” for improvement of the purity of the intense pulsed ion beam. The system utilizes a magnetically insulated accelerate on gap and was operated with the bipolar pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside of the grounded anode. Source plasma (nitrogen) of current density of ≈30 A/cm2 and pulse duration of ≈1.0 μs was injected into the acceleration gap. When the bipolar pulse of −114 kV, 70 ns (first pulse) and 85 kV, 62 ns (second pulse) was applied to the drift tube, the ions were successfully accelerated from the grounded anode to the drift tube in the first gap by the negative pulse of the bipolar pulse. The pulsed ion beam with current density of 60 A/cm2 and pulse duration of ≈50 ns was obtained at 48 mm downstream from the anode surface. The energy spectrum of the ion beam was evaluated by a magnetic energy spectrometer. The ion energy was in reasonable good agreement with the acceleration voltage, that is, first pulse (negative pulse) voltage of the bipolar pulse.