Development of Bipolar Pulse Accelerator for Intense Pulsed Heavy Ion Beam

A new type of a pulsed ion beam accelerator named “bipolar pulse accelerator (BPA) ”has been proposed to improve the purity of the intense pulsed ion beam. In order to confirm the principle of the BPA, we have developed a bipolar pulse generator and a prototype of the accelerator. When the bipolar pulse generator was operated at 70 % of the full charge condition, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The BPA system utilizes By type magnetically insulated acceleration gap and is operated with the bipolar pulse. When the bipolar pulse with voltage of about ± 100 kV and pulse duration of about 70 ns was applied to the drift tube, the ions were successfully accelerated from the grounded anode to the drift tube in the 1st gap by the negative pulse of the bipolar pulse and the pulsed ion beam with current density of 40 A/cm and pulse duration of 30 ns was obtained at 50 mm downstream from the anode surface. In addition, part of the ion beam was again accelerated toward the grounded cathode in the 2nd gap by the positive pulse of the bipolar pulse. The pulsed ion beam with the peak ion current density of 2.1 A/cm and the beam pulse duration of 30 ns was obtained at 30 mm downstream from the cathode surface.