The design and operation of a gas-discharge neutralizer of positive ion beams is presented. It is based on the discharge with crossed electric and magnetic fields initiated by the ion beam, which travels through the device, without an additional energy source. Depending on the pressure, there are two types of the discharge inside the neutralizer: high-voltage (at a low pressurep<3×10−4 Torr) and magnetron (at a high pressurep>3×10−4 Torr). In the high-voltage regime, the ion beam is partially neutralized. Full ion beam compensation is achieved in the magnetron regime. ©1997 American Institute of Physics.