Abstract: An electron beam generator includes: an electron emitting cathode (1); an anode (3) with an anode bore (4) for the passage of an electron beam (6); a Wehnelt electrode (2) between the cathode (1) and the anode (3) for controlling the electron beam; the cathode (1); the anode (3) and the Wehnelt electrode (2) disposed within a vacuum chamber (100); and a magnetic unit (7) disposed between the cathode (1) and the anode (3) for generating a static transverse magnetic field causing the electrons to be deflected along a curved path until the electrons enter the anode (3) such that ions follow an ionic path back to strike the Wehnelt electrode (2) and are kept from striking the cathode (1) by displacement caused by the ionic path. The present invention reduces the number of ions that impact the cathode and reduces the number of ions that are formed by the ionization of residual molecules, increasing the service life of the cathode.