Abstract: An electron source having a cathode and a permanent magnet perforated by a plurality of channels extending between opposite poles thereof. The magnet generates, in each channel, a magnetic field which forms electrons received from the cathode into an electron beam for guidance towards a target. An electrode grid is disposed between the cathode and the magnet for controlling flow of electrons from the cathode into each channel. A magnetic field null region of each magnetic field is positioned at a location remote from the electrode grid. Because the null region is positioned remotely from the grid electrodes, flow of electrons can be improved without increasing electrode drive voltage.