Focusing powerful beams of negative ions and neutrals

A scheme of obtaining powerful focused beams of neutral atoms after stripping negative ion beams is presented. A focusing diode with magnetic insulation was constructed after successful experiments in the generation of powerful beams of H⁻, C⁻, P⁻, and Pb⁻ in coaxial geometry. The cathode and anode are in the form of partial, concentric, spherical surfaces, i.e., the diode is intended for so-called ballistic focusing of beams on a target at the center of spherical surfaces. Magnetic insulation is provided by a coil placed on the high-voltage cathode. Cathode plasma was created in the diode by a new method, namely, by bombarding the cathode surface with positive ions. For this purpose, preliminary plasma was created behind the anode in which holes had been drilled. Experiments were performed on ERG accelerator at 600 – 800 kV (11 ohms, 200 ns) using a mylar detector and calorimeter.