A closed loop exit hole is formed in a magnetically permeable end wall (2) of an enclosure (1) of a closed electron drift ion source. Parts of this end wall separated by the exit hole serve as pole pieces (7 and 8) of the magnetic system and define the first pole gap. The magnetic system includes pole pieces (9 and 10), which define the second pole gap made in the form of a closed loop exit hole and arranged along the direction of ion emission. Magnetomotive force sources (5 and 6) are located in space between two groups of magnetic terminals. The ratio of width of each pole gap and distance between pole pieces of the first (7 and 8) and second (9 and 10) magnetic gaps along the direction of ion emission is not less than 0.05.The invention allows the intensity of the generated ion beam and the energy of ions to be increased, and this is provided by the homogeneous distribution of ion current density across the ion beam section.