Abstract: A DC or high frequency ion source comprising a hollow cathode and a substantially hollow anode for applying a DC or alternating voltage; a gas inlet disposed at a first side of the cathode for supplying a discharge gas into the cathode; a cathode heater disposed between the anode and the cathode; a magnet disposed adjacent the anode to thereby improve the uniformity of a plasma; an ion extraction outlet disposed at a second side of the cathode opposite to the gas inlet and having an elongated rectangular shape; and an ion extraction electrode and an acceleration electrode for controlling the energy of extracted ions. Both the anode and cathode comprise substantially hollow boxes. The cathode includes an elongated rectangular cross section and is disposed inside the substantially hollow anode. The ion extraction electrode and the acceleration electrode have an elongated rectangular shape and an opening coextensive with the ion extraction outlet.