A cold-cathode ion source with a closed-loop ion-emitting slit which is provided with means for generating a cyclically-variable, e.g., alternating or pulsating electric or magnetic field in an anode-cathode space. These means may be made in the form of an alternating-voltage generator which generates alternating voltage on one of the cathode parts that form the ion-emitting slit, whereas the other slit-forming part is grounded. The alternating voltage deviates the ion beam in the slit with the same frequency of the alternating voltage. In accordance with another embodiment, the aforementioned means may be an electromagnetic coil which generates a magnetic field which passes through the ion-emitting slit, thus acting on the condition of the spatial-charge formation and, hence, on concentration of ions in the ion beam. The cold-cathode ion source may be of any type, i.e., with the ion beam emitted in the direction perpendicular to the direction of drift of electrons in the ion-emitting slit or with the direction of emission of the beam which coincides with the direction of electron drift.