High brightness point-like source for intense ion beam

By a pinched electron beam diode having electrodes in a conical shape, high brightness point-like ion beam source was obtained. The apex angle of the anode and the cathode are 56° and 40° respectively. The diameter of the cathode is 8 cm. The applied voltage is 200–250 kV and the diode current is 30–35 kA. The mean ion current density within 16 mm around the axis is about three times that from an usual flat parallel diode with the same dimension and impedance. The ion beam is emitted from a small region (∼6 mmφ) at the apex of the conical anode.